Download 8.8.2 Routine Tests

SECTION - I
REPLACEMENT OF TURBINE MAIN INLET VALVE AND SLUICE
VALVES
1.1
Scope: This section of the specification cover the following scope of works: i) Dismantling/removing of existing four (4) No.’s Butterfly type Turbine Main
Inlet Valves (MIV), and four (4) No.’s sluice gates, all services, labour, tools
and tackles required for dismantling including carriage, stacking at Owner’s
store/ yard.
ii) Design, engineering, manufacture, shop assembly & testing before dispatch,
packing and forwarding, transportation, insurance, handling, delivery, storage
at site, erection, testing & commissioning of four (4) Nos. Butterfly type
Turbine Main Inlet Valves and four (4) No.’s sluice valves, as detailed in this
specification and handing over to HPSEB LTD. complete with accessories,
equipment, devices, piping, instruments, cabling and wiring etc. including all
services, labour, tools and tackles.
1.2
Standards: The turbine main inlet valve to be supplied shall conform to the provision
contained in the latest edition of IS – 7326 (Part 1, 2 & 3):1992 and other
relevant IEC and IS standards in all respect.
1. 3
Basic Parameters: The following basic parameters and other pertinent data shall apply to the
turbine inlet valve systems:
1.4
Type of valve
Butterfly
Valve diameter
Elevation of valve centreline
500 mm (shall have to be matched with
the spiral casing of turbine).
3600.399 m.
Design discharge
0.856 cumecs
Net head
79 m
Max. pressure
12 Kg/cm2
Penstock diameter
700 mm (internal)
Valve Design and Construction Requirements
The main inlet valve shall be of the disc and trunnion, single seating butterfly
valve to operate with complete reliability and good hydraulic properties,
furnished with upstream and downstream pipes of suitable length. The inside
diameter of the valve shall not be less than the internal diameter of spiral
case. The valve together with its bypass valve assembly, drain valve, air
valves and operating equipment shall be designed to fit into the existing
space available with proper regard to accessibility. The valve shall be
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supported on the concrete pedestal and secured by anchor bolts. The valve
body and operating mechanism shall be designed for installation and removal
from above by means of the powerhouse crane. The valve shall open through
oil operated hydraulic servomotor by means of a high-pressure oil system and
shall be capable of closing through counterweight under most adverse
conditions.
The oil servomotor shall be so designed that when the valve opens, the
counterweight should lift up and on reaching at the end position of travel, a
proximity switch shall trigger giving a signal to trigger the motor. The oil thus
trapped in the cylinder keeps the piston extended and the valve remains open
with counterweight raised.
The cylinder piston seal shall be dynamic type and may cause some leakage,
which may cause the counterweight to creep down over a period of time. This
will un-trigger proximity switch and start the pump to push back the
counterweight and keep the valve fully open.
The normal closure and emergency closure shall be initiated by operation of
the solenoid poppet valve. The pressure created by the counterweight acting
on all the trapped oil shall be transferred to the pilot operated check valve,
which opens and lets out the trapped oil back to the tank. The valve shall
close down due to the action of the counterweight. Means shall be provided to
control the valve closing speed by controlling the flow of oil back to the tank
via pressure and temperature compensated flow control valve.
1.5
Operating Conditions
1.5.1
Design
The operating mechanism shall be of sufficient capacity to close the valve in
not more than 60 seconds against the discharge and head conditions
indicated below. The opening time shall be approximately equal to the closing
time. The closing and opening time shall be adjustable between 45 and 120
seconds with positive means for locking these adjustments. The minimum
permissible closing time shall be controlled by a fixed orifice installed directly
at the servomotor outlet as to prevent fast closure of the valve in case of oil
piping failure. The valve should be capable of closing under most adverse
conditions at maximum flow.
The design pressure shall be 12 kg/cm2
1.5.2
Normal operation
The butterfly valve and its operating mechanism, extension pipes, coupling,
and related bypass system, sealing and drain system shall withstand safely
the maximum stresses from the following operating conditions, with stresses
in the materials not exceeding the maximum allowable stress for normal
operation specified in clause- 4.3 of Vol.- 2A.
1.
Continuous operation with valve in the open position passing the rated
discharge of the turbine of 0.856 cumecs under the rated operating
net head on the turbine of 79 m and a discharge of 0.96 cumecs while
running at 10% overload.
2
1.5.3
2.
With valve in open position withstanding total maximum water
pressure 12 kg/cm2 on the valve centreline, which includes the design
pressure rise allowance.
3.
With valve in closed position withstanding a maximum water pressure
12 kg/cm2.
Emergency closing
The valve and its operating mechanism, extensions, by-pass system, seal,
drain and air release valves and couplings shall withstand the maximum
stresses from closing under a flow corresponding to the discharge of the
turbine of .856 cumecs.
1.6
Valve Body
1.6.1
General
The valve body shall be in two pieces, made of welded plate steel, or of cast
steel, or a combination of both, bolted together by hydraulically or thermally
pre-stressed bolts. It shall be of rigid construction and adequately ribbed as
necessary to minimize distortion under full load and maximum pressure and
designed to transmit the hydraulic thrust to the upstream valve body
extension and penstock. The trunnion bearing housings and the flanges for
the bypass line shall be integral with the valve body and supported by it. The
valve body shall be provided with flanges for bolted connections to similar
flanges on the valve body extensions. The valve body shall be machined only
after it has been subjected to a stress-relieving heat treatment.
1.6.2
Foundation
Foundation details shall match the existing valve foundations. This is a
replacement job as such new foundation shall not be casted. Contractor shall
collect the necessary details from the power house site. It shall be the
responsibility of contractor for accuracy of foundation detail measurements.
1.6.3
Permissible Leakage
Maximum permissible leakage from the main valve should not exceed
2litre/min/metre periphery of seal when valve is new.
1.7
Flanged Extensions and Erection Joints
1.7.1
General
The butterfly valve shall be furnished with two valve body extensions, one for
the inlet side of the valve and another for the outlet side. A sleeve type
coupling (not transmitting any axial loads) shall be provided for connecting the
outlet extension pipe to the turbine spiral case. The extensions shall be of
plate steel construction, designed for a hydraulic pressure of 12 kg/cm2. All
necessary nuts, bolts and gaskets for the flanged connection between the
valve body and the extensions shall be furnished by the contractor. No
special supports will be provided for the extensions. Their weight, including
contained water shall be carried through the flanged joints to the valve body.
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1.7.2
Upstream Connection
The valve body inlet extension pipe which shall be of conical shape shall be
provided with bolting flanges at one end for connection to the valve body.
Bolts, nuts, and gasket for connecting the inlet extension to the valve body
shall be included in the supply. The connections of the extension pipe to the
existing penstock shall be of welded type. The contractor shall cut, chamfer
and weld together the end of the penstock and the valve extension pipe
including all necessary NDT or heat treatment.
1.7.3
Tolerance on Dimensions
The extension pipes shall be sufficiently true to round so that the difference
between maximum and minimum diameters, with temporary bracing in place,
measured inside or outside, at any cross section along the length shall not
exceed one per cent of nominal diameter for that section. The ends shall be
within a tolerance of plus or minus 1.0 mm of the plane normal to the axis of
the extension. The length of complete extensions shall conform to the limiting
dimensions. The tolerances listed are exclusive of any allowance for
shrinkage or distortion.
1.7.4
Bypass Connection
Pipe connections shall be provided in the inlet and outlet extensions for the
by-pass valve, and for a duplex pressure gauge and differential pressure
switch.
1.7.5
Downstream Connection
An extension pipe with a sleeve type coupling of an approved type shall be
furnished to connect the valve to the spiral inlet pipe. The coupling shall allow
the valve to be displaced along the penstock axis due to hydraulic forces and
thermal expansion/contraction to facilitate erection and dismantling of the
extension pipe to allow for any small differences in distributor extension
length. The extension pipe shall be complete with all necessary steel flanges,
seals or gaskets and coupling bolts.
The surfaces of the coupling in contact with the seal and the seal groove shall
be fitted with stainless steel plate.
1.8
Valve Disc and Trunnion
1.8.1
Valve Disc
The valve disc shall be made of cast steel or of welded plate steel or a
combination of both, ruggedly designed and heavily ribbed internally to
sustain full differential pressure across the closed valve disc with minimum
deflection. The disc shall be of the open-frame through flow type and shall be
shaped and finished to minimize flow disturbances. The disc shall be
accurately machined at its rim and provided with corrosion-resisting metal on
its periphery to protect it against corrosion and abrasion.
1.8.2
Valve Trunnion
The valve trunnion shall be of forged steel and shall extend into the valve disc
and shall be securely and rigidly attached to it. The outside ends of the
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trunnion shall be carried by the bearings in the valve body. The trunnion and
seal areas shall be provided with renewable, stainless steel sleeves or
suitable corrosion resistant coatings. Seal shall be provided at the outside
ends of the trunnion to minimize leakage. The trunnion seals shall be
designed and constructed for dependability, long life, and convenient
replacement.
1.8.3
Disc and Trunnion Seals
The valve disc and valve body shall be designed and machined to
accommodate the valve seal. The seals shall be of a design and constructed
of materials that will provide the maximum tightness consistent with
dependability, long life, minimum maintenance, and convenient adjustment
and replacement. The disc and trunnion sealing elements shall be of natural
rubber, or other suitable elastomer, sealing against corrosion resistant metal.
The seal retainers and fastening devices shall be made of suitable corrosion
resistant metal. The seal shall be adjustable, removable, and replaceable.
The adjusting may be accomplished either in the seal retaining element or the
seal seating element.
1.9
Main Bearings
1.9.1
General
The main bearings shall be of the sleeve type, supported integrally within the
valve body. The bearings shall be designed and constructed so that all
necessary adjustments may be made from outside the bearing housings. The
sleeve bearings shall be of corrosion resisting material and shall be designed
so that deflection and trunnion slope caused by the water load on the disc in
the closed position will not result in binding between the trunnion and sleeves.
The bearing shall be built into the valve body and shall transmit the loads to
body.
1.9.2
Bearing Type
The contractor shall determine from his own experience the most suitable
bearing design. The contractor shall submit his design to the Engineer-incharge for approval.
1.9.3
Lubrication
The disc trunnion bearing and all other points on the valve or operating
mechanism requiring lubrication shall be provided with self lubricating
bearing.
1.10
Bypass Valve and Piping
1.10.1
General
A by-pass line of not less than 50 mm nominal pipe size shall be provided and
shall be complete with hydraulically operated valve and necessary electrical
controls, hand gear operated guard valve on upstream side of by-pass valve and
piping, designed for a pressure of 12 kg/cm2. The opening and closing of the
valve shall be controlled by hydraulic pressure from the pumping unit.
5
The needle type by-pass valves shall be of cast or forged steel with wearing
parts of corrosion resisting material.
"Open", "intermediate", "close", Proximity limit switches, each with two
electrically independent contacts, shall be provided as required to accomplish
the specified control and alarm functions. The by- pass line will be used for
filling the turbine spiral casing and equalizing the pressure on the inlet valve
disc before opening the valve.
1.10.2
Pressure Gauge
A duplex pressure gauge and differential pressure switch for showing the
difference between the water pressure upstream and downstream of the
valve disc shall be provided. The pressure switch shall be provided with
potential free contacts to accomplish the specified control and alarm
functions.
1.10.3
Piping
The by-pass piping shall be of seamless steel pipe with steel flanged
connections, the necessary bolts nuts and gaskets shall be furnished by the
contractor.
1.11
Valves
1.11.1
Air Valve
One automatic spring loaded float type air valve complete with necessary
bolts and gaskets shall be furnished for installation on top of the downstream
extension pipe. The size of the valve shall be as required to exhaust the air
trapped in the spiral case when the butterfly valve by-pass is opened for filling
the spiral case and to admit air when the butterfly valve is closed and the
spiral case in being drained. The air valve shall be designed to prevent any
water spray during its operation.
1.11.2
Penstock and spiral case Drain Valves
One No. drain valves of suitable size, made of cast or forged steel, shall be
provided at the upstream and downstream connections of butterfly valve for
emptying the penstock and spiral casing. Drain valves shall be complete with
piping and fitting.
1.11.3
Sluice Valves :Four (4) No.’s manually operated sluice valves operated by geared
mechanism shall be provided with main inlet valve package, so that the
maintenance on MIV, if any, required could be carried out easily. The gate
shall be suitable for operating under hydraulic parameters specified for main
inlet valves. The test pressures shall be same as indicated for main inlet
valve. Sluice valves shall have identical foundations and other details as
those of existing ones. Bidder shall collect the necessary details from the
power house site before bidding.
1.12
Set of Sundry Items: Comprising of foundation bolts, sole plate, lifting brackets etc.
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1.13
Counter Weight
The counter weight shall be sized to provide net closing torque on the valve
disc under most adverse operating conditions and shall be of fabricated steel.
1.14
Operating Mechanism
The operating mechanism shall include suitable stops to limit the disc travel at
the fully opened and fully closed positions, and a manually operated locking
mechanism for holding the disc in the closed position. The lock shall be
capable of withstanding the full operating force of the operating mechanism.
Parts with sliding contact shall be self-lubricating bushings and corrosion
resistant shafts with surface finish and coating as required by the bushing
manufacturer.
A mechanical position-indicating device shall be provided on the operating
mechanism to indicate the position of the valve disc.
1.15
Control Devices
The operating mechanism shall be provided with at least the following control
facilities to accomplish the specified alarm, indication and interlocking
functions.

Oil pressure switch for sensing the operating mechanism oil pressure.

Water pressure switch for sensing the operating mechanism water
pressure.

Proximity switches showing open-closed and intermediate butterfly
valve position s and open/close positions of the by pass valve.
All the switches required shall be provided with at least two potential free
contacts.
1.16
Control System: The Inlet valve control system shall include all the sensory and operating
devices necessary to fulfil the functional requirement of the specification and
is to be provided by the bidder.
1.17
Oil and Water Piping: Oil piping shall be seamless, stainless steel pipes and shall include all piping
to the oil pressure supply system consisting of sump tank, pressure tank,
servomotor, actuator cabinet instrumentation etc. as required. The piping
shall be of such size that the maximum oil velocity shall not exceed 3.0 m/sec
in the pressure lines and 1.5 m/sec in the return lines. Minimum pressure
anywhere in the oil piping system during maximum speed of valve operation
shall not be less than 0.5 bars absolute. All oil piping shall be thoroughly
cleaned, oiled inside, and protected for shipment with flange protectors on all
flanges, screwed caps on threaded end and suitable plugs in plain ends.
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Water piping shall be made of heavy seamless stainless steel pipe and shall
be flanged.
1.18
1.18.1
Spares
Mandatory Spares : The below listed spare parts which comprise the total required for all turbine
inlet valves under this contract shall be supplied. The prices for the following
mandatory spare parts shall be stated separately in the offer. A set is defined
as the total number required for one butterfly valve.
1
2.
3.
4.
5.
6.
7.
8.
9.
1.18.2
Proximity Limit Switches of each type used
Pressure gauge of each type used
Rubber cords, o-rings sealing,
packing, gaskets etc.
Servomotor complete
Solenoid valve of each type used
Valve of each type used
Piston rings for
a)
Servomotor
b)
By pass valve
Bushes for main trunnion
Seal rings for by-pass valve
1 Set.
1 Set
2 Sets.
1 Set.
1 Set.
1 Set.
2 Sets.
1Set
2 Sets.
2 Sets.
Recommended Spares : An itemized list of additional spare parts, including prices, which the
contractor recommends shall be included in the Bid. In preparing this list, the
contractor shall give due consideration to the time delay involved if it were
necessary to obtain spare parts due to failure of a critical valve component.
The purchase of any or all of the additional spare parts recommended shall
be at the discretion of the Owner.
1.19
Maintenance Equipment The following tools and miscellaneous erection and maintenance equipment
and devices shall be furnished which shall be included in the price for the
main inlet valves.
 One complete set of case hardened wrenches for all sizes of nuts and
bolts used in inlet valve, suitably mounted and identified.
 One or more lifting lugs or hanger pins and slings for attaching the
assembled valve to the powerhouse crane.
 Any special tools and equipment or devices that may be required or
which may be useful for the most expeditious assembling or
dismantling of any part of the valves.
A complete list of special tools and equipment to be supplied with the butterfly
valves shall be submitted.
1.20
Shop Assembly and Tests -
1.20.1
Shop Assembly of valve: 8
The butterfly valve with extensions, by-pass valve and piping, operating
mechanism controls, locks and indicators shall be completely assembled in
the contractor's shop to assure satisfactory fit, and the assembly shall be
match-marked and doweled, where required, to assure correct re-assembly
and alignment in the field.
1.20.2.1
Shop Tests: -
1.20.2.2
General The completely assembled butterfly valve and by-pass valve with operating
mechanism and control mechanism shall be given an operating test, pressure
test and leakage test.
1.20.2.3
Operating Test: The completely assembled valve shall be operated through several opening
and closing cycles to demonstrate satisfactory operation.
1.20.2.4
Pressure Tests: With both ends of the valve extensions closed by means of test heads and
with the rotor disc in slightly open position, the valve body and by-pass
system shall be subjected to a hydrostatic test pressure of 18 kg/cm2 to
determine the soundness of the valve body and whether or not there are any
leaks. The pressure in the valve body shall be maintained for at least 30
minutes. Upon completion of the leakage test specified below, the pressure
on the upstream side of the valve disc (in closed position) shall be kept at
hydrostatic test pressure of 18 kg/cm2 for not less than 30 minutes with zero
pressure on the downstream side and the downstream cover removed, to
determine the soundness of the valve disc.
1.20.2.5
Leakage Tests: Leakage tests shall be performed on the valve seal under a hydrostatic
pressure of 12 kg/cm2 for not less 30 minutes. The leakage at this pressure
shall be measured.
1.20.2.6
Witnessing of Shop Assembly and Tests: The shop assembly and tests shall be witnessed by the Engineer-in-charge or
his representative as per the requirements of approved inspection and quality
assurance document.
1.21
Installation: The contractor shall assemble (if required), erect, place and level the valve
body servomotor and control system on the existing foundation. The
contractor shall install interconnecting piping between equipment including
support and hangers. All rust preventive compounds shall be removed, and
any rust that may have formed on the parts shall be carefully removed. The
oil piping shall be thoroughly cleaned and flushed before the oil is placed in
the system. Extensions shall be fitted and welded. Flanged extensions and
erection joint, and all welds shall be radio graphically examined. The bidder
has to do all the works related to erection, testing and commissioning of
butterfly valves complete in all respects. Supply of all types of consumables
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1.22
and other materials required for erection including welding electrodes etc.
shall be in the scope of the bidder.
Field Testing: The contractor shall furnish a complete outline of the proposed methods and
procedures to be followed for the main inlet valve field assembly, erection,
testing, including a list of equipment and instruments to be used, to the
Owner's Representative for review at least 60 days before the scheduled, first
valve testing.
All testing equipment and instruments shall be furnished by the contractor and
will remain the Contractor's property after the fulfilment of all field tests.
The contractor shall furnish a complete report of the field tests of the
equipment.
The tests at site should at least include the following:

Pressure test of all field installed piping for oil and air at 1.5 times the
maximum working pressure.

Leakage test of all field piping with pressurized air and soap solution.

Opening and closing of by-pass valve

Opening and closing of main Inlet valve under balanced pressure
conditions.

Closing of main Inlet valve at rated flow

Operation of all controls including the mechanical locking device.

Other test as deemed necessary by the Engineer-in-charge
The bidder shall provide all necessary material and labour for performing all
the above tests.
1.23
Civil Engineering Works :Civil Engineering works related to addition and alteration of foundations of
Main Inlet Valve shall be in the scope of contractor. Contractor shall quote the
prices inclusive of civil works. Contractor shall be liable for correct
assessment of civil works before bidding. No deviation of civil works shall be
allowed after price bid is opened.
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SECTION - II
REPLACEMENT OF TURBINE RUNNERS
2.1
Scope: This section of the specification cover the following scope of works: i) Dismantling/removing of existing four (4) No.’s runners of Francis type
Turbine, all services, labour, tools and tackles required for dismantling
including carriage, stacking at Owner’s store/ yard.
ii) Design, engineering, manufacture, shop assembly & testing before dispatch,
packing and forwarding, transportation, insurance, handling, delivery, storage
at site, erection, testing & commissioning of four (4) Nos. runners of Francis
type Turbine as detailed in this specification and handing over to HPSEB
LTD. complete with runner templates. including all services, labour, tools and
tackles.
2.2
Technical requirements: The runner shall be made of cast stainless steel having a material
composition of 13% chromium and 4% nickel. The contractor shall assure that
a higher degree of quality finish and control is maintained during the
manufacture of the runner, including bar test specimens, non-destructive flow
detecting inspection, stress relieving of the casting and balancing. All
surfaces of the runner shall be finished smooth without any humps or hollows,
depressions, cracks and projections.
The contours of the runner blades shall be accurate and shall be finished, so
that the blade profile precisely conforms to the model design within the
tolerance set out in IEC Publication-193. The blades shall be evenly and
symmetrically spaced. Before shipment/despatch, manufacturer shall check
the hydraulic surfaces with templates and submit proof that the finished
runner contours and shape meet with the tested model and the design
requirement. Templates for guidance in restoring blade shapes to original
contour shall be supplied with runners.
The runner shall be designed to safely withstand the stresses due to
operation at runaway speed under condition of maximum head with no load
on generator and any position of the wicket gates. Special attention shall be
paid to reduce stress concentration at the fillet of the blade outlet edge with
the band and crown.
Replaceable stainless steel labyrinth seal shall be fixed to the runner on both
ends with the help of stainless steel fasteners to reduce the leakage.
The runner shall be statically and dynamically balanced at the works and shall
be designed and constructed to withstand safely the stresses developed due
to operation at runaway speed under conditions of maximum head including
pressure rise due to water hammer.
The runner shall be attached to the generator/turbine shaft through bolts with
nuts and locking devices. The coupling bolt holes in the runner shall be line
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reamed with the runner and shaft assembled. The connection shall be
designed for tightening and holding from the above as required for
incremental assembly. The equipment required for the assembly and
disassembly of the runner shall be included in the offer.
Runner inspection and quality control shall be according to CCH-70-2.
Acceptance criteria shall be in accordance with these specifications and shall
be subject to approval by owner's representative.
2.3
Performance Requirements: Bidder shall quote with the understanding that supply of runner is a part of the
complete renovation job including the overhauling of turbine. Bidder may have
to do reverse engineering wherever required. Accordingly efficiencies are to
be quoted for complete turbine including runner.
Guarantees for Unit Output, Efficiency & Penalties for Shortfall
The bidders shall offer runners having the specified rating and highest
feasible efficiencies in the permissible range of operation. The bidder on the
bidding stage shall supply supporting documents for the prescribed
guarantees by means of displaying results from earlier model tests of the
runner which conforms as much as possible to the one now being offered.
The output and efficiencies shall be guaranteed under penalty as given
below.
The turbine Output & Efficiency shall be guaranteed by the bidder in
respect of the following:

Rated output of 530 kW at rated net head of 79 m.

Over load output of 583 kW at rated net head of 79 m.

Output at minimum net head of 79 m shall not be less than 530 kW.

Turbine efficiencies at 110%, 100% & 60%.
Weighted Average Efficiency
The guaranteed weighted average efficiency at the rated net head shall
be calculated as follows:
av. = 0.30 110 + 0.40100 + 0.3060
Where
av.
= Weighted average efficiency
110
= Efficiency at 110% of rated output when operating at net head
of 79 m
100
= Efficiency at 100% of rated output when operating at net head
of 79 m
60
= Efficiency at 60% of rated output when operating at net head
of 79 m
12
Penalties will be evaluated and imposed as per clause 2.4 in case of short
fall in the test values of the rated unit output and weighted average
efficiency vis-à-vis the guaranteed values. Weighted average efficiency
and rated output of the unit will be verified after installation and
commissioning of the generating units on the basis of field acceptance
tests on any unit to be decided by the owner. For equalisation in the
comparison of bids, the weighted average efficiency as defined in clause
2.3 will be used.” Bidders shall quote turbine efficiencies in excess of
94%. Bids with output efficiencies less than 94 % shall be rejected
2.4
Penalties and Rejection Limit for Shortfall in overall Output and overall
Weighted Average Efficiency of unit :
Field acceptance test as per IEC code shall be carried out to
determine the actual output and the efficiencies of the unit at various points of
operation of the unit.
Penalties to be levied for any shortfall in the tested values of rated unit
output and of the weighted overall average efficiency of unit vis-à-vis the
guaranteed values respectively shall be computed as follows:
a)
Output
For each one 10th of one
percent (0.1%) shortfall in test value
of rated output vis-à-vis guaranteed MW.
b)
Rs. 8000
(Rs. eight thousand
for each unit)
Weighted overall Average Efficiency
For each one 10th of one percent
(0.1%) shortfall in test Value of
weighted average efficiency vis-à-vis
guaranteed value.
Rs. 8,000
(Rs. Eight thousand
for each unit.)
For fractional values of the shortfall in percentage, the penalty
amounts will be computed on pro-rata basis.
The penalties on account of shortfalls of output and the weighted
average efficiency shall be computed separately. The contractor will have
option to conduct output and efficiency test on all the units at his own cost to
prove that such contractual guaranteed values are fulfilled. Only units not
fulfilling the guarantees will be subjected to penalty by multiplying the
penalties for one unit by the no. of units and the total amount of penalty shall
be sum of these two. The penalties shall be applicable if shortfall in either the
rated output or the weighted average efficiency is less than the corresponding
guaranteed figures in the range of 0 to 1.99%.
If the tested values of either the rated output or the weighted average
efficiency are less than the corresponding guaranteed figures by two (2%)
percent or more after allowing the tolerances for efficiency as per IEC, the
owner shall have the right to reject the equipment. No tolerance limits shall be
permissible over the field tested figures of rated output.
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SECTION-III
REPLACEMENT OF GOVERNING SYSTEM AND TURBINE CONTROL PANEL
3.2.1
Scope
This section of the specification cover the following scope of works: i) Dismantling/removing of existing four (4) No.’s mechanical governors, Turbine
Auxiliary Control Panels, associated sensing/feedback instruments, all
services, labour, tools and tackles required for dismantling including carriage,
stacking at Owner’s store/ yard.
ii) Design, engineering, manufacture, shop assembly & testing before dispatch,
packing and forwarding, transportation, insurance, handling, delivery, storage
at site, erection, testing & commissioning of four (4) Nos. Digital governors,
Turbine Auxiliary Control Panels, associated sensing/feedback instruments as
detailed in this specification and handing over to HPSEB LTD. complete with
accessories, equipment, devices, piping, instruments, cabling and wiring etc.
including all services, labour, tools and tackles.
3.2.2
General
Governor for each unit shall be supplied and shall be of the digital
programmable electronic type. Governor module shall be mounted in Turbine
Auxiliary Control Panel. All equipment shall be suitable for continuous duty
and interchangeable between the units. All control functions of generating unit
shall be implemented from the Turbine Auxiliary Control Panel. A touch
screen in addition to control switches and push buttons shall be provided on
each TACP for unit control. Any equipment/hardware not mentioned, but
required for unit control shall also be provided.
Each governor shall be complete with speed sensing elements, restoring
mechanism, pressure system, oil piping, shut down and speed-no-load
solenoids, oil pressure level failure relays, gate position switches, speed
switches, automatic brake valve and all parts & accessories required to
constitute a completely automatic assembly for regulating the speed and
controlling the gates of the turbine with which it is to be used.
It is in the scope of these specifications that the governor shall be
complete with all necessary devices for completely automatic and remote
control, synchronising, and supervisory load frequency control and shut down.
Remote control shall be from the control room of the power house.
The normal pressure for operation of the pumps, pressure tank and
servomotors of the turbine shall be 40 to 90 kg/cm2 .The speed sensing
element shall be capable of causing the actuator relay valve to pass oil in the
direction to effect corrective movement of the turbine wicket gate in
consequence of a speed variation of less than 1/100th of 1 percent.
All actuators and control assemblies shall be enclosed in a metal cabinet of
rigid construction and neat appearance, which shall be dust proof and
properly ventilated. All gauges, indicating and control devices shall be
mounted on the front panels of the actuator cabinet in a symmetrical and
convenient manner and shall present a pleasing appearance in size shape
14
and arrangement. Inspection doors shall be provided on all exposed sides
and on the top for access to the actuator equipment and these doors shall be
fitted with locking arrangement, handles and latches. Instruments within the
cabinet shall be readily accessible for adjustment and maintenance through
the inspection doors.
Layout of governor actuator cabinet and pump set equipment shall meet the
approval of Engineer-in-charge.
3.2.3
Capacity of Governor:
The rating of the governor shall not be less than the capacity of the
servomotors for operation of the turbine wicket gates. The governor shall be
capable of supplying sufficient oil to the servomotors to operate the turbine
gates to give an effective time from a complete closing or opening stroke for
the range of operating times with a minimum oil pressure under the maximum
net head on the turbine. The oil velocity in the pipes shall not exceed 3m/sec.
The governor oil pressure system shall be designed for the extreme case of
closing, opening and final closing of the wicket gates with both oil pumps and
compressed air admission valve inoperative.
3.2.4
Governor Operating Parameters.
The speed governing of the generating unit shall be carried out by a
combination of proportional, integral and differential actions and non-linear
characteristics in order to provide best quality of control. The governor shall
have high sensitivity, quick response to speed/load changes, least possible
dead band time and wide adjusting ranges as given below in respect to
various parameters:
a)
Sensitivity speed
Not more than 0.01% of
rated.
b)
Speed level settings.
Adjustable between (-) 3 Hz
& (+) 3Hz of normal 50 Hz
(85% to 110%).
c)
Permanent speed droop
Adjustable between 0-10%.
d)
Temporary speed droop.
Adjustable between 0-100%.
e)
Speed dead band at rated
speed.
less than 0.02%.
f)
Governor dead band times
0.2 sec. for step load change
of 10% of rated load or more.
g)
Wicket gate closing time
Adjustable 4 to 20 sec. having
dual fast and slow action.
h)
Wicket gate opening time
Adjustable, 20 to 60 sec.
The turbine wicket gate closing time shall be specified. For the closing
operation a dual rate of closure has been considered to be required to restrict
transient speed rise of the turbine to within reasonable limit. The governors
shall therefore provide a dual rate of closure for the wicket gates, faster in the
15
first half of the closing period and slower in the second half. The governor
closing and opening time has the dual rates of closure & shall be adjustable
within the specified range.
3.2.5
Provisions in Governors.
1. The digital governor shall have provisions for setting/adjusting and
indication display of the set values of various governor
characteristics/parameters with the help of the keyboard viz.
a) Permanent speed droop.
b) Temporary speed droop.
c) Temporary speed droop decay time constant.
d) Sensitivity.
e) Frequency dead band
f) Speed regulation.
g) Power regulation.
h) Opening limitation.
i) Speed set point.
j) Output set point.
k)
Monitoring and supervision of speed, power and position feed back
signals.
l) Other essential devices for smooth operation, protection and safety of the
units.
2. It shall also have other essential provisions and devices as protective
devices for locking out on failure of the regulator, for transfer to emergency
manual control on UCB.
3. The hydraulic actuator units shall have various devices, control indications
as given below: a) Two nos. remotely controlled from control room shut down devices for
normal and emergency closure of wicket gates. For emergency closure,
two solenoid-operated valves shall be fed from two independent 110V dc
sources.
b) Independent emergency solenoid valve which operates in emergencies
and catastrophic condition and send the pressurised oil directly to the
wicket gate servomotors bypassing the governor.
c) Manual control devices acting directly on the actuator hydraulic system
allowing opening and closing of wicket gates to any position. The actuator
of valve shall have provision for manual operation also.
16
d) Wicket gate maximum opening limiting device remotely operatable.
e) Wicket gate position and gate limit transmitters for remote indication.
f) Direct indication of gate limit and position on actuator units.
g) Other essential devices not specified but required for smooth operation,
protection and safety of the units.
4) Rong Tong Power station is located in remote area and nearest grid
(22 Kv) is available at 220 Km away. Most of the time power station
shall run in isolated mode (Speed control mode). Governor shall be
capable of operating under such conditions in isolated mode.
Necessary hard ware and software provisions to this effect shall be
made in governor.
3.2.6.
Speed Sensing/Speed Switches.
Speed of the unit for governor operation shall be measured by inductive
transducer actuated by toothed wheel located on the generator unit shaft.
Two fully independent speed sensing systems shall be installed, the main and
the back up with automatic switchover in case of loss of signal of the main
system.
3.2.7
Wicket Gate Feed Back and Other Devices.
The feed back between the actuator and regulator cubicles and wicket gate
servomotors shall be of electronic/ electrical type. The cables for feed back
shall be as short as possible and shall be properly protected against injury
and damage. The load feed back for the governor shall be provided by
position sensing devices and from the CT's and PT's provided in the bus bar.
3.2.8
Software Program Features.
1. The software for the microprocessor based speed governor shall be
capable of quick program running. In case of any power supply failure the
program and parameters shall remain indefinitely retained.
2. The governor shall have auto test program to check permanently the
correct operation of the main governor components. The correct execution
of the software shall also be permanently checked for which suitable
'Watchdog' monitoring circuit shall be provided
3. The software shall prohibit the programming of the parameters beyond the
allowed values.
3.2.9
Other Provisions:
The speed governor shall be provided with the following provisions:
a) Facility of data communication i.e. exchanging information through serial
communication link.
b) Provision for data exchange with automatic systems or the power station
for remote indication logic information & remote control etc. if there are
17
any data exchange that can not be realised through the serial
communication link.
3.2.10
Maintenance/ Replacement Provisions:
The digital programmable electronic governor shall have modular construction
with suitable configuration to enable quick and easy maintenance
/replacement in case of fault. The maintenance and operation of the speed
governor shall be feasible by use of an automatic internal checking program
and also step by step manual internal checking program with the help of
instruction manual. Adequate number of test points & Light Emitting Diodes
on the front face of each card for an easy detailed analysis of each subassembly shall be provided.
3.2.11
Fail Safe Provision:
The electronic governor and hydraulic actuator shall be designed on the basis
of fail safe principles. The necessary details shall be furnished along with the
bid.
3.2.12
Governor Operating Time Adjustment
The wicket gate closing and opening time adjustment shall be possible
without dismantling the main distribution valves of the actuator. Details shall
be furnished along with the bid.
3.2.13
Control, Indication and Annunciation Scheme:
The tentative scheme of distribution of various governor controls as indicated
in the following list which may not necessarily be complete and may be
amended & finalised during detailed designing stage. The following indicating
instruments shall be mounted on the front face of the actuator cabinet.

Tachometer

Gate position and gate limit (duplex)

Load control position.

Speed adjustment position.

Governor system oil pressure.
The following controls shall be provided on the front face of the actuator
cabinet:

Gate limit setting device

Generator brake control switch (On, Off & Automatic)

Speed droop setting device.

Speed adjustment device.

Load control switch.
18

Automatic/Test/off/Manual control switch.

Unit stop push button.

Unit start push button.

Emergency shut down push button

MIV open push button.

MIV close push button.
The following indicating lights shall be provided on the front face of the
actuator cabinet.

Unit ready for start.

Unit start.


Unit excite.
Unit spinning.

Unit ready to accept load.

Main breaker 'ON'.

Unit synchronised/paralleled.

Unit loaded.

Servomotor gate lock 'ON/OFF'.

Generator brakes switch on 'Auto' position.

Generator brake 'ON/OFF'.

Speed sensor failure.

Auto/manual indication.
In addition to above the cabinet shall have the following indicators:

Governor pump-I 'ON'.

Governor pump-II 'ON'.

MIV open.

MIV closed.

MIV in transit

Oil pressure too high.
19

Oil pressure too low.

Oil level high.

Oil level low.

Brake 'Off'.

Brake 'ON'.

MIV by pass valve open.


Oil temperature high.
Lubrication Oil Pump ON
All the above indications shall be LED type/binary matrix type.
The supplier shall co-ordinate with the supplier of control and monitoring
system for engineering control system etc.
3.2.14
Actuator Control and Instruments
The following controls and instruments shall be provided in the actuator:
1. Gate position and gate limit indicators:
A mechanical gate limit indicator and gate position indicator of duplex type
shall be provided. These indicators shall have the provision to be adjusted
at site to obtain correct indication of turbine gate position.
The manufacturer shall supply the necessary transducers wired in the
cabinet for remote indication of the gate position & gate limit at the power
house control room & UCB. The output of these transducers shall be
proportional to the gate position and gate limit.
The gate limit control device shall limit the degree of wicket gate opening
at any position within the full range of wicket gate travel from the control
room & UCB.
2. Speed Adjustment Control and Indication:
A device for adjusting the speed set point of the governor when the
generator is isolated from the system shall be provided, operated
manually at the actuator and electrically controlled by the synchronising
equipment.
For manual control, a dial type indicator shall be provided which shall
cover a range of speed setting from 85% to 110%.
At least four limit switches shall be provided to control speed adjustment
and prevent the speed motor to over-travel the synchronous speed after
the main breaker is closed.

Open at and above 5 percent over synchronous speed.
20

Open at and below 15 percent below synchronous speed.

Open at and above synchronous speed.

Open at and below synchronous speed.
3. Load Adjustment Control and Indication:
Necessary device for adjusting the output set point of governor when main
breaker is closed and unit is synchronised along with two feedback
systems, one from wicket gate and the other from generator output shall
be provided with a provision to select any one feedback signal at site.
4. Speed Droop Control and Indicator:
A speed droop control device which operates when main breaker is
closed and determine the change in output if speed deviates from the
synchronous speed shall be provided along with manual control from 0 to
10% and a speed droop indicator with a calibrated dial to indicate the
speed change for which the unit is adjusted.
5. Manual Gate Control.
The provision shall be made to manually control the wicket gates from the
control cabinet, for local control, for testing and the unit can continue in
operation, should the electronic circuitry, transducer or transducer valve
be inoperative. The transfer of control from automatic to manual and vice
versa shall be possible while unit is in operation.
The provision to select the manual/ automatic control shall be made from
the actuator cabinet or from the remote control system. The automatic
shutdown protection shall be available under manual control.
6. Automatic Start, Shut down and Speed-no-load.
Necessary provision for automatically starting the turbine, shut down the
turbine and for emergency & catastrophic shut down of the turbine or
operation of automatic protection devices for the generator, turbine and
governor shall be made.
The automatic speed-no-load device, when actuated, shall limit the
turbine wicket gate to slightly above the speed-no-load position. The
device shall permit manual and automatic shutdown of the unit to speedno-load at any time & shall be such that the wicket gate are again
governed by the speed responsive element on reaching the speed-no
load position. The automatic start-up/shut down shall be initiated by
momentary closure of contacts. Synchronising action shall then be
initiated from the governor when the unit attains 90 percent of the speed.
The speed -no-load shutdown solenoid shall be energised after the main
breaker closes.
7. Generator Brake Control.
21
A combination hand-operated and solenoid operated valve to control the
operation of the generator brakes shall be supplied and mounted in the
actuator cabinet.
In the automatic mode the gate position switches and speed switches
shall prevent the application of the brakes until the wicket gates are fully
closed and the speed has decreased to less than 20% of rated speed .It
shall be possible to apply brakes continuously below 20% speed after an
adjustable period of time by means of the automatic control. The brakes
shall be automatically released after the adjustable period of time
sufficient to assure that the unit has been brought to a complete stop.
When the control switch is in the 'Automatic' position, a separate contact
shall be closed for inter lock in the auto-start circuit. A pressure switch
shall be provided in the airline to the brake cylinders with contacts to open
as an inter-lock to prevent start up whenever the brakes are on. The
pressure switch shall be provided to energise the alarm when air pressure
is low.
8. Tachometer:
The speed sensing device shall be fitted in governor and signal for speed
shall be taken from potential transformer.
9. Oil Pressure Gauge:
The necessary oil pressure gauge shall be provided on the actuator to
indicate the pressure in the governor oil pressure tank.
10. Gate Position Switch:
Sufficient number of contact switch assembly operated by the servomotor
position transducer shall be provided. Each contact shall be adjustable
type at any point from zero to 100 % gate opening as per the site
conditions. Contacts shall be electrically isolated, ungrounded and
suitable for dc, operation.
11. Cabinet Light.
Suitable vapour proof lighting for 240V, 50Hz ac. Fixture preferably C.F.L.
(Compact Florescent Light) to illuminate the interior of all the cabinets
shall be provided.
12. Governor Time Adjustment.
The necessary provision shall be made to adjust the opening and closing
time of the wicket gates between 4 seconds and 20 seconds for full gate
opening/closing stroke and these adjustments shall be lockable.
13. Actuator Lock:
Provision shall be made to lock the turbine wicket gate while maintenance
works on the governor’s electronic amplifiers is to be carried out. The lock
will automatically apply on withdrawal of an amplifier card and disengage
on replacement of the same card. The device shall allow the closing of the
wicket gates at any time by action of the gate limit or the shut down
22
solenoids. The automatic shut down protection shall be maintained during
actuator lock.
3.2.15
Electronic Section:
The electronic cards shall be housed in the actuator cabinet and shall be
accessible from the front of the cabinet after opening the cabinet door.
The governor shall be Proportional, Integral and Derivative (PID) type. The
following adjustment range shall be provided:
Integral gain
0 - 10 second
Proportional gain
0 - 20
Derivative gain
0 - 2 second
All the adjustments shall be calibrated in absolute terms.
The governor shall be fitted with the devices to improve the response time of
the generator unit to change in load adjustments and bypass the normal
proportional, integral and derivative amplifiers.
3.2.16
Speed Switches:
A mechanical over-speed switch shall be provided on the turbine-generator
shaft to operate automatically as the unit speed rises slightly above the
maximum speed rise allowed on full load rejection and shall trigger directly an
emergency shut down valve in the hydraulic pressure circuit. The operation of
the switch shall bypass all the electrical signals and action of other protective
devices and give command to close the wicket gates. An auxiliary contact
switch on the governor cubicle shall be provided to annunciate operation of
the mechanical over speed switch.
The electronic speed switch shall be provided and mounted on the electronic
cabinet of governor for following functions:
(a) Over-speed Protection:
i)
To cause unit shut down through shutdown solenoid via protection
circuits at and above guaranteed speed rise.
ii)
To cause emergency shut down of the unit through certain specific
protection circuits and/or when unit speed increase beyond 140
percent.
iii)
In the event of catastrophic conditions and speed rising to 150 percent
and above simultaneous command shall go to emergency solenoid
valve and Spherical valve control cabinet for closure.
The setting of various speed switches for over speed protection are
tentative and shall be decided at detailed engineering stage.
b)
Excitation and Synchronising
23
Two sets of contacts shall be provided to close at and above 90% of
the rated speed and wired to the governor terminal block.
c)
Brake Control:
The generator brake shall be arranged to activate at 20% of the rated
speed and the wicket gates are closed when unit CB is open.
d)
Forced lubrication;
To cause forced lubrication of thrust bearing from zero speed to
predetermined speed and vice-versa.
e)
Zero Speed:
The necessary set of contacts shall be provided and wired upto the
terminal block of governor cubicle to indicate unit stopped and creep
indication. The creep indication is to be provided by the supplier.
The space shall also be provided for additional switch.
3.2.17
Electrical Power Supply
The power for the governor shall be drawn from two source i.e. primary
source shall be 230 V, single phase 50 Hz and secondary shall be 110 V,
D.C. supply.
The necessary power conversion equipment shall be provided by the
governor supplier capable of drawing power from the primary or secondary
sources and it should have necessary redundancy. The switch over from
primary to secondary will follow automatically on the failure of the primary
supply or converter and will return to primary source automatically following
restoration of primary source. The switchover shall be smooth and shall not
cause any mal-functions. The power conversion equipment shall include
transient voltage protection for surge voltage up to 6kV.
The unit shall be shut down if the 110 V dc supply fails. Failure of the power
conversion equipment to deliver low voltage power to the governor shall
cause shut down of the unit when the governor is on Auto mode.
3.2.18
Gate Position Feedback:
The necessary displacement transducer will be provided to measure
servomotor stroke and thus the wicket gate position. The output from the
transducer shall be used to operate the gate position switches and for gate
position indication.
3.2.19
Governor Oil Pumps:
Two main motor driven oil pumps shall be provided in each governor and
having a capacity of not less than 1.5 times the total oil volume of the wicket
gate servomotor, MIV servomotor, brake servomotor and one jockey pump
having a capacity in excess of the expected leakage of the distribution valve.
The main pump shall run continuously without overheating and supply oil to
the sump or accumulator. Necessary oil strainer shall be fitted in the suction
line of each pump.
24
The motor pump unit shall be fitted on the sump tank and control switches/
indicating lamps shall be mounted on the front panel of actuator. The motor
shall conform to IEC standard, with class 'F' insulation and having low starting
current.
The automatic pressure operated controls shall be provided to start and stop
the pumps when the pressure rises or drops to pre-determined points.
The two main oil pumps shall be arranged with echelon controls to be
operated either independently or together with one pump used for normal
operation and the other arranged to start with a drop in oil pressure. Manual
control switch shall be provided to select one of the two pumps as the lead
pump. An alarm shall be provided to indicate continuous running of the lag
pump over on adjustable period of time. All valves and mechanisms shall be
accurately set and tested in the shop before delivery.
Each governor pump shall be provided with an adjustable temperature switch
with two electrically separate contacts suitable for operation at 110 V dc.
located in the pump suction side for governor oil high temperature alarm.
3.2.20
Pressure Tank:
A pressure accumulator tank of steel plate welded construction shall be
provided for each governor in accordance with the requirement of the relevant
International Code for Pressure Vessels. The size of the tank shall be such
that it shall be possible to operate the wicket gates and MIV 3 times (2
'C'+1'O') without re-charging the pressure accumulator. The pressure tank
shall be pressure tested in the shop in accordance to the requirement of
relevant standards.
The necessary pressure gauge, sight gauges, manual shutoff and ball check
valve and safety relief valve shall be provided on the pressure tank.
The pressure tank shall be provided with nitrogen piston/bladder accumulator
of suitable capacity. The manufacturer shall supply all necessary piping,
fittings, solenoid controlled valves, pressure and level switches required for
this system. The solenoid shall be suitable for operation at 110 V dc and
completely wired.
An adequate sized manhole with suitable oil resistant gasket shall be
provided. The tank shall be painted on both sides.
In addition to pressure switches required for echelon control the following
pressure switches shall be provided and connected to each pressure tank.


Governor oil low pressure alarm to the station annunciator, one
contact to close on low pressure.
For extreme low pressure trip and for unit start inter lock.

Low oil level for unit shut down.

Extreme low oil level.
All contacts shall be adjustable, electrically separated and suitable for 110 V
dc operation.
25
All pressure and level switches shall be provided with individual shut off
valves and bleed valves as necessary.
3.2.21
Sump Tank:
The governor system shall be supplied with a sump tank of sufficient capacity
to hold at least 10 percent more than the total quantity of oil in the entire
governor system. The sump tank shall be provided with a manhole,
connection for venting and overflow. Suitable connection for oil purifier,
draining and filling shall be provided. A vertical filter screen shall be arranged
to divide the sump tank into 'clean' and 'dirty' oil compartments. All the
strainers shall be readily removable for cleaning. Low and high level switches
and oil temperature switch shall be provided on the oil sump tank.
3.2.22
Pipes and Fittings
All pipes, fittings, all type of valves including non-return valves for connection
between servomotors, oil sump tank, pressure accumulator and governor
shall be provided.
3.2.23
Spares
The following spares which comprise the total required for all the four
governors under this contract shall be furnished. The price for the spare parts
shall be stated separately in the Bid. A set is defined as the total number
required for one governing system.
A. GOVERNOR
1.
Control valves of each (main distributor valves as
well as pilot valves)
1set
2.
Filtering element for governor
4nos.
3.
Speed sensing device (complete)
1no.
4.
Complete set of all plug in units, printed circuit cards
and transducers for one governor furnished.
1set
5.
Pressure and position transducers of each type used
1set
6.
Circuit breakers and control switches of each type used
1set
B. OIL PRESSURE UNIT (OPU)
1.
Pressure oil pump-motor set
1No.
2.
Nitrogen filled cyllender
1No.
3.
Motor bearings
1set
4.
Safety relief valve
1No.
5.
Un-loader valve
1No.
6.
Oil filter for oil sump
1No.
26
7.
Level relays for OPU
1No.
8.
Glass pipe for sight gauge
1No.
9.
Pressure relay
1No.
10.
Sediment level sensor
1No.
C. COMMON TO GOVERNOR AND OPU
1.
Resistance temperature detector of each type used
1set
2.
Proximity switches of each type used
1set
3.
Pressure gauge of each type used
1set
4.
Dial type thermometer of each type used
1set
5.
Rubber cords, o-rings sealing, packing, gaskets etc.
1set
6.
Indicating instrument of each type used
1set
7.
Solenoid valve of each type used
1set
8.
Maintenance valve of each type used
1set
9.
Indicating lamp with lamp assembly
2sets
The Bidder shall include with his bid an itemised list and prices of all of
additional spare parts he recommends to be purchased. Purchase of any or
all of the additional recommended spare parts shall be at the option of the
owner.
3.2.24
Maintenance Requirement.
One complete set of special tools, which may be necessary for convenient
assembly and dismantling of governors shall be furnished. The tools shall be
furnished in a suitable toolbox, or on a suitable wall mounted panel stamped
for identification and intended use.
3.2.25
Shop Assembly and Tests:
3.2.25.1
General:
The governor and auxiliary equipment shall be completely assembled in the
manufacturer/bidder's shop and tested, in so far as practicable. The pressure
tanks and piping shall be shop hydrostatic pressure tested at a pressure 1.5
time the maximum allowable working pressure. Before painting, the sump
tank shall be tested for leakage by compressed air and a soap solution or
other approved means.
3.2.25.2
Operational Tests:
Operational tests shall be performed on all of the equipment or devices to
demonstrate that these function properly. Adjustable devices shall be
checked for range of adjustment and given final adjustment in so far as
27
possible in the shop. The oil pressure pump, unloading valve, relief valve and
starting and stopping pressure relays shall be tested and accurately set in the
shop. Electrical devices shall be given and shall withstand dielectric tests in
accordance with applicable provision of IEC recommendations or other
approved standards. Where applicable, parts of the governors equipment
shall be properly match marked and doweled during shop erection to facilitate
correct assembly and alignment at site. The governing equipment shall be
shipped with parts complete and ready for operation.
3.2.25.3
Shop Performance Tests.
The governors shall be shop tested to demonstrate that these shall meet the
requirements as specified. Performance requirements, in respect to dead
band time, dead band speed and speed response. At least 60 days prior to
the performance tests, detailed descriptions of the procedure and equipment
to be used shall be submitted to the Engineer-in-charge. The charts shall be
marked for identification of the test performed, traces labelled and
incremental values of the recorded variable marked on the charts.
4.2.25.4
Witnessing of shop assembly and tests.
The shop assembly tests shall be witnessed by the representative of the
owner as per the approved inspection and quality assurance plan. All the
necessary material, labour, test equipment and instruments shall be furnished
by the bidder.
3.2.26
Installation:
The bidder shall place, level and fasten the governor equipment on the
concrete foundation. Interconnecting piping between various equipment, such
as between the actuator, oil pressure unit, and servomotors and restoring
mechanisms between the governors and servomotors, including supports and
hangers, shall be supplied and installed by the bidder. All rust preventive
compounds shall be removed from the equipment before initial operation, and
any rust which may have formed on the parts shall be carefully removed. The
oil piping, oil sump tank and pressure tank shall be thoroughly cleaned and
flushed before governor oil is placed in the system. The bidder has to do all
work related to erection, testing and commissioning of governor complete in
all respect. Supply of all consumable and other material required for
installation etc. shall be in the scope of bidder.
3.2.27
Field testing
The bidder shall furnish a complete outline of the proposed method and field
procedures to be followed for the turbine and governor tests, including a list of
equipment and instruments to be used, to the Engineer-in charge for review
not later than 60 days prior to the date on which the first turbine and governor
is to be ready for testing.
All necessary materials and labour for performing all the above tests shall be
provided by the bidder.
All test equipment and instruments, shall be furnished by the bidder and will
remain the bidder's property after the fulfilment of all field tests.
The test at site should at least include the following:
28
-
Tightness tests on all pressure oil piping in connection with the turbine
equipment
-
Pressure tests on all pressure oil piping (in connection with the
governor equipment) and all pressure piping system shall be
hydrostatic tested at a pressure 1.5 times than the maximum
operating pressure after installation.
-
Start-up, load rejection and load acceptance tests including speed and
power regulation test.
-
The tests shall be co-ordinated with the test for turbine, butterfly valve,
generator and other equipment.
Following parameters shall be measured recorded as function of time.

Oil pressure in servomotors

Turbine speed

Servomotors stroke

Pen stock pressure

All other tests on the governor equipment as deemed necessary by
the bidder or Engineer-in-charge.
The tests shall be carried out in accordance with IEC publications and the contractor
shall furnish a complete report of the field tests of the equipment.
29
SECTION-IV
OVERHAULING / REPAIR OF GENERATOR, TURBINE, TURBINE SHAFT,
BEARINGS AND REPLACEMENT OF BEARING SLEEVES
4.1
Scope
i)
ii)
iii)
4.2
Complete overhauling / repair of generator, turbine including repair of shaft
and bearings, of four units including all services, labour, tools and tackles
required for dismantling and assembly, including design, reverse engineering,
manufacture, manufacture through reverse engineering, site testing, delivery,
erection, testing & commissioning, field acceptance test, handing over to
owner/HPSEB Ltd. of the above system.
Dismantling/removing of existing (4) No.’s bearing sleeves of francis type
Turbine all services, labour, tools and tackles required for dismantling
including carriage, stacking at Owner’s store/ yard.
Design, engineering, manufacture, shop assembly & testing before dispatch,
packing and forwarding, transportation, insurance, handling, delivery, storage
at site, erection, testing & commissioning of four (4) No.’s bearing sleeves of
francis type Turbine as detailed in this specification and handing over to
HPSEB LTD. including all services, labour, tools and tackles
Turbines
The turbines are horizontal shaft Francis turbine directly coupled with the
generators designed and supplied by M/s Jyoti. Ltd. Baroda (Gujarat). Each
turbine consists of spiral casing with integral stay ring, guide apparatus with
regulating mechanism, turbine shaft, runner, shaft gland seal, pedestal type
thrust cum guide bearing, pedestal type 2nd guide bearing, coupling for turbine
and generator, flywheel & pulley, discharge pipe and draft tube etc. Technical
parameters of the turbines are given below :-
i)
No. of turbines
4 (four)
ii)
Type of turbine
iii)
Setting
400 HFIV-500, Francis
turbine Jyoti Make.
Horizontal
iv)
Turbine output
750 HP
v)
vi)
Net head
Rated speed
79 meters
1000 rpm
vii)
Runaway speed
1700 rpm
viii)
Specific speed
116.3 rpm
ix)
Runner Diameter
414 mm
x)
BF valve diameter
500 mm
30
xi)
4.2.1
Spiral inlet diameter
414 mm
Spiral Casings:Spiral casing is cast fabricated with integral stay ring. The joints of spiral
casing with butterfly valve outlet pipe and draft tube bend pipe are leaking.
The outer and inner surfaces of the casing are severely corroded.
4.2.2
Guide Apparatus:Guide apparatus consists of turbine cover, lower ring, twelve guide vanes with
upper/lower bushes, levers, links and regulating ring. Guide vanes of all the
machines have been repaired a number of times resulting in change in their
original profile and other dimensions. It is observed that the guide vanes do
not close properly and openings between consecutive guide vanes are not
uniform. This leads to non uniform flow of water, reduced efficiency and
increased vibrations of the machines.
4.3
Performance Requirements of turbines :-
4.3.1
After overhauling/ repair as described in section 4.1 each turbine shall be able
to give, at rated net head of 79 m, rated output not less than 530 kW at rated
speed of 1000 rpm. Capacity test shall form the basis of successful
completion.
4.4
Performance Requirements of generators :After overhauling/ repair as described in section 4.1 each generator shall be
able to generate, rated output not less than 500 kW at rated frequency of 50
Hz. Capacity test shall form the basis of successful completion. Any
modification required to make compatible AVR with existing generator shall
also be carried out by contractor under this contract.
4.5
Bearing Sleeves
4.5.1
Scope: -
4.5.2
Technical requirements :Bearing sleeves shall have identical metallurgical properties as that of original
and should be capable of safe operation at all loads and operating conditions.
Details of the existing bearing sleeves shall be collected by contractor from
the site.
Bidders shall visit the site and assess the repair / overhauling
requirements of each machines and quote accordingly. No
deviation over the quoted overhauling / repair scope shall be
allowed at later stage.
31
SECTION-V
OIL LUBRICATING SYSTEM AND COOLING WATER SYSTEM
5.1
Scope
This section of the specification cover the following scope of works: i)
ii)
5.2
Dismantling/removing of existing four (4) No.’s oil lubrication system and four
(4) No.’s cooling water system of francis type Turbine all services, labour,
tools and tackles required for dismantling including carriage, stacking at
Owner’s store/ yard.
Design, engineering, manufacture, shop assembly & testing before dispatch,
packing and forwarding, transportation, insurance, handling, delivery, storage
at site, erection, testing & commissioning of four (4) Nos. oil lubrication
system and four (4) No.’s cooling water system of francis type Turbine as
detailed in this specification and handing over to HPSEB LTD. complete with
accessories, equipment, devices, piping, instruments, cabling and wiring etc.
including all services, labour, tools and tackles.
Grease / oil lubricating system
Each turbine shall be provided with an automatic grease/oil lubricating system
complete with grease/ oil reservoir two motor operated grease / oil pumps
with motors, starters, switches, timers, pipes and fitting for lubricating all
points. One motor pump set shall operate on AC power supply and other
motor pump by DC power supply.
The system shall supply measured quantities of grease/ oil as often required
to all bearing surfaces of levers, links, rods, wicket gate stems and all other
parts to be lubricated. Different timing devices shall be used for fixing the
different periods required for points requiring frequent lubrication such as
wicket gate stems and points requiring in-frequent lubrication.
Indicators shall be provided at all greasing points to indicate that the
lubrication is being received.
A pressure switch shall be provided to shut down the system in case of any
block in the lubrication system resulting in high pressure. An alarm contact
shall be provided for giving alarm in case of system failure.
The grease reservoir shall have a capacity to store grease for 240 hours of
operation. An electrically operated transfer pump shall also be supplied for
transferring grease from barrels to the reservoir.
Suitable provisions shall be made at all greasing points to receive grease by
manual application. A portable grease pump shall be supplied for the station,
All material such as pipes, fittings, supports etc. which are necessary for
making the system complete in all respect shall be provided.
The control panel with control indication, starting buttons, fault indicator and
necessary contact for the PLC control shall be provided. The panel shall be of
wall mounted.
32
5.3
Cooling water system
The maximum temperature of the inlet water at site is 200C. The turbine
supplier shall design and supply the complete cooling water system catering
to the requirements of the entire turbine guide bearing, turbine seal and
generator bearings. Cooling water shall be tapped off from the penstock
through necessary pressure reducers/diffusers etc.
The system for each unit shall be complete with isolating valves, manual/self
cleaning type strainer, flow measuring device, pressure gauges, piping and
fittings. Self cleaning strainer, and associated items shall meet the cooling
water requirement of each unit .
Strainers shall be fitted with pressure switches to give alarm in case the
pressure differential across inlet outlet exceeds a preset value. Pressure
gauges shall also be provided to indicate water pressure at its inlet and outlet.
33
SECTION-VI
REPLACEMENT OF MANUAL VOLTAGE REGULATORS WITH AUTOMATIC
VOLTAGE REGULATORS
6.1
Scope: This section of the specification cover the following scope of works: i) Dismantling/removing of existing four (4) No.’s manually controlled voltage
regulators, all services, labour, tools and tackles required for dismantling
including carriage, stacking at Owner’s store/ yard.
ii) Design, engineering, manufacture, shop assembly & testing before dispatch,
packing and forwarding, transportation, insurance, handling, delivery, storage
at site, erection, testing & commissioning of four (4) No’s. digital type
automatic voltage regulators as detailed in this specification and handing over
to HPSEB LTD. complete with accessories, equipment, devices, instruments,
cabling and wiring etc. including all services, labour, tools and tackles.
6.2
Technical requirements of Automatic Voltage Regulator:
The voltage regulator shall be of quick acting microprocessor based and shall
respond continuously and instantaneously to correct any change in generator
voltage. It shall maintain the generator voltage for steady state load
conditions without hunting, with 0.5% accuracy for any excitation with in the
operating range of the generator. For steady state conditions with the
generator circuit breaker open the regulator shall maintain the generator
terminal voltage at or below 110% of its setting for speeds ranging from rated
speed to an over speed of 130% rated speed. An excitation limiting control
shall be provided to limit the generator voltage to maximum 125% of rated
voltage in the event that the AVR is tripped co-incidentally with 110% load
rejection and generator speed rising to runaway speed.
The AVR shall be provided with over & under excitation limiters. The
intervention of the limiters shall not cause perceptible deviations or
oscillations of the generator active & reactive power. Such devices shall allow
the regulator to reduce the excitation voltage to zero in order to prevent over
voltage in case of operation, under line reactive load conditions and over
speeding of the unit. The characteristics of the under excitation limiting curve
shall match the static and dynamic stability curves of the generator.
The following features shall be included: Stator current limiter.
Field current limiter.
Load angle limiter.
The field current limiter shall act on AVR with a time delay so as not to disturb
transient response of the system during voltage dips/faults. A slip stabilizer
unit shall be provided to surpass the low frequency power oscillation during
the operative conditions.
The AVR shall be equipped with a sensitivity-adjusting device and with
adjustable voltage droop compensation (compounding). The voltage
regulating system shall include device for improving the damping of active
34
electromechanical oscillations. These devices shall operate to supplement the
voltage regulation action by addition of an additional control signal into the
excitation system input. This supplemental input signal shall influence the
excitation system a.c. to cause a change in field current of the machine for
stabilized operation.
After, the generator voltage attaining initial maximum value neglecting the
instantaneous rises following any load rejection upto 110% of rated load, AVR
shall restore the generator terminal voltage to a value not more than 5%
above or below the voltage being held before load rejection and shall
maintain the voltage within these limits throughout the period of the generator
over speed.
The voltage setting device provided shall be of the solid state digital type
having a range of 10% for local & remote control and indication. For testing
purposes setting of 10% to 115% shall be adjustable at the AVR cubicle.
The AVR system shall be capable of manual and automatic operation.
AVR system shall be compatible with existing generators. Any
additional hardware required for compatibility with generator shall be
supplied by the contractor.
The change over from automatic to manual control shall be performed
automatically following a failure of the regulator when operating on automatic
control. The generator voltage shall be controlled with in the range of  10%
of rated voltage. A static follower shall be provided so that, in the change over
from automatic to manual control, it prevents the excitation current from
deviating more than 5% of no load excitation current under steady state
conditions. An alarm and visual indication shall be provided to indicate
change from "AUTO" to 'MANUAL'. The automatic and manual control circuit
shall be fully independent. Local & remote control shall also be possible.
6.3
Mandatory Spare Parts: - Following mandatory spares shall be supplied
alongwith main equipment:One (1) Set of all plug in units, printed circuits cards, power supply units,
protection devices and transducers for the excitation equipment and
automatic voltage regulator.
One (1) Sets of thyristor complete with fuses and all accessories.
One (1) Field circuit breaker.
One (1) Set of discharge resistors.
One (1) Set of relays, circuit breakers, contactors, switches, fuses, indication
instruments etc., of each type used.
One (1) Set of small parts, subject to wear and tear such as gaskets, valve
components, etc.
35
SECTION-VII
REPLACEMENT OF 30V, 400 AH BATTERY, BATTERY CHARGER AND
DCDB WITH 110 V, 200 AH BATTERY, BATTERY CHARGER AND DCDB
7.1
Scope
This section of the specification cover the following scope of works: i) Dismantling / removing of existing battery charger, battery bank and DCDB all
services, labour, tools and tackles required for dismantling including carriage,
stacking at Owner’s store/ yard.
ii) Design, engineering, manufacture, shop assembly & testing before dispatch,
packing and forwarding, transportation, insurance, handling, delivery, storage
at site, erection, testing & commissioning of battery bank, battery charger and
DCDB as detailed in this specification and handing over to HPSEB LTD.
complete with accessories, equipment, devices, instruments, cabling and
wiring etc. including all services, labour, tools and tackles.
7.2
7.3
Technical Requirements of Batteries
General Description : The 110V, 200AH Lead Acid Type storage batteries with Plante Positive
Plates are required for meeting the D.C. load requirements of Power House.
7.4
Standards: -
7.4.1
The equipment covered under this specification shall comply with the
requirements of latest editions of the following Indian Standards as amended
to date except where specified otherwise: IS : 1146
Rubber and plastic containers for lead acid batteries.
IS : 1652
Stationary cells and batteries lead acid type with Plante
positive plates.
IS : 266
Sulfuric acid.
IS : 8320
General requirement and method of tests for lead acid storage
batteries.
IS : 8320
General requirements and method of tests for lead acid
storage batteries.
IS : 6071
Synthetic separators for lead acid batteries.
IS : 3116
Sealing compound for lead acid batteries.
7.4.2
Equipment meeting with any other authoritative standards, which ensure
equal or better quality than the standards mentioned above are also
acceptable. Where the equipment conforms to any other standards other than
those mentioned above, salient points of difference between the standards
adopted and standards mentioned shall be clearly brought out in the tender.
Battery : -
7.5
7.5.1
Type: The Plante positive plates shall be of the pure lead lamelle type with plante
formation. The negative plates shall be of pasted construction and assembly
shall consist of sturdy lead alloy grid filled with active material. The
36
7.5.2
7.5.3
7.5.4
7.5.5
7.5.6
7.5.7
7.6
7.6.1
7.6.2
construction shall be used to ensure good mechanical retention of the active
material and maximum electrical conductivity throughout, the life of the cell.
Capacity: The capacity of each cell will be based on 10 hours discharge rate for an end
voltage of 1.85 volts at 270C. The nominal voltage will be 2 volts. Voltage of
each cell after complete discharge should not fall below 1.85 volts. The
overall voltage across the load during float as well as boost charging shall not
be more than 110% of the nominal voltage i.e. 110V.
Number of cells: The battery consists of a total of 55 cells. The Tenderer shall give the
optimum rate of charge for float charging the battery. The battery shall be
operated alongwith two rates charger.
Cell Terminals : All cell terminals shall have adequate current carrying capacity and shall be of
lead alloy or lead alloy reinforced with copper core insets. Cell terminal posts
shall be supplied with acid resistant connectors, bolts and nuts.
Containers: The containers for cell shall be of transparent plastic. They shall have a neat
finish and shall be free from leaks. The surface of container shall have a finish
substantially free from blisters, rough spots, scales, blowholes and other
imperfections or deformations. Electrolyte level lines shall be marked on all
four sides of each container.
Electrolyte: The electrolyte shall be battery grade sulphuric acid. The battery shall be
transported empty and dry. The required quantity of battery grade electrolyte
concentrated sulphuric acid, to be diluted at site to serve as electrolyte for first
filling of the cells, shall be supplied in separate non-returnable containers
including 10% extra quantity of electrolyte. The quantity of electrolyte
alongwith its specific gravity shall be specified.
Venting Device: Each cell shall be provided with a venting device at the top which shall be
anti-splash type with more than one exist hole and shall allow gases to
escape freely but shall effectively prevent acid particles or spray coming out.
These shall also provide an opening for addition of distilled water as required
to top up the electrolyte. The vent plugs shall be explosion proof. The
construction details of vent plug shall be provided in the tender.
Installation of Batteries: The battery shall be mounted on wooden racks in the battery room. Acid
resistant insulation between cell and racks shall be provided. The racks shall
be so arranged as to present a neat and aesthetic appearance. The
arrangement shall be subject to approval of the Purchaser. Each cell as well
as its location shall be numbered for proper record of maintenance and
operation. Termination polarity of each cell shall be clearly stamped as
positive and negative. The connections between the cells shall be bolted type.
The bolts and nuts and connectors will be effectively lead coated to prevent
corrosion and should be of adequate capacity to carry maximum current. As
powerhouse lies in a seismic zone, the Tenderer/Manufacturer shall give
specific recommendations in his offer for installation of batteries in such a
fashion that these are not damaged due to seismic forces. The battery bank is
required to be erected/installed on the existing wooden racks in two tier
formation in a room of 6 x 3.25 m size approximately.
Fitting and Accessories : The Tenderer shall provide all the fittings and accessories required for the
satisfactory installation, operation and maintenance of the battery, even if
37
these are not specifically mentioned in this specification. The following
accessories shall, however be supplied with the battery set: Sr. Description
Quantity
No.
i)
Inter cell and inter row connector with nuts and bolts. 1 set
Inter cell connector shall provide about 12mm space
between cells. These shall be lead plated copper
connection.
ii) Hydrometers complete with accessories (Temperature 2 nos.
Correction charts).
iii) Thermometer for measuring electrolyte temp.
2 nos.
iv) Analogue type cell testing voltmeter scaled 3-0-3V, 2 nos.
complete with leads.
v) Glass funnels
2 nos.
vi) Acid resistant jug
2 nos.
vii) Rubber gloves
2 pairs
viii) Rubber aprons
2 nos.
ix) Rubber boots (knee high)
2 pairs
x) Nylon brushes with stout bristles for cleaning 2 nos.
connections
xi) Identification plates for cells with location number of cell
1 set
7.6.3
7.6.4
7.6.4.1
a)
i)
ii)
iii)
iv)
v)
b)
i)
ii)
iii)
iv)
v)
vi)
vii)
c)
i)
ii)
iii)
Distilled Water Still: Distilled water still, electricity operated having output of 2.5 litres/hour
Suitable for working on 230 volts, 50Hz. A.C. Single phase complete in all
respects. Necessary supporting stands shall also be supplied.
Tests: The battery shall comply with the requirement of routine, acceptance and type
tests as per IS: 1652 and 8320. The following shall be routine, type and
acceptance tests :Routine Tests :Verification of conformity of material.
Verification of constructional requirement.
Verification of dimensions.
Verification of marking and packing.
Air pressure test.
Type Tests :The following shall constitute type tests and shall be carried out in the
sequence given below: Verification of constructional requirements.
Verification of marking.
Verification of dimensions.
Test for capacity - Test for voltage during discharge.
Ampere-hour and watt-hour efficiency tests.
Test for retention of charge
Endurance test.
Type test shall be carried out on two cells. One cell shall undergo all tests
except endurance tests while the other would undergo endurance test
preceded by a capacity test.
Acceptance Tests :The following shall constitute the acceptance tests: Verification of marking.
Verification of dimensions.
Test for capacity.
38
iv)
Test for voltage during discharge.
Acceptance test shall normally be carried out at the discretion of the
Purchaser on each cell after installation at site. The date and place of testing
shall be subject to agreement between the Purchaser and the supplier.
In case the manufacturer has conducted Type test earlier on the similar
product, the type test certificate shall be submitted .
7.7
Technical Requirements of Battery Charger :-
7.7.1
Equipment Description
(a)
The battery chargers as well as their automatic regulators shall be of static type.
Battery chargers shall be capable of continuous operation at the respective rated
load in Float mode, i.e. Float charging the associated Lead-acid plante high
discharge type Batteries while supplying the DC loads. The batteries shall be float
charged at 1.4 to 1.5 Volts per cell. The charger shall also be capable of Boost
charging the associated batteries at 1.42 to 1.7Volts per cell at the desired rate. The
chargers shall be designed to operate, as mentioned above, up to an ambient air
temperature of 500C. Tapping arrangement in the battery bank shall be provided to
limit the over voltage for supplying load within allowed voltage range under boost
charge conditions. The charger should automatically switchover to float charger & to
boost charger when the specified limit of voltage is approached. However, necessary
time circuit shall be used to allow a finishing charge before switching over to float
mode, as recommended by battery manufacturer in order to ensure that battery gets
fully charged.
Note:- Charger rating shall be arrived at with charger in boost mode and also supplying
100% float load i.e. charger current shall be sum of float & boost rating.
b)
Battery chargers shall automatically select the appropriate mode of operation i.e.
Float or Boost. Means shall be provided to avoid current/voltage surges of harmful
magnitude/nature, which may arise during changeover.
c)
Soft start feature shall be provided to build up the voltage to the set value slowly
within fifteen seconds. The chargers shall have load limiters, which shall cause, when
the voltage control is in automatic mode, a gradual lowering of the output voltage
when the DC load current exceeds the load limiter setting of the Charger. The load
limiter characteristic shall be such that any sustained overload or short circuit in DC
system shall neither damage the Charger nor shall it cause blowing of any of the
charger fuses. The charger shall not trip on overload or external short circuit. After
clearance of fault, the Charger voltage shall build up automatically when working in
automatic mode.
During external short circuit, output of the charger shall be automatically reduced to
near zero volt till it is not isolated/disconnected & normal output voltage shall be
restored by charger circuit on isolation with out any harm to source transformer/
protection/ regulator circuit.
d)
During Float charging, the charger output voltage shall remain within + 1% of the set
value for AC input voltage variation of 230+10%-15% frequency variation of + 5% a
combined voltage and frequency (absolute sum) variation of 10% and continuous DC
load variation from 5% to full load. Uniform and stepless adjustments of voltage
setting shall be provided on the front of the charger panel covering the entire float
charging output range specified. Stepless adjustment of the load limiter setting shall
also be possible from 80% to 100% of the rated output current for float charging
mode.
39
e)
During Boost charging, the Battery chargers shall operate on constant current mode
with maximum current limiter setting (When automatic regulator is in service).
f)
Energising the Charger with fully charged battery connected plus 10% load shall not
result in output voltage greater than 110% of the voltage setting. Time taken to
stabilize, to within the specified limits in clause 3.1 (d) shall be less than five
seconds.
g)
Momentary output voltage of the charger, with the Battery connected shall be within
90% to 110% of the voltage setting during sudden load change from 80% to 20% of
full load or vice-versa. Output voltage shall return to, and remain, within the limits
specified in clause 3.1(d) in less than 1 second after the above mentioned change.
h)
The charger manufacturer may offer an arrangement in which the voltage setting
device for float charging mode is used as output voltage limit setting device for Boost
charging mode, and the load limiter of the float charging mode is also used as Boost
charging current setting device.
i)
Suitable filter circuits shall be provided in all the chargers to limit the ripple content
(peak to peak) in the output voltage to 3% irrespective of the DC load, even when
they are not connected to a battery.
k)
Battery shall be isolated in case of short circuit on the load side.
l)
Battery test circuit shall be provided with suitable resistance for discharging the
battery for 30Sec at 5 hr rate.
m)
All potentiometers shall be electronically locked to contain the various parameters
within allowable limits even if the setting position of potentiometers is changed to
extreme positions.
n)
Minimum Insulation resistance shall be 5 M Ohm.
7.7.2
MCB:
AC MCCB shall be provided at the incomer. DC MCCB with provision of auxiliary
contacts shall be provided at the output of the battery charger.
7.7.3
Rectifier-Transformers and Chokes.
The rectifier transformer and chokes shall be dry and air cooled (AN) type. The rating
of the rectifier transformers and chokes shall correspond to the rating of the
associated rectifier assembly. The rectifier transformers and chokes shall have classB insulation as per IS:4540. Rectifier transformer shall conform to all type tests as
specified in IS:4540/IS: 2026. Type test and routine test reports shall be submitted to
the owner.
7.7.4
Rectifier Assembly:
The rectifier assembly shall be full wave bridge type and designed to meet the duty
as required by the respective charger. The rectifier cells shall be provided with their
own heat dissipation arrangement with natural air cooling. The rectifier shall utilize
diodes/ thyristors with heat sinks rated to carry 130% of the load current continuously
and the temperature of the heat sink shall not be permitted to exceed 850C absolute
duly considering the maximum temperature inside charger panel with ambient
temperature of 500C. The Contractor shall submit calculations to show what
maximum junction temperature will be and what the sink temperature will be when
40
operating at 130% and 100% load current continuously duly considering the
maximum surrounding air temperature for these devices inside the charger panel
assuming ambient temperature of 500C outside the panel. Necessary surge
protection devices and rectifier type fast acting fuses shall be provided in each arm of
the rectifier connections. Static silicon controlled rectifiers and diodes complete with
resistor/capacitor network for surge protection shall be provided.
Design having IGBT or superior technology shall also be acceptable for which full
justification & experience shall be required for acceptance.
7.7.5
Instruments:
Analogue or digital D.C. voltmeter, D.C. ammeter and A.C. voltmeter with 96mm
square display shall be provided for all chargers. The instruments shall be flush
mounted type, dust proof and moisture resistant. The instruments shall have easily
accessible means for zero adjustments. The instruments shall be of 1.5 accuracy
class.
7.7.6
Control and Selector Switches:
Control and selector switches shall be of rotary stayput type of reputed make,
confirming to relevant IS with escutcheon plates showing the functions and positions.
The switches shall be of sturdy construction and suitable for mounting on panel front.
Switches with shrouding of live parts and sealing of contacts against dust ingress
shall be preferred.
7.7.7
Fuses:
Fuses shall be of HRC cartridge fuse link type. Fuses shall be mounted on fuse
carriers, which are mounted on fuse basis. Where ever it is not possible to mount
fuses on fuse carriers, they shall be directly mounted on plug in type bases. In such
cases one insulated fuse pulling handle shall be supplied for each charger. Suitable
fuse fail detector circuits with alarm contacts shall be provided for all D.C. fuses.
7.7.8
Indicating Lamps:
The indicating lamp shall be of panel mounting, LED type and capable of clear status
indication under the normal room illumination. The lamp covers shall be preferably
screwed type, unbreakable and moulded from heat resistant.
7.7.9
Blocking Diode:
Blocking diode, wherever required, with full redundancy shall be provided in the
output circuit of each charger to prevent current flow from the D.C. battery into the
Charger.
7.7.10 Annunciation System:
Visual indications through indicating lamps/ LEDs or annunciation facia shall be
provided in all Chargers for the followings:
i)
ii)
iii)
iv)
v)
vi)
vii)
viii)
ix)
x)
xi)
A.C. supply failure
Rectifier fuse failure
Surge circuit fuse failure
Filter fuse failure.
Load limiter operated
Input AC MCCB trip
Output DC MCCB trip.
Battery on Boost.
Load-side DC under voltage & over voltage alarm.
Battery side DC over voltage alarm.
Earth fault alarm
41
xii)
xiii)
AC available – Battery discharge (Mains available battery discharge) alarm.
Potential free NO contacts shall be provided for following remote alarms:
a)
b)
Battery on boost.
Charger trouble (this being a group alarm initiated by any of the faults other
than Battery on Boost).
7.7.11 Name Plates and Making
The nameplates shall be made of non-rusting metal/3 ply Lamicoid and shall have
black background with white engraved letters and secured by screws. These shall be
provided near top edge on the front as well as on rear side of Charger. Nameplates
with full and clear inscriptions shall also be provided on and inside the panels for
identification of various equipment.
7.7.12 Detailed dimensional drawings, commissioning and operating instructions and Test
Certificates of the manufacturer shall be supplied with the equipment.
7.8
Construction:
7.8.1
The Chargers shall be indoor, floor mounted, self-supporting sheet metal enclosed
cubicle type. The Contractor shall supply all necessary base frames, anchor bolts
and hardware. The Charger shall be fabricated using cold rolled sheet steel not less
than 1.6mm thick. The panel frame shall be fabricated using cold rolled sheet steel of
thickness not less than 2.0mm. Removable un-drilled gland plates of at least 3.0mm
sheet steel and lugs for all cables shall be supplied by the Contractor. The lugs for
cables shall be made of electrolytic copper with tin plating. Cable sizes shall be
advised to the Contractor at a later date for provision of suitable lugs and gland
plates. Ventilating louvers shall be backed with fine brass wire mesh. All doors and
covers shall be fitted with nitrile/neoprene/PU rubber gaskets. The Chargers shall
have hinged double leaf doors provided on front and/ or backside for adequate
access to the Charger internals. All the Charger cubicle doors shall be properly
earthed. The degree of protection of Charger enclosure shall be at least IP-42. The
construction shall meet the requirements of IS: 6619. All equipment mounted in the
cabinet shall be provided with individual labels with equipment designation engraved.
7.8.2
The layout of Charger components shall be such that their losses do not give rise to
excessive temperature within the Charger panel, Location of the electronic modules
will be such that temperature rise, in no case, will exceed 10oC over ambient air
temperature outside the Charger.
7.8.3
Charger panel shall be provided with an illuminating lamp (CFL or tube light) and one
5Amp socket. Switches and fuses shall be provided separately for each of the above.
7.8.4
Locking facilities shall be provided as following:
a)
For locking Float/Boost selector switch in the float position only.
b)
The Charger enclosure door shall have provision for padlocks. Padlock
shackle arrangement shall allow ready insertion of the padlock shackle but
shall not permit excessive movement of the locked parts with the padlock in
position.
7.8.5 Wiring
7.8.5.1 Each Charger shall be furnished completely wired upto power cable lugs and
terminals blocks, ready for external connection. The power wiring shall be carried out
with 1.1kV grade PVC insulated cables conforming to IS: 1554 (Part-I). The control
wiring shall be of 1.1kV grade PVC insulated stranded copper conductors of
42
1.5sq.mm. minimum, conforming to IS:694. Control wiring terminating at electronic
cards shall not be less than 0.75sq. mm. Control terminals shall be suitable for
connecting two wires of 1.5sq.mm stranded copper conductors. All terminals shall be
numbered for ease of connections and identification. At lease 20% spare terminals
shall be provided for circuits on terminal board.
7.8.5.2 Power and control wiring within panels shall be bundled separately. Any terminal or
metal work which remains alive at greater than 415V, when panel door is opened,
shall be fully protected by shrouding.
An air clearance of at least ten (10)mm shall be maintained throughout all circuits,
except low voltage electronic circuits, right upto the terminal lugs. Whenever this
clearance is not available, the live parts should be insulated or shrouded.
7.8.6
Painting:
Pre-treatment & phosphating shall be provided as per IS: 6005. The phosphate
coating shall be ‘class-C’ as specified in IS:6005. Electrostatic powder painting with
final shade – 692 (smoke grey) of IS: 5 shall be provided. The thickness shall not be
less than 50microns.
7.8.7
Packing and Dispatch :
The equipment shall be dispatched securely packed in wooden crates suitable for
handling during transit by rail/road so as to avoid any loss or damage during transit.
7.9
Tests:
Battery chargers including the components shall confirm to all type tests including
heat run test as per relevant Indian Standards. Performance test on the chargers as
per specification shall also be carried out on each charger.
7.9.1
Type Tests:
7.9.1.1 Following type tests, in addition to the requirement of IS: 4540, should have been
carried out on each rating and type of Batter Charger for which reports are to be
submitted.
i)
ii)
iii)
iv)
v)
a)
b)
c)
vi)
Complete physical examination.
Temperature rise test at full load (at highest voltage and highest
current)
Insulation resistance test.
High voltage (power frequency) test on power and control circuits except low
voltage electronic circuits.
Ripple content test at
No load
Half load
Full load
Automatic voltage regulator operation test at specified A.C. supply variations
at:
a)
b)
c)
vii)
viii)
No load
Half load
Full load
Load limiter operation test
Short circuit test at full load and at no load for sustained short circuit of 1
minute minimum shall be carried out.
43
7.10 Technical Requirements of DCDB :DCDB shall conform to relevant Indian Standards. It shall have MCB’s/MCCB’s of
sufficient ratings as per requirements of existing and renovated equipment of all the
four machines. Broadly the DCDB shall feed DC supply to Oil Pressure units,
Lubrication oil system, Protection panels, 22 Kv VCB’s, 440 V ACB’s and emergency
lighting of the power house : Tentative requirements of feeders are given below :S.N.
Description
Current Rating
1
2
3
4
5
6
7
8
9
Lub. Oil System
22 Kv VCB
440V ACB
Protection Panels
LT panels
Unit Control Boards
Emergency Lighting
Spares
Spares
20 A
10A
7A
10A
7A
10 A
7A
20 A
10A/7a
Qty.
4 No.’s
6No.’s
5 No’s
4 No.’s
2No.’s
4 No.’s
3 No.’s
2 No.’s
2 No.’s EACH
Tests :Contractor shall offer the equipment for inspection and testing at works. All tests as per IS
shall be carried out.
44
SECTION-VIII
REPLACEMENT OF PROTECTION PANELS
8.1
Scope
This section of the specification cover the following scope of works: I)
II)
8.2.1
Dismantling/removing of existing four (4) No.’s generator protection panels
and one No. Synchronising trolley all services, labour, tools and tackles
required for dismantling including carriage, stacking at Owner’s store/ yard.
Design, engineering, manufacture, shop assembly & testing before dispatch,
packing and forwarding, transportation, insurance, handling, delivery, storage
at site, erection, testing & commissioning of four (4) No’s. generator
protection panels and one No. Synchronising trolley as detailed in this
specification and handing over to HPSEB LTD. complete with accessories,
equipment, devices, instruments, cabling and wiring etc. including all
services, labour, tools and tackles.
Generator Protection Scheme :The scheme consists for the four generator units.
The electrical protection systems to be provided for the individual generator, shall
comprise of at least following equipment :Four (4) sets of protection equipment for generating units:27G
Generator under voltage relay.
32G
Generator reverse power relay.
46G
Negative Sequence Relay
51V
Voltage restraint over current relay.
51 N
Earth fault relay.
64 S
Rotor Earth Fault Relay
59G
Generator over voltage relay with definite time delay
81G
Over/Under Frequency relay
40G
Loss of field
The protection system shall consist of micro processor based numerical relays for
generator protection and generator transformer protection.
Each trip relay shall be arranged to operate trip coil on the 0.415 kV Air circuit
breaker.
A single line diagram of the main electrical equipment of the power house and its
protection scheme is shown on the drawings No. PHE-01-002.
Means shall be provided to prevent operation of protective equipment due to
magnetising current, in the case of switching-in the transformer from the high voltage
side. Precaution shall also be taken that the unavoidable inductive and capacitive
couplings from the power circuit do not cause disturbances.
45
Protection package shall be facilitated with following:
i)
Man machine communication interface shall be provided with alarm and trip value
setting, displaying of service values, alarm/trip set values, alarmed/ tripped values
etc.
ii)
Self-supervision and indication of any failure.
iii)
Continuous monitoring of external and internal auxiliary voltages.
iv)
Easiness of replacing a module in case of failure.
v)
Communication interfaces or ports.
vi)
Indication of alarm and trip conditions.
8.2.2
Synchronising Trolley
Mobile Synchronising trolley consisting of but not limited to control switches, selector
switches, Check synchronising relay, guard relay, shall be supplied. Synchronising
equipment shall be capable of synchronising any of the generators at 415 V bus
through ACB. Alternatively synchronising panel consisting of above equipment can
also be proposed by the bidder.
8.3
Basic Dimensioning and Ratings
8.3.1
General Arrangement
The system shall provide a high degree of selectivity and discrimination between
faulty and healthy circuits. A microprocessor based modular system associated with
a man machine communication interface shall be offered.
All devices shall remain inoperative during internal faults and transient phenomena.
They shall be insensitive to mechanical shocks, vibration and external magnetic
fields.
The protection systems shall be the standard product of a competent manufacturer,
with organized type test certificates and adequate record of satisfactorily working
plants.
All relays shall be suitable for local reset. They shall have self-monitoring facilities
and LED status indication.
Service voltage failure and any fault in relays and tripping circuitry shall be indicated.
Tripping circuits shall be operable at 70% nominal voltage.
CT's shall be shorted automatically, when relevant modules are withdrawn.
Two trip relays shall be provided to work as main and back trip relays.
The relays shall be provided with the following information, suitably located:
function of relay
phase identification
main characteristics
The protection system shall be divided into protection groups and subgroups, each
installed in a separate cubicle or cubicles. Each protection group shall consist of
solid-state protection relays preferably numerical, auxiliary relays, tripping unit and all
accessories as required and further specified in the following sections.
46
The protection groups are defined as follows:
Mechanical protection for the generating units
Generator protection for the generating unit
Transformer protection, for the main and
station transformers
The protection equipment for the generating unit shall be installed in the Power
house control room or near the UCB if, space is available.
Current transformers, where possible, are to be located so as to include the
associated circuit breaker within the protected zone and shall be located generally as
indicated on schematic drawings.
8.3.2
Relays
Relays shall be approved type with IEC 255 or BRITISH Standard 142 and 5992,
parts 1, 2 and 3 or IS certification, as appropriate, fully tropicalised and shall have
approved characteristics. Only protective relays from well established manufacturers
with a minimum of ten years successful experience in manufacturing protective
relays and with a minimum of five years of field experience shall only be accepted.
The owner will reject any design he considers unsatisfactory or having insufficient
field experience.
The protection relays, shall be located in conventional panels and shall be flush
mounted in dust and moisture proof cases with protection class IP54 and of the draw
out type with rear connections. The protection class of the cover for all relays or
protection systems, in which the modules are mounted shall not be inferior to IP53.
Relays shall be of approved construction and shall be arranged so that adjustments,
testing and replacement can be effected with the minimum of time and labour.
Relays contact shall be suitable for making and breaking the maximum currents,
which they may be required to control in normal service but where contacts of the
protective relays are unable to deal directly with the tripping currents, approved
auxiliary contacts, relays or auxiliary switches shall be provided. In such cases the
number of auxiliary contacts or tripping relays operating in tandem shall be kept to
the minimum in order to achieve fast fault clearance times. Relay contacts shall make
firmly without bounce and the whole of the relay mechanisms shall be as far as
possible unaffected by vibration or external magnetic fields.
Relays, where appropriate, shall be provided with LED or flag indications, phase
colored where applicable. LED or flag indicators shall be of the hand reset pattern
and shall be capable of being reset without opening the case. Where two or more
phase elements are included in one case, separate indicators shall be provided for
each element.
Relays, which rely for their operation, on an external DC supply, shall utilise for this
purpose the same DC supply battery as the trip supply of the associated circuit
breaker trip coils. The supply shall be monitored and an alarm provided in the event
of failure.
All DC breakers and relays for DC main switchgear protection shall be based on AC
operated trip and close coils and protection relays.
47
Any auxiliary supplies needed shall be drawn from the DC Distribution Board and not
from the separate internal batteries in the protection equipment.
Relays, whether mounted in panels or not, shall be provided with clearly inscribed
labels describing their functions and designation in addition to the general-purpose
labels.
To minimise the effect of electrolysis, relay coil operating on DC shall be so
connected that the coils are not continuously energised from the positive pole of the
battery.
Draw out type relay shall be so designed that when the relay is drawn out ,
associated CT's shall be automatically short-circuited and tripping circuits
disconnected.
All static relays shall be adequately protected against damages from incoming surge
and shall meet relevant IEC, BS, IS and ANSI SWC test standards.
The input circuit must be galvanically isolated from the electronic circuits. Potential
free output contacts must be suitable for the direct control of breaker trip coil.
The setting ranges of the protection devices and the performance of the CT's and
VT's shall fit the requirements of the individual circuits. Time delayed modules shall
have definite time characteristic with continuous adjusting range. The selectivity with
the other protection modules shall be proved by a protection setting study covering
the entire system. This study shall be based on a short circuit calculation for
maximum and minimum short circuit capacity and shall prove the selectivity of the
relay setting from the high voltage to the low voltage system, taking into
consideration the different modes of operation of the system. This study shall also
prove correct matching with the provided instrument transformers.
Trip circuit supervision relays shall be provided to monitor each circuit of 415 V air
circuit breakers and earth relay shall have sufficient contacts for visual/audible alarm
and indication purposes.
The trip circuit supervision scheme shall provide continuous supervision of the trip
coil and trip circuits with the circuit breaker in either the open or close position.
Relay elements shall be delayed on drop off to prevent false alarms during faults on
dc wiring on adjacent circuits or due to operation of a trip relay contact.
Series resistance shall be provided in trip circuit supervision circuits to prevent maltripping of a circuit breaker if a relay element is short-circuited.
Breaker failure protection shall be fitted to all air circuit breakers.
The breaker failure protection on a circuit breaker shall be initiated by all the other
protection devices, which normally initiated tripping of that breaker. In the event of
the circuit breaker failing to open within a pre selected time, the breaker failure
protection shall initiate tripping of all adjacent circuit breakers connected to the same
bus bar, transfer tripping of the line breakers.
The relays shall have an operating times of 10 ms, and a consistent reset time of less
than 15 ms. The relays shall be more sensitive than the most sensitive circuit
protection, both phase and earth fault. The relays shall be capable of remaining in
48
the operated position continuously and of carrying twice the circuit rated current
continuously.
The operating time of the breaker failure protection shall be selected by means of
timers with ranges of 50 to 500 ms. There shall be two timers per circuit breaker. The
timer tripping outputs shall be connected in a two out of two basis and shall energize
both tripping coils of the adjacent circuit breakers via two back tripping circuit from
separate dc supplies. The timers shall be of static design to minimise over travel.
8.3.3
Auxiliary Relays
Auxiliary relays for inputs from the protection sensors and devices such as thermal
relays, pressure switches etc. shall be provided as specified in the following sections
and as necessary for the installation.
The relays shall be equipped with a manually reset flag indicator when applicable.
Each relay shall have self-resetting potential free contacts of suitable rating as
needed for connection in the tripping circuits and at least two self-resetting potential
free contacts for local and remote alarm and supervision, both wired to terminals.
All relays shall be clearly marked with the corresponding relay function.
The tripping relays shall have contact ratings suitable for acting directly on the trip
coils and solenoids of the respective circuit breakers and shut down devices.
As an alternative a tripping matrix having provisions for easy selection of the tripping
scheme, and having means for manual and automatic testing of the trip circuits, can
be offered.
8.3.4
Control and Tripping Circuitry
The tripping circuits shall be accomplished via a tripping MATRIX.
The MATRIX shall include all electrical and mechanical signals as per alarm/tripping
schedule and sequence diagram.
Any fault in tripping circuit shall be annunciated individually.
Buzzer and bell shall be provided for alarm and trip functions separately.
Each relay or relay assembly shall have a test device which facilitate checking the
correct functioning of the equipment during operation or stand still.
The trip circuits shall not be interrupted during test procedure. LED’s shall indicate
correct working.
For relay testing and setting by means of a portable, precision test set all required
circuits shall be terminated to test plugs/switches, arranged at easily accessible
locations.
8.3.5
Power Supply Requirements
The 110V dc shall be provided for the power supply to the control and protection of
ac switchgear equipment, while ac shall be provided for the power supply to the
49
control and protection of dc switchgear. Both systems shall be used to supply
auxiliary voltage and tripping voltages to the protection system.
All components of the protection system shall function properly at dc voltage from
70% - 115% of nominal voltage.
If short-circuit protection is needed inside each protection group, miniature circuit
breakers shall be used, having auxiliary contacts for initiating alarm for open position.
Converters and suppression filters shall be provided for each protection part.
The 110V battery banks installed in the battery room shall feed the protection
systems. Relay shall be suitable for operation on 110V DC systems without the use
of voltage dropping resistors.
8.4
Performance Criteria and Requirements
The protection system shall be capable of performing all intended duties and it is the
responsibility of the contractor to supply the equipment as per guaranteed technical
particulars.
8.5
Design and Construction
The protection system shall be the standard product of a competent manufacturer,
with organized type test certificates and adequate record of satisfactorily working
plants.
The protection system offered by contractor shall be suitable and approved type for
hydro power projects. The relay used in protection system shall be of the numerical,
and plug in type arranged in protection cubicles. All relays including all ancillary
devices, such as interposing transformers, tripping matrix and relays, test facilities,
power supply units, etc. with all circuits complying to IEC 60255-4 Recommendation.
8.6
Indicating and Recording Instruments
8.6.1 Indicating instruments shall be as per single line diagram depicted in Drawing
No.PHE-02-001 of Vol. 2C . All instruments shall be flush mounted on the top of the
cubicle in a separate compartment. The instrument case shall be dust proof, water
tight, vermin proof and especially constructed to adequately protect the instrument
against damage or deterioration due to high ambient temperature and humidity. The
instrument shall be provided with all auxiliary appliances and any special tools
required for their maintenance.
8.6.2
All instruments shall be designed for accurate measurement of the quantity or state
under all conditions of operation and any error due to change in ambient condition
shall be kept to minimum. The instrument shall be damped to comply with the
requirement of clause 7.2 of IS 1248 (Part-I) or equivalent. All the instruments shall
comply with the requirement of first grade instrument of switch board type as per
IS:1248 or equivalent standard. All instruments and meters shall be accurately,
adjustabled and calibrated before shipment and shall have means for calibration,
checking and adjustment at site.
8.6.3
The metric unit shall be used for displaying the values. The instrument shall be
capable of withstanding over loads applied in accordance with IS:1248 or equivalent.
The instrument shall be capable of withstanding the following tests, viz effect of
shock, vibration and effect of humidity.
50
8.7
Calculation requirements
The contractor is required to submit time setting for different relays and selection of
relay types to owner for approval. The contractor is required to submit the DC power
requirements. Contractor shall also submit a drawing of complete protection scheme.
8.8
Shop Tests
8.8.1
Type Tests
All standard components of the protection systems shall have passed appropriate
type tests in accordance with the relevant standards. The contractor is required to
submit type test certificates to the owner.
8.8.2
Routine Tests
These tests shall include material and tests during manufacture as per the
manufacturer's practice. The contractor is required to submit complete routine test
reports. The following inspections and tests shall be performed on the completely
assembled protection systems:
8.9

Visual inspection

Wiring test

Insulation test

High voltage test on outgoing circuits

Functional test
Field Tests
The contractor shall prepare a detailed test program based on the requirements of
the applicable standards and the specifications.
All test results shall be recorded including the details on the used test equipment and
instruments.
51
SECTION-IX
REPLACEMENT OF 24 KV SWITCHGEAR
9.1
Scope: This section of the specification cover the following scope of works: I) Dismantling/removing of existing oil circuit breakers and associated control and
protection panels all services, labour, tools and tackles required for dismantling
including carriage, stacking at Owner’s store/ yard.
II) Design, engineering, manufacture, shop assembly & testing before dispatch,
packing and forwarding, transportation, insurance, handling, delivery, storage at site,
erection, testing & commissioning of indoor type 630 A, 24 kv indoor type vacuum
circuit breakers (draw out type) control & Relay panel complete with protective
relays for two (2) transformers and four (4) feeders as detailed in this specification
and handing over to HPSEB LTD. complete with accessories, equipment, devices,
instruments, cabling and wiring etc. including all services, labour, tools and tackles.
9.2
9.2.1
Standards
The equipment including all accessories supplied under this Contract shall conform
to relevant IEC or IS or British Standards and shall be in accordance with the latest
edition or revision thereof.
9.2.2
9.2.3
Equipment/material conforming to any other recognized standard, which ensures
an equal or better quality other than, the provision of this specification, would also
be acceptable. Where the equipment offered, conforms to any other standard, the
salient points of difference between the standards adopted and the provision of this
specification shall be clearly brought out in the bid.
A complete list of the adopted Standards shall be supplied alongwith the bid.
9.3
Workmanship and Design
The material and workmanship throughout shall be the best of their respective kind.
The design shall be such that installation, replacement and general maintenance
may be under taken with the minimum of dismantling time and expense. No
patching, plugging or other such means covering defects, discrepancies or cover
shall be carried out with out the prior permission of the Purchaser.
9.4
General Rating of Equipment
The required capabilities and rating of the 24 kV switchgear will be governed by the
requirement given below: i)
Nominal system voltage
22kV
ii)
Highest System voltage
24kV
iii)
One min. power frequency withstands voltage.
50kV (rms)
iv)
Impulse withstand voltage positive and negative
v)
polarity.
95Kv (peak)
System frequency
50Hz
52
vi)
No. of phases
Three
vii)
Rated normal current
630 A
viii)
Rated breaking capacity
6.3 kA
ix)
Rated making capacity
15.75kA
x)
Rated operating duty cycle
0-3min.-CO-3
min.-CO
xi)
9.5
Total break time for any current upto the
Rated breaking current.
Less than 4 cycles.
xii)
Control circuit voltage.
110V DC+ 10% variation.
xiii)
Auxiliary A.C. supply
1 phase,240 V,50 Hz
Type and Details
24kV indoor switchgear shall be steel enclosed indoor type. This shall be
suitable for continuous operations and shall comply with the requirement of
latest addition of relevant IEC, BS or Indian Standard. Each switchgear shall
be complete with vacuum circuit breaker mounted on draw out trolley, bus
bars, instrument transformers, instruments, protective relays, cable boxes and
glands with all necessary wiring and auxiliary devices required to perform its
functions. All the instruments, control switches indicating devices and relays,
should be mounted on the front panel as a separate compartment. The
design and arrangement of the equipment shall be such that adequate space
and access is provided for inspection and maintenance of wiring, terminals
switches, cables and end boxes etc. The switchgear shall be vermin proof
and dust tight. Bus bars, CT & cable compartment & breaker compartment
shall be provided with independently operated automatic shutters to avoid
accidental contact with live parts. The arrangement of bus bars shall be such
so as to provide ready extension for additional unit on either side.
9.6
24 KV Circuit Breakers
9.6.1
The electrical rating of the circuit breaker shall be as per clause 9.4 of this
section. The breaker offered shall be vacuum type conforming to all the
requirements of IEC/BS or Indian Standard.
The breaker compartment shall be designed to have fully draw-out self
contained truck arrangement with breaker mounted on the same. The devices
fitted on the breaker truck shall allow for easy insertions and withdrawal of
breaker from service position. The breaker truck shall have the following two
definite positions.
i)
Service position: - In this position the circuit contacts as well as
secondary contacts and fixed secondary contacts should get engaged
on to the fixed power contacts and fixed secondary contacts
respectively.
ii)
Test position: - In this position power contacts of the mobile portion of
circuit breaker shall remain isolated from the fixed position whereas
53
secondary contacts shall remain connected to the fixed secondary
contacts.
The circuit breaker mobile truck shall be provided with additional metal barrier
i.e. front shield between the actual breaker housing and the front door. Front
door of the cubicle shall be provided with padlocking facilities. The front door
should be closed and pad-locked even when the breaker is in test position
Safety interlocks and automatic shutter shall be provided to ensure the
following:a)
The circuit breaker cannot be inserted into the service position when
in closed position.
b)
The circuit breaker cannot be withdrawn from the service position
unless it is in open position.
c)
Access to the breaker chamber and circuit breaker shall not be
possible unless the breaker is withdrawn.
9.6.2
The circuit breaker shall be provided with rapid and smooth interruption of
currents under all conditions completely suppressing all undesirable
phenomena on even under the most severe and persistent short circuit
conditions or when interrupting small leading and lagging currents. The detail
of any device or special feature incorporated to limit or control the rate of rise
of re-striking voltage across the circuit breaker contact shall be stated. The
over voltage caused by the circuit breaker switching on inductive and
capacitive loads shall not exceed 2.5 times the normal phase to neutral
voltage. The total break time for the circuit breaker throughout the range of its
operation duty shall be stated in the bid and it shall be guaranteed.
9.6.3
The circuit breaker shall be provided with suitable operating mechanism with
automatic recharging of spring with the help of geared motor. Provision shall
also exist for one detachable handle for manual charging in the event of
failure of auxiliary voltage. The switchgear shall be suitable for remote
operations in addition to auxiliary local operating mechanism. The operating
mechanism shall be trip-free. All working parts in the mechanism shall be of
corrosion resistant material and all bearings, which require greasing, shall be
equipped with pressure grease fitting. The mechanism, shall be strong, quick
in action with minimum noise and shall be removable without disturbing the
other parts of the circuit breaker. The operating mechanism alongwith its
accessories shall be housed in a weatherproof cabinet with hinged doors
installed just adjacent to the breakers. The circuit breaker shall also be
provided with means for manual operation for maintenance purpose and local
tripping and closing. A local/remote change over switch shall also be
provided. Operating mechanism shall also be provided with operation counter
and space heaters with suitable thermostat switch to avoid condensation.
9.6.4
The control circuit shall be designed to operate on 110 V.D.C. supply with a
variation from 70% to 110% of rated voltage. A.C power supply for auxiliaries
shall be available at 240 V, single phase, 50 c/s. Provision shall be made for
locking the breaker mechanism in open position and locking the doors in
closed position through pad locks. Lamp indication as well as mechanical
“open” and “close” indication shall be provided on the switchgear panels to
show the contact positions of circuit breakers. Twelve numbers of the
secondary auxiliary contacts shall be provided on mobile portion of circuit
breaker in any combination of NO and NC and completely wired up to
terminal blocks.
54
9.6.5
Means shall be provided for easy access to the contacts and other parts of
the switchgear for inspection and repairs. When these facilities are obtained
by provision of manholes, the manhole shall be of adequate dimensions and
hinged type and located in convenient place.
9.7
Bus Bars
All the bus bars within the switchgear assembly shall be air insulated and
shall be housed in a separate compartment of the switchgear assembly
supported on insulated supports. It shall have rated current capacity of not
less than the rated capacity of the circuit breaker. Bus bar shall also have
mechanical and thermal capacity not less than that represented by the short
time current rating of the circuit breaker. The bus bar shall be of aluminum
conforming to relevant IEC, BS or Indian standard. Phase-to-earth and
Phase-to-Phase clearances shall also be in accordance with IEC standards
and corrections in the clearance on account of altitude correction factor shall
also be incorporated. No insulation sleeves shall be provided on the bus bars
to reduce the phase-to-earth and phase-to-phase clearances. Support
insulators shall be strong enough to take up dynamic forces on account of
short circuit. Temperature rise of the bus bars and joints shall also be as per
IEC standard. The bus bar phases shall be identified by painted bands of red,
yellow, & blue spaced at suitable distances.
9.8
Current Transformers
9.8.1
Current transformers shall be mounted with in the cubicle and shall comply
with the requirements of IS: 2705-1992 and its latest amendment. Current
Transformers as shown in drawings No. PHE-01-002 of Vol. 2C shall be
supplied by the contractor. The technical particulars shall be as given below: i)
Normal service voltage
22kV.
iii)
Power frequency withstand voltage
50 kV
iv)
Impulse withstand voltage
95 kV Peak.
v)
Highest system voltage
24kV.
Necessary steel brackets for mounting these CTs inside the cubicle shall also
be provided. The required CT ratio, burden and accuracy class shall be as
mentioned in the schedule of requirement. The Bidders shall have the option
of offering multicore C.T.’s of accuracy classes specified in place of single
core C.T’s inside the panel. The Bidder shall also furnish the knee point
voltages, magnetizing currents and secondary winding resistances of P.S.
class C.T’s. However, actual requirement will have to be worked out in coordination with other concerned suppliers and bidder should agree to
accommodate any change in requirement with regards to numbers and
characteristics of CT’s at the stage of approval of drawings. In addition to
above technical particulars, the CT’s shall have the following ratings also.
a)
Continuous current rating factor for secondary winding.
b)
Thermal short time rating one second with secondary short circuit,
winding temperature shall not exceed the limit as per IEC 185.
c)
Frequency: - 50HZ
55
9.8.2
The secondary winding of the CT’s shall be fully distributed around the core at
all nominal taps. The actual exciting current up to the knee point voltage shall
not vary beyond the permissible standard from the normal exciting current.
9.8.3
All the routine tests, type tests and tests at site shall be carried out on current
transformers in accordance with Indian standard with up to date amendments
thereof. The tests to be carried out by the Contractor shall clearly be stated in
the bid.
9.8.4
Other requirement of different 22 kV rating CT’s are given below: S.N.
DESIGNATION
RATIO
PURPOSE
BURDEN
1
CT-6
50/1A
Directional O/C 50
&
E/F
Protection
5P10
2
CT-7 (CORE-I)
50/1 A
O/C
&
Protection
5P10
(CORE-II)
50/1A
Metering
E/F 50
50
ACCURACY
CLASS
0.5
9.9
Voltage Transformers
9.9.1
Voltage transformer shall confirm to IS: 3156-1992 and its latest
amendments. Voltage transformer shall be provided as shown in drawings
No. PHE-01-002 of Vol. 2C and be of magnetic type. The voltage transformer
shall be single-phase type and shall be mounted inside the cubicle. Voltage
transformer shall be complete with its own high and low tension fuses and
current limiting resistances if required. The fuses shall be so arranged that
they are readily accessible and easily/quickly replaceable. The burdens of
PT’s are given in cl.9.9.2 and are tentative only. The Bidder shall indicate in
his offer the actual burden imposed by relays, meters so that modification, if
required, in the rated burden of transformer can be done at the time of placing
of order. The technical particulars shall be as given below: i)
Normal service voltage
22kV.
iii)
Power frequency withstand voltage
50 kV
iv)
Impulse withstand voltage
95 kV Peak.
v)
Highest system voltage
24kV.
All the routine tests, type tests and tests after installation given in relevant
Indian Standard shall be carried and Bidders shall give details of such tests
which shall be carried out, with their offer.
9.9.2
Other requirement of Voltage transformer are given below: -
Sr.No.
DESIGNATION RATIO
BURDEN
1
CORE-I
50 VA
22KV/3/110V/3
56
ACCURACY
CLASS
3P
CORE-II
22KV/3/110V/3
50 VA
CORE-III
22KV/3/110V
50 VA
0.5
3P
9.10
Indicating Instruments
9.10.1
Indicating instruments for measurement of electrical parameters of outgoing
feeders shall be as per single line diagram depicted in drawing No Drawing
No.PHE-02-001 of Vol. 2C.
All instruments shall be flush mounted on the top of the cubicle in a separate
compartment. The instrument case shall be dust proof, water tight, vermin
proof and especially constructed to adequately protect the instrument against
damage or deterioration due to high ambient temperature and humidity. The
instrument shall be provided with all auxiliary appliances and any special tools
required for their maintenance.
9.10.2
9.10.3
9.11
All instruments shall be designed for accurate measurement of the quantity or
state under all conditions of operation and any error due to change in ambient
condition shall be kept to minimum. The instrument shall be damped to
comply with the requirement of clause 10.5 of IS 1248 or equivalent. All the
instruments shall comply with the requirement of first grade instrument of
switch board type vide IS:1248 or equivalent standard. All instruments and
meters shall be accurately, adjustable and calibrated before shipment and
shall have means for calibration, check and adjustment at site.
The metric unit shall be used for displaying the values. The instrument shall
be capable of withstanding over loads applied in accordance with IS:1248 or
equivalent. The instrument shall be capable withstanding the following tests,
viz effect of shock, vibration and effect of humidity.
Relays
The electrical protection systems to be provided, shall comprise of at least of
the following equipment :-
9.11.1
Transformer Protection :Four (4) sets of protection equipment for generating units:51T
50
67 & 67 N
Over current relay (LT Side).
Local Breaker Back Up (HT Side).
Directional over current and earth fault relay (HT Side).
The protection system shall consist of micro processor based numerical
relays for generator transformer protection.
The transformer overall protection shall be provided for the detection of phase
and earth faults .
Group-A
Winding temperature trip.
Buchholz main tank.
Group - B
Oil temperature trip.
57
9.11.2
Transmission Line Protection :-
9.11.2.1
The electrical protection systems to be provided for the four (4) no.’s line
feeder, shall comprise of at least of the following equipment :Four (4) sets of protection equipment for feeders :50
51 & 51 N
Local Breaker Back Up
Over current and earth fault relay
Each trip relay shall be arranged to operate onto both trip coils of the 22 kV
vacuum circuit breaker
9.11.2.2
The relays shall be provided as per single line diagram depicted in drawing
No PHE-02-001 , Vol. 2C Relays shall be of Numerical type only. Relays
shall be Alstom/ABB/ Siemens make. All the relays shall be suitable for
operation over the range -70% to 110% of the nominal D.C. voltage. The
relays shall be designed to have the minimum possible quiescent drain on the
batteries.
9.11.2.3
The relay should be designed to secure against mal-operation for D.C.
voltage dips, switch on, switch off and intermittent interruption of the power
supply. All the relays shall have different contacts for alarm and tripping. All
the relays should conform to the National & International Standards with up
to date amendments.
9.12
Lightning Arrestors
9.12.1
The lightning arrestor shall be of distribution class with non linear resistance
arrestor and shall be mounted in the cubicle. The lightning arrestor should
conform to IS:3070/IEC-994 except where specified otherwise. Lightning
arrestors manufactured to any other standard which ensures an equal or
better quality than IS 3070 shall be also acceptable. Where the equipment
conforms to any other standards other than IS: 3070-difference between the
standard shall be clearly brought out.
9.12.2
The lightning arrestors shall be designed according to the latest techniques,
testing and development incorporating the design features such as low
resistance, non linear resistor, magnetically blown out spark gaps, voltage
grading resistors and capacitor pressure relief device etc.
9.13
Panels
All enclosures and Panels/Cubicles shall be of good quality Standard
production. Panels/cubicles shall be free floor standing type of rigid frame
covered with removal steel sheets. The frame should be bolted to floor. There
shall be provision and enough space for entrance of cables from below. The
cubicles shall be ventilated if needed, in this case removal filter inserts shall
be fitted to the air entrance openings. Provision for cable fastenings shall be
made inside the cubicles and enclosures and sufficient space for cable
fastenings to nearest terminals shall be kept. All control and indicating
instruments such as contactors, circuit breakers, auxiliary relays, indicating
instruments, switches etc. shall be functionally displayed in appropriate
locations. The layout is subject to approval of the Engineer –in- charge,
58
however, standard layout of the manufacturer is acceptable with minor
changes if required. The panels/cubicles should be of IP-20 protection class
and the outside paint shall be powder coated, pebble gray (RAL 7032) and
inside either pebble gray or enameled white. No other shade shall be
accepted.
9.14
Earthing Arrangement
Two separate copper earth buses of suitable cross-sectional areas shall be
provided in the 24 kV switchgear designed for a short circuit current of 25 kA.
One earth bus shall run along the entire rear length of the switchgear panels
and the lightning arrestors shall be connected to this earth bus. The other
earth bus shall be run along the entire front side of the switchgear panel and
the earth connections from the relays and control devices shall be made to
this bus. Both the earth buses shall be connected to the station M.S. earth
bus at the extreme ends using bi-metallic joints. The earthing inside the
panels shall be done using green coloured PVC flexible copper cables.
9.15
Terminal Blocks
(i)
All terminal blocks shall be mounted in an accessible position with the
spacing between adjacent blocks not less than 100mm and the space
between the bottom blocks and the cable gland plate being a
minimum of 200mm. Sufficient terminal shall be provided to allow for
the connection of all incoming and outgoing cables including spare
conductors and drain wires. In enclosed cubicles, the terminal blocks
shall be inclined towards the door for facilitating terminations. At least
10% spare terminal shall be provided.
(ii)
The terminals shall be of the channel mounting type and shall
comprise a system of individual terminals so that terminal blocks can
be formed for easy and convenient cabling consistent with the high
reliability required of the circuits.
(iii)
The terminal blocks shall be provided with shorting links and
paralleling links where applicable, and mounted identification numbers
and/or letters.
(iv)
The terminal blocks shall conform to the applicable NEMA standard.
The smallest size to be used shall be designated for 2.5 millimeter
square wire and no more than two (2) conductors shall be connected
under one terminal clamp.
(v)
Terminal identification shall be provided corresponding to wire number
of connected leads.
(vi)
Power circuit terminals shall be segregated from other terminals and
shall be equipped with non-inflammable, transparent covers, to
prevent contact with live parts. Warning labels with red lettering shall
be mounted thereon in a conspicuous position.
(vii)
Disconnecting type terminals shall be provided for the Current &
Voltage connections and non-disconnecting type used for other
control circuits.
(viii)
One common alarm annunciator shall be provided in one of the VCB
panels to annunciate the trip and non trip alarms. The annunciator
shall have automatic silencing facility i.e. the audio alarm shall silence
59
off after one minute if the same is not acknowledged. However the
alarm window shall remain lighted till the same is reset or the fault
cleared.
9.16
Mandatory Spares : Following Mandatory spares shall be supplied :1
2
3
4
Closing Coil
Trip Coil
TNC Switch
Overcurrent Relay
2 No.
2 No
2 No.
1 No.
9.17
Erection and Commissioning at Site : -
9.17.1
The Contractor shall furnish all labour, tools, tackles, slings and support and
all other provisions or materials necessary to assemble, erect, install, test and
commission the 24kV VCB’s in a thorough workmanlike manner following the
best modern practices. The VCB’s and all their components shall be placed
with great care and shall be aligned correctly.
9.17.2
The panels/cubicles shall be provided with complete set of foundation holding
down bolts, washers, nuts, plates and other fixtures as may be required and
these shall be supplied by the Contractor.
9.17.3
All test equipments and instruments shall be provided by the Contractor free
of charge and shall remain the Contractor’s properties after the fulfillment of
the field tests.
9.17.4
All civil works required for foundation shall be carried out by the Owner or his
representative. The Contractor is required to submit the foundation drawings
and supporting steel well in time.
9.18
Tests
9.18.1
Type test certificates, to ensure the quality and capability of the offered
equipment, must accompany the bid documents. The Bidder shall specify the
details of measurement and conducting of these tests alongwith the bid.
TYPE TEST shall only be carried out on switchgear only if manufacturer
has not conducted on the similiar equipment. However manufacturer
has to submit the type test reports.
9.18.2
All the tests to be carried out on all the equipment shall conform to IEC, BS
and Indian Standard. Bids not accompanied with the relevant type test
certificate confirming to IEC & IS shall be summarily rejected. Routine tests
shall be carried out on each equipment in the presence of Owner’s
representative at the manufacturer’s expenses at his works.
9.18.3
Circuit Breakers
TYPE TEST
1.
Short circuit tests comprising of: -
a)
Breaking capacity tests for recovery voltage, the symmetrical and
asymmetrical breaking currents, amplitude factor and rate of rise of
recovery voltage.
b)
Making capacity tests for applied voltage and making current.
60
c)
Test duty.
d)
Short time current tests.
2.
a)
Temperature rise test of the main circuit.
b)
Temperature rise test of the auxiliary circuit.
c)
Measurement of the resistance of the main circuit
3
Operational tests.
4
Mechanical endurance tests
5
a)
Impulse voltage withstand test.
b)
One minute power frequency withstand voltage test.
ROUTINE TEST: -
9.18.4
1
Operation test.
2
Measurement of the resistance of the main circuit.
3
One minute power frequency voltage withstand test.
Potential Transformer : TYPE TEST
1.
Verification of terminal marking and polarity.
2.
Induced Power frequency test on primary winding
3
Induced Power frequency test on secondary winding.
4.
Determination of errors according to the requirement of the
appropriate accuracy.
5.
Temperature rise test.
6.
Impulse voltage test.
ROUTINE TEST: -
9.18.5
1
Verification of terminal marking and polarity.
2.
Induced Power frequency test on primary winding
3
Induced Power frequency test on secondary winding.
4.
Determination of errors according to the requirement of the
appropriate accuracy.
Current Transformer :TYPE TEST
1
Verification of terminal marking and polarity.
2.
High voltage power frequency on primary winding
3
High voltage power frequency test on secondary winding
4.
Over voltage interturn test
5.
Determination of errors according to the appropriate accuracy class.
6.
Short time current test.
7.
Temperature rise test.
61
8.
Impulse voltage test.
ROUTINE TEST: 1.
Verification of terminal marking and polarity.
2.
High voltage power frequency on primary winding
3
High voltage power frequency test on secondary winding
4.
Over voltage interturn test
5.
Determination of errors according to the appropriate accuracy class.
ADDITIONAL TESTS FOR MEASURING CT’s: TYPE TEST: i)
Accuracy test
ii)
Instrument security current test.
ROUTINE TEST: Accuracy test:
a)
For class 5P10
Type and Routine tests: -
9.18.6
i)
Current error and phase displacement test.
ii)
Composite error test.
Lightening Arrestors :TYPE TEST: 1
Voltage withstand test of arrestor, insulation.
2.
Power frequency spark over test.
3
100% 1.2/50 micro second spark over test.
4.
Front of wave impulse spark over test.
5.
Residual voltage test.
6.
Impulse current withstand test.
7.
Operating duty test.
8.
Temperature cycle test on porcelain housing.
9.
Porosity test on porcelain housing.
10.
Galvanizing test on metal parts.
ROUTINE TEST: -
9.18.7
1
Power frequency voltage spark over test.
2.
Visual examination test on porcelain housing.
Site Tests : All the equipments supplied shall be tested at site after successful installation
as per the recommendation of IEC or equivalent Indian Standard. Details of
the test and standard according to which these tests shall be carried out
should accompany the bid. Any other test specifically required to prove the
successful installation of the equipment shall also be carried out. The
Contractor shall indicate details of tools plants and instruments required for
site testing.
62
SECTION-X
REPLACEMENT OF 415 V SWITCHGEAR
10.1
Scope:This section of the specification cover the following scope of works: i)
ii)
10.2
Dismantling/removing of existing Air Circuit Breakers (ACB’s), all services,
labour, tools and tackles required for dismantling including carriage, stacking
at Owner’s store/ yard.
Design, engineering, manufacture, shop assembly & testing before dispatch,
packing and forwarding, transportation, insurance, handling, delivery, storage
at site, erection, testing & commissioning of five No. 1000 A and 3 No’s.
2000A , 415V indoor type air circuit breakers (draw out type) panel, as
detailed in this specification and handing over to HPSEB LTD. complete with
accessories, equipment, devices, & fitting, instruments, cabling and wiring
etc. including all services, labour, tools and tackles.
Type and Rating of 415 Volt Switchgear :-
10.2.1 The 415 volts air circuit breakers shall have the following ratings :A
i)
ii)
iii)
iv)
v)
vi)
vii)
viii)
B
i)
ii)
iii)
iv)
v)
vi)
vii)
viii)
C
i)
ii)
iii)
iv)
v)
vi)
vii)
viii)
Unit Breakers (4 No.’s) :No. of poles
3
Service voltage
415 V.
Normal current
1000
Frequency
50 Hz.
Symmetrical breaking capacity
10 KA
Short circuit making capacity
25 KA
Short time current
10 KA
Control circuit voltage
110 Volts D.C.
Transformer Breakers and Bus Couplers(3 No.’s) :No. of poles
3
Service voltage
415 V.
Normal current
2000
Frequency
50 Hz.
Symmetrical breaking capacity
20 KA
Short circuit making capacity
50 KA
Short time current
20 KA
Control circuit voltage
110 Volts D.C.
DG Breakers ( 1 No.’s):No. of poles
3
Service voltage
415 V.
Normal current
1000
Frequency
50 Hz.
Symmetrical breaking capacity
10 KA
Short circuit making capacity
25 KA
Short time current
10 KA
Control circuit voltage
110 Volts D.C
63
10.2.2 Special Requirements :Circuit breakers for DG incomer and Bus coupler shall be provided with inbuilt
overcurrent and earth fault protection. LT Distribution Board shall be
connected with 415 V Bus through cable. A separate Chamber shall be
provided for cable connection for this purpose.
10.3
Standards :The circuit breaker shall comply in all respect with the requirement of latest issue of
Indian Standard No. 13947. Short circuit performance category P-2 except where
specified otherwise. Equipment meeting with any other authoritative standard which
ensures equal or better quality than the standard mentioned above is also
acceptable. Where the equipment offered conform to any other standard, the salient
features and points of difference between the standard adopted and the Indian
Standard shall be clearly brought out in the tender.
The L.T. switchgear shall comply in all respects with the latest editions of the
following Indian Standards:I.S. 13947, 2516
Specifications for Alternating current circuit breakers.
I.S. 8623
Specification for factory built assemblies of switchgear
and control gear ; Voltages up to and including 1000 V
A.C and 1200 V. D.C.
I.S. 4237
General requirement for switchgear and control gear for
voltages not exceeding 1000 volts
I.S. 2147
Degree of protection provided by enclosures for L.V.
Switchgear and Control gear.
I.S. 2705
Specification for current transformers.
I.S. 3156
Specification for voltage transformers.
I.S. 3231
Specification for electrical relays.
One number authorized copy of all the applicable standards (IS or IEC) shall be
supplied after the award of work.
10.4
Particulars of 415 V System :The single line diagram for 415 V system is depicted in Drawing No.PHE-02-001 of
Vol. 2C
10.5
Switchboards and Control Boards:The A.C switchgear shall consist of following switch boards :-
S.N.
DESCRIPTION
QTY.
CURRENT RATING
i)
ii)
iii)
iv)
Incoming generators
DG set incomer
Outgoing transformers
Bus Coupler
4
1
2
1
1000A
1000A
2000A
2000A
No.’s
No.and
No.’s
No.
Other technical requirements are listed under clause 10.2.1 of this section.
10.6
Type and Details
415 V indoor switchgear shall be steel enclosed indoor type. This shall be suitable for
continuous operations and shall comply with the requirement of latest edition of
64
relevant IEC, BS or Indian Standard. Each switchgear shall be complete with air
circuit breaker mounted on draw out trolley, bus bars, instrument transformers, all
necessary wiring and auxiliary devices required to perform its functions. All the
instruments, control switches indicating devices and relays, should be mounted on
the front panel as a separate compartment. The design and arrangement of the
equipment shall be such that adequate space and access is provided for inspection
and maintenance of wiring, terminals,switches, cables and end boxes etc. The
switchgear shall be vermin proof and dust tight. Bus bars, CT & cable compartment
breaker compartment shall be provided with independently operated automatic
shutters to avoid accidental contact with live parts. The arrangement of bus bars shall
be such so as to provide ready extension for additional unit on either side.
10.7
415 V Circuit Breakers
The electrical rating of the circuit breaker shall be as per clause 10.2 of this section.
The breaker offered shall be air break type conforming to all the requirements of
IEC/BS or Indian Standard.
The breaker compartment shall be designed to have fully draw-out self
contained truck arrangement with breaker mounted on the same. The devices fitted
on the breaker truck shall allow for easy insertions and withdrawal of breaker from
service position. The breaker truck shall have the following two definite positions.
i)
Service position: - In this position the circuit contacts as well as secondary contacts
and fixed secondary contacts should get engaged on to the fixed power contacts and
fixed secondary contacts respectively.
ii)
Test position: - In this position power contacts of the mobile portion of circuit breaker
shall remain isolated from the fixed position whereas secondary contacts shall
remain connected to the fixed secondary contacts.
The circuit breaker mobile truck shall be provided with additional metal barrier
i.e. front shield between the actual breaker housing and the front door. Front door of
the cubicle shall be provided with padlocking facilities. The front door should be
closed and pad-locked even when the breaker is in test position Safety interlocks and
automatic shutter shall be provided to ensure the following:-
10.8
a)
The circuit breaker cannot be inserted into the service position when in closed
position.
b)
The circuit breaker cannot be withdrawn from the service position unless it is
in open position.
c)
Access to the breaker chamber and circuit breaker shall not be possible
unless the breaker is withdrawn.
The circuit breaker shall be provided with rapid and smooth interruption of
currents under all conditions completely suppressing all undesirable phenomena on
even under the most severe and persistent short circuit conditions or when
interrupting small leading and lagging currents. The detail of any device or special
feature incorporated to limit or control the rate of rise of re-striking voltage across the
circuit breaker contact shall be stated. The over voltage caused by the circuit breaker
switching on inductive and capacitive loads shall not exceed 2.5 times the normal
phase to neutral voltage. The total break time for the circuit breaker throughout the
range of its operation duty shall be stated in the bid and it shall be guaranteed.
65
10.9
The circuit breaker shall be provided with suitable operating mechanism with
automatic recharging of spring with the help of geared motor. Provision shall also
exist for one detachable handle for manual charging in the event of failure of auxiliary
voltage. The switchgear shall be suitable for remote operations in addition to auxiliary
local operating mechanism. The operating mechanism shall be trip-free. All working
parts in the mechanism shall be of corrosion resistant material and all bearings,
which require greasing, shall be equipped with pressure grease fitting. The
mechanism, shall be strong, quick in action with minimum noise and shall be
removable without disturbing the other parts of the circuit breaker. The operating
mechanism alongwith its accessories shall be housed in a weatherproof cabinet with
hinged doors installed just adjacent to the breakers. The circuit breaker shall also be
provided with means for manual operation for maintenance purpose and local
tripping and closing. A local/remote change over switch shall also be provided.
Operating mechanism shall also be provided with operation counter and space
heaters with suitable thermostat switch to avoid condensation.
10.10 The control circuit shall be designed to operate on 110 V.D.C. supply with a variation
from 90% to 110% of rated voltage. A.C power supply for auxiliaries shall be
available at 240 V, single phase, 50 c/s. Provision shall be made for locking the
breaker mechanism in open position and locking the doors in closed position
through pad locks. Lamp indication as well as mechanical “open” and “close”
indication shall be provided on the switchgear panels to show the contact positions
of circuit breakers. Twelve numbers of the secondary auxiliary contacts shall be
provided on mobile portion of circuit breaker in any combination of NO and NC and
completely wired up to terminal blocks.
10.11
Means shall be provided for easy access to the contacts and other parts of the
switchgear for inspection and repairs. When these facilities are obtained by
provision of manholes, the manhole shall be of adequate dimensions and hinged
type and located in convenient place.
10.12 Bus Bars
All the bus bars within the switchgear assembly shall be air insulated and
shall be housed in a separate compartment of the switchgear assembly supported
on insulated supports. It shall have rated current capacity of not less than the rated
capacity of the circuit breaker. Bus bar shall also have mechanical and thermal
capacity not less than that represented by the short time current rating of the circuit
breaker. The bus bar shall be of aluminum conforming to relevant IEC, BS or Indian
standard. Phase-to-earth and Phase-to-Phase clearances shall also be in
accordance with IEC standards and corrections in the clearance on account of
altitude correction factor shall also be incorporated. No insulation sleeves shall be
provided on the bus bars to reduce the phase-to-earth and phase-to-phase
clearances. Support insulators shall be strong enough to take up dynamic forces on
account of short circuit. Temperature rise of the bus bars and joints shall also be as
per IEC standard. The bus bar phases shall be identified by painted bands of red,
yellow, & blue spaced at suitable distances.
10.13
Current Transformers
Current transformers CT-3, CT-4, Ct-5 depicted in drawings No. PHE-01-002 of Vol.
2C shall be mounted with in the cubicle and CT-1, Ct-2 shall be mounted on
66
generator marshalling box. All CT’s shall comply with the requirements of IS: 27051971 and its latest amendment.
Necessary steel brackets for mounting these CTs inside the cubicle shall also be
provided. The required CT ratio, burden and accuracy class shall be as mentioned
in section10.13.2. However, actual requirement will have to be worked out in coordination with other concerned suppliers and bidder should agree to accommodate
any change in requirement with regards to numbers and characteristics of CT’s at
the stage of approval of drawings. In addition to above technical particulars, the
CT’s shall have the following ratings also.
a)
Continuous current rating factor for secondary winding.
b)
Thermal short time rating one second with secondary short circuit, winding
temperature shall not exceed the limit as per IEC 185.
c)
Frequency: - 50HZ
10.13.1 All the routine tests, and tests at site shall be carried out on current transformers in
accordance with Indian standard with up to date amendments thereof. The tests to
be carried out by the Contractor shall clearly be stated in the bid. Type test
certificates shall be furnished by the contractor.
10.13.2 Other requirement of different CT’s are given below: S.N.
DESIGNATION
RATIO
PURPOSE
BURDEN
ACCURACY
CLASS
1
CT-1
1000/5
PROTECTION
50VA
5P10
2
CT-2
1000/5A
AVR
SENSING
50VA
0.5
3
CT-3
1000/5A
METERING
50 VA
0.5
4
CT-4
1000/5A
PROTECTION
50 VA
5P10
5
CT-5
2000/5A
PROTECTION
30VA
5P10
10.14
10.14.1
Voltage Transformers
Voltage transformers shall confirm to IS: 4156-1965 and its latest
amendments. Voltage transformers shall be provided as shown in drawing
No. PHE-01-002 of Vol. 2C & as per the schedule of requirement and be of
magnetic type. The voltage transformer shall be single-phase type and shall
be mounted inside the cubicle. Each transformer shall be complete with its
own high and low tension fuses and current limiting resistances if required.
The fuses shall be so arranged that they are readily accessible and
easily/quickly replaced. The burdens of PT’s are tentative only. The Bidder
shall indicate in his offer the actual burden imposed by relays, meters so that
modification, if required, in the rated burden of transformer can be done at the
time of placing of order. All the routine tests, type tests and tests after
installation given in relevant Indian Standard shall be carried and Bidders
shall give details of such tests which shall be carried out, with their offer.
10.14.2
Other requirement of Voltage transformer are given below: -
A)
Bus PT’s : Two No. Bus PT’s shall be provided as per rating given below :
Sr.No.
DESIGNATION RATIO
BURDEN
67
ACCURACY
CLASS
1
B)
CORE-I
415V/3/110V/3
50 VA
1
CORE-II
415V/3/110V/3
50 VA
3P
Generators PT’s : Two No. PT’s shall be provided on each generator
incommers as per rating given below :
Sr.No.
DESIGNATION RATIO
1
BURDEN
ACCURACY
CLASS
CORE-I
415V/3/110V/3
50VA
3P
CORE-II
415V/3/110V/3
50VA
1
CORE-III
415V/3/110V/3
100VA
1
10.15
Indicating Instruments
10.15.1
Indicating instruments shall be provided only on DG set incommer feeder and
LT panels feeders as depicted in single line diagram Drg.No. PHE-02-001. All
instruments shall be flush mounted on the top of the cubicle in a separate
compartment, see details as per attached schedule of requirement. The
instrument case shall be dust proof, water tight, vermin proof and especially
constructed to adequately protect the instrument against damage or
deterioration due to high ambient temperature and humidity. The instrument
shall be provided with all auxiliary appliances and any special tools required
for their maintenance.
10.15.2
All instruments shall be designed for accurate measurement of the
quantity or state under all conditions of operation and any error due to change
in ambient condition shall be kept to minimum. The instrument shall be
damped to comply with the requirement of clause 10.5 of IS 1248 or
equivalent. All the instruments shall comply with the requirement of first grade
instrument of switch board type vide IS:1248 or equivalent standard. All
instruments and meters shall be accurately, adjustable and calibrated before
shipment and shall have means for calibration, check and adjustment at site.
The metric unit shall be used for displaying the values. The instrument shall
be capable of withstanding over loads applied in accordance with IS:1248 or
equivalent. The instrument shall be capable withstanding the following tests,
viz effect of shock, vibration and effect of humidity.
10.15.3
10.16
Panels
10.16.1
All enclosures and Panels/Cubicles shall be of good quality Standard
production. Panels/cubicles shall be free floor standing type of rigid frame
covered with removal steel sheets. The frame should be bolted to floor. There
shall be provision and enough space for entrance of cables from below. The
cubicles shall be ventilated if needed, in this case removal filter inserts shall
be fitted to the air entrance openings. Provision for cable fastenings shall be
made inside the cubicles and enclosures and sufficient space for cable
fastenings to nearest terminals shall be kept. All control and indicating
instruments such as contactors, circuit breakers, auxiliary relays, indicating
instruments, switches etc. shall be functionally displayed in appropriate
locations. The layout is subject to approval of the Engineer –in- charge,
however, standard layout of the manufacturer is acceptable with minor
changes if required. The panels/cubicles should be of IP-20 protection class
and the outside paint shall be powder coated, pebble gray (RAL 7032) and
68
inside either pebble gray or enameled white. No other shade shall be
accepted.
10.17
MIMIC Diagram:
Overlaid mimic diagram using 10 x 2 mm aluminum strips to depict the circuit
as per the single line diagram shall be provided. The colour coding shall be as
per I.S. 11954 – 1987.
10.19
Earthing Arrangements
Two separate copper earth buses of suitable cross-sectional areas shall be
provided in the 500V switchgear designed for a short circuit current of 8 kA.
One earth bus shall run along the entire rear length of the switchgear panels
and the lightning arrestors shall be connected to this earth bus. The other
earth bus shall be run along the entire front side of the switchgear panel and
the earth connections from the relays and control devices shall be made to
this bus. Both the earth buses shall be connected to the station M.S. earth
bus at the extreme ends using bi-metallic joints. The earthing inside the
panels shall be done using green coloured PVC flexible copper cables.
10.20
Terminal Blocks
(i)
All terminal blocks shall be mounted in an accessible position with the
spacing between adjacent blocks not less than 100mm and the space
between the bottom blocks and the cable gland plate being a
minimum of 200mm. Sufficient terminal shall be provided to allow for
the connection of all incoming and outgoing cables including spare
conductors and drain wires. In enclosed cubicles, the terminal blocks
shall be inclined towards the door for facilitating terminations. At least
20% spare terminal shall be provided.
(ii)
The terminals shall be of the channel mounting type and shall
comprise a system of individual terminals so that terminal blocks can
be formed for easy and convenient cabling consistent with the high
reliability required of the circuits.
(iii)
The terminal blocks shall be provided with shorting links and
paralleling links where applicable, and mounted identification numbers
and/or letters.
(iv)
The terminal blocks shall conform to the applicable NEMA standard.
The smallest size to be used shall be designated for 2.5 millimeter
square wire and no more than two (2) conductors shall be connected
under one terminal clamp.
(v)
Terminal identification shall be provided corresponding to wire number
of connected leads.
(vi)
Power circuit terminals shall be segregated from other terminals and
shall be equipped with non-inflammable, transparent covers, to
prevent contact with live parts. Warning labels with red lettering shall
be mounted thereon in a conspicuous position.
(vii)
Disconnecting type terminals shall be provided for the Current &
Voltage connections and non-disconnecting type used for other
control circuits.
(viii)
One common alarm annunciator shall be provided in one of the VCB
panels to annunciate the trip and non trip alarms. The annunciator
69
10.21
shall have automatic silencing facility i.e. the audio alarm shall silence
off after one minute if the same is not acknowledged. However the
alarm window shall remain lighted till the same is reset or the fault
cleared.
Mandatory Spares
Following mandatory spares shall be supplied :-
10.22
ACB
1000A
1 No.
ACB
2000A
1 No.
Trip Coil
2 No.’s
Closing Coils
2 No.’s
Erection and Commissioning at site : -
10.22.1
The Contractor shall furnish all labour, tools, tackles, slings and support and
all other provisions or materials necessary to assemble, erect, install, test and
commission the 415 V ACB’s in a thorough workmanlike manner following the
best modern practices. The VCB’s and all their components shall be placed
with great care and shall be aligned correctly.
10.22.2
The panels/cubicles shall be provided with complete set of foundation holding
down bolts, washers, nuts, plates and other fixtures as may be required and
these shall be supplied by the Contractor.
10.22.3
All test equipments and instruments shall be provided by the Contractor free
of charge and shall remain the Contractor’s properties after the fulfillment of
the field tests.
10.22.4
All civil works required for foundation shall be carried out by the Owner or his
representative. The Contractor is required to submit the foundation drawings
and supporting steel well in time.
10.23
Tests
10.23.1
Type test certificates of tests listed in the subsequent clauses, to ensure the
quality and capability of the offered equipment, must accompany the bid
documents. The Bidder shall specify the details of measurement and
conducting of these tests alongwith the bid.
10.23.2
All the tests to be carried out on all the equipment shall conform to IEC, BS
and Indian Standard. Bids not accompanied with the relevant type test
certificate confirming to IEC & IS shall be liable to rejection.
10.23.3
Routine Tests : Routine tests shall be carried out on each equipment in the
presence of Owner’s representative at the manufacturer’s expenses at his
works.
10.23.4
Circuit Breaker
i)
TYPE TEST
1.
Short circuit tests comprising of: -
a)
Breaking capacity tests for recovery voltage, the symmetrical and
asymmetrical breaking currents, amplitude factor and rate of rise of
recovery voltage.
Making capacity tests for applied voltage and making current.
Test duty.
Short time current tests.
a)
Temperature rise test of the main circuit.
b)
Temperature rise test of the auxiliary circuit.
c)
Measurement of the resistance of the main circuit
b)
c)
d)
2.
70
10.23.5
10.23.6
3
Operational tests.
4
Mechanical endurance tests
5
a)
Impulse voltage withstand test.
b)
One minute power frequency withstand voltage test.
ii)
ROUTINE TEST
1
Operation test.
2
Measurement of the resistance of the main circuit.
3
One minute power frequency voltage withstand test.
Potential Transformer :
i)
TYPE TEST
1.
Verification of terminal marking and polarity.
2.
Induced Power frequency test on primary winding
3
Induced Power frequency test on secondary winding.
4.
Determination of errors according to the requirement of the
appropriate accuracy.
5.
Temperature rise test.
6.
Impulse voltage test.
ii)
ROUTINE TEST:
1
Verification of terminal marking and polarity.
2.
Induced Power frequency test on primary winding
3
Induced Power frequency test on secondary winding.
4.
Determination of errors according to the requirement of the
appropriate accuracy.
Current Transformer :
i)
TYPE TEST
1
Verification of terminal marking and polarity.
2.
High voltage power frequency on primary winding
3
High voltage power frequency test on secondary winding
4.
Over voltage interturn test
5.
Determination of errors according to the appropriate accuracy class.
6.
Short time current test.
7.
Temperature rise test.
8.
Impulse voltage test.
ii)
ROUTINE TEST :
1.
Verification of terminal marking and polarity.
2.
High voltage power frequency on primary winding
3
High voltage power frequency test on secondary winding
4.
Over voltage interturn test
5.
Determination of errors according to the appropriate accuracy class.
71
10.23.7
iii)
ADDITIONAL TESTS FOR MEASURING CT’s
i)
Accuracy test
ii)
Instrument security current test.
iv)
ADDITIONAL TESTS FOR PROTECTION CT’S
a)
For class 5P10
i)
Current error and phase displacement test
ii)
Composite error test
b)
For class PS
i)
Knee point voltage
ii)
Exciting current
iii)
Secondary winding resistance
iv)
Turn ratio
Site Tests: All the equipments supplied shall be tested at site after successful installation
as per the recommendation of IEC or equivalent Indian Standard. Details of
the test and standard according to which these tests shall be carried out
should accompany the bid. Any other test specifically required to prove the
successful installation of the equipment shall also be carried out. The
Contractor shall indicate details of tools plants and instruments required for
site testing.
72
SECTION-XI
TECHNICAL SPECIFICATION FOR 415 VOLTS AC DISTRIBUTION BOARD
11.1.0 Scope :This section of the specification cover the following scope of works: i)
ii)
Dismantling/removing of existing 415 V LT switch Board, all services, at
labour, tools and tackles required for dismantling including carriage, stacking
Owner’s store/ yard.
Design, engineering, manufacture, shop assembly & testing before dispatch,
packing and forwarding, transportation, insurance, handling, delivery, storage
at site, erection, testing & commissioning of 415 V AC Distribution Board, as
detailed in this specification and handing over to HPSEB LTD. complete with
accessories, equipment, devices, & fitting, instruments, cabling and wiring
etc. including all services, labour, tools and tackles.
11.2.0 Type and Rating of 415 V AC Distribution Board :A.C. incomer circuits shall be controlled through power contactors and MCCB’s as
depicted in drawing No. PHE-01-002 of Vol.-II. The outgoing feeders shall be
moulded case circuit breakers (MCCB).
The 415 volts Power contactors shall have the following ratings:i)
ii)
iii)
iv)
No. of poles
Service voltage
Normal current
Frequency
3
415 V.
150 A.
50 Hz.
11.3.0 Standards:The power contactors and MCCB’s shall comply in all respect with the requirement
of latest issue of Indian.
The L.T. switchgear shall comply in all resects with the latest editions of the following
Indian Standards:I.S. 8623
Specification for factory built assemblies of switchgear and
control gear ; Voltages up to and including 1000 V A.C and
1200 V. D.C.
I.S. 4237
General requirement for switchgear and control gear for
voltages not exceeding 1000 volts
I.S. 2147
Degree of protection provided by enclosures for L.V.
Switchgear and Control gear.
I.S. 2705
Specification for current transformers.
I.S. 3156
Specification for voltage transformers.
I.S. 3231
Specification for electrical relays.
One number authorized copy of all the applicable standards (IS or IEC) shall be
supplied after the award of work.
11.41 Particulars of 415 V System :The system for supplying A.C. power to the various auxiliaries of the generating units
and the station is as per the single line diagram No. PHE-02-001 of Vol. 2 C.
73
11.5
Constructional Features :Switchboards shall be:-
i)
ii)
iii)
iv)
v)
vi)
vii)
viii)
ix)
x)
xi)
xii)
xiii)
xiv)
xv)
xvi)
xvii)
xviii)
xix)
xx)
Of the metal enclosed indoor, floor mounted, modular, free standing type.
Made up of requisite vertical sections.
Provided with a metal sill frame made of structural steel channel section properly
drilled for mounting the switchgear alongwith the necessary mounting hardware.
Hardware shall be zinc plated and passivated.
The switchgear shall be capable to withstand earthquake forces giving dynamic
accelerations of 0.5g in all the three directions at a frequency of the order of 10
cycles per second. The details of the calculations made for the designs of the various
equipment’s taking into account the above seismic forces shall be furnished to the
purchaser.
Provided with a degree of protection IP-51
Provided with labels on the front and rear indicating the switchgear designation
compartment wise and cubicle with the labels shall be fixed with the help of screws
and not with an adhesive.
Provided with cable entry facilities at bottom with 3mm thick removable gland plates
and necessary cable glands.
Of uniform height of not more than 2450mm including the base channels. The height
of pillar boxes can be different but not more than 2450 mm height.
Provided with gaskets all round the perimeter of adjacent panels, panel and base
frame, removable covers and doors.
Provided with bus bars running at the top as required all along the length of the
switchgear in separate sheet steel enclosures.
Operating devices shall be incorporated only in the front of the switchgear.
Individual feeder modules shall be arranged in multitier formation.
Enclosed vertical bus bars serving all modules in the vertical section shall be
provided. For safety, isolation of the vertical bus bars, insulation barrier with cutouts
shall be provided to allow the power contacts to engage with vertical bus bars.
A vertical cable alley covering the entire height shall be provided. The cable alley
shall be minimum 200m wide.
A horizontal separate enclosure for all auxiliary and control buses, as required, shall
be located so as to enable easy identification, maintenance and segregation from the
main power buses. Tap off connections from these buses shall be arranged
separately for each vertical section.
Each vertical section shall be equipped with space heaters.
Metal sheet shall be provided between the adjacent vertical sections running the full
height of the switchgear except the horizontal bus bar compartment. Also each
shipping section shall have metal sheets at both ends.
All equipment associated with a single circuit shall be in a separate module
compartment of the vertical compartment shall be sheet steel enclosed on all sides
and for draw out type modules only the handles of control selector switches- push
buttons, knobs and cutouts for lamps and meters shall be arranged on the front door
respective compartments to permit operation without opening the door. On circuit
breaker controlled circuit protective relays shall be mounted on the front door the
compartment. All cut outs shall be provided with gaskets for the purpose of dust
proofing. The opening of the doors shall be restricted to 1100 only.
All current transformers on circuit breaker controlled circuits shall be mounted on the
fixed portion of the compartment.
In breaker compartment suitable barriers shall be between circuit breakers and all
control, protective indication circuit equipment including instrument transformers.
External cable connections shall be carried out separate cable compartments for
power and control cable.
74
xxi)
xxii)
xxiii)
xxiv)
xxv)
After isolation of the power and control connection of circuit, it shall be possible to
safely carryout main in a compartment with the bus bars and adjacent circuit live.
Cable alleys shall be provided with suitable hinged. It shall be possible to safely
carryout maintenance on cable connections to any one circuit with the bus and
adjacent circuits live. Adequate number of slot cable support arms shall be provided
for cleating the cables
Rear of the single front switchgear shall be provided removable panel covers hinged
on one side and bolted the other side.
All doors shall be provided with concealed type hinged captive screws.
The neutral bus shall run continuously in the bus bar chamber and shall be solidly
connected to ground bus bar. The housing shall be complete with adequate
ventilation and heaters with all openings screened. All switches shall be designed to
permit extension in either direct and shall be complete with all accessories including
fixtures, foundation bolt, base channel etc. for securing the switch board to the floor.
The switchyard and the service bay shall be weather proof and shall be of the same
specifications described above
11.6
Earthing:The assembly comprising of chassis, framework and the fixed parts of the metal
casing of the switchgear or control gear shall be provided with separate earthing
terminals and should conform to IS- 4237.Bimettalic strips shall be provided for
connecting the earthing bus with the station earth mat.
11.7
Power Cables and Sealing Ends :All power cables and control cables for connection to the switchgear will be brought
from the bottom of the switchboard. Crimping type cable sealing ends suitable for
aluminium cables of suitable sizes shall be supplied with each circuit of the
switchgear. The exact dimension and number of such cable sealing ends shall be
informed to the successful bidders after finalization of cable sizes. Cabling
terminations shall be staggered along the depth of the board to allow cabling without
difficult bends. Suitable arrangements shall be provided to hold the cables along the
height of the panel so that the weight of the cable does not come on the cable
sealing lugs. The terminals shall be of substantial mechanical construction and
should conform to clause 5.3 of IS- 4237-1967.
11.8
Control Cables :All the control cables shall be terminated at the terminal blocks located in the
switchgear frame and should be in a separate compartment other than the
compartments where the power cables are terminated. These terminal blocks shall
be suitable for 2.5mm multistrand copper, P.V.C. insulated cable, 1.1KV conforming
to IS- 694 (1977)/IS-8130(1976). The terminal blocks used for cables from current
transformers and potential transformers shall be of disconnecting type.
11.8.1 The switchboards shall be completed with all accessories including bus bars, bus bar
chambers, supports, wiring, terminal blocks, labels, foundation fixture, earthing
conductors, cable sealing ends, cable glands and gland plates etc. These will be
climate proof as per the requirement of IS-3202
11.9 MCCB’s :The MCCB’s shall have inbuilt over current, earth fault and under voltage
protection.
75
11.9.1 Switch board shall be designed on flush fronted principle with circuits arranged in
multiple tier formation.
11.9.2 The incomer MCCB’s shall be provided with inbuilt over current and earth fault
protection with settings to suit the full load values of the individual’s currents of the
circuits.
11.9.3 Additional contacts or auxiliary relay with contacts shall be provided for interlocking
inclosing circuits. Also if sufficient number of auxiliary contacts are not available with
over current relays of these breakers, auxiliary relay shall be provided for use in
interlocking.
11.9.4 All the outgoing feeders shall be provided with moulded case circuit breakers
(MCCB) having suitably designed thermal magnetic overload protection. These
protections shall be ambient temperature compensated for operation between -370 C
to 400C.
11.9.5 The MCCB shall be manually operated. The operating handle shall give a clear trip
indication. It shall assume a point midway between 'ON' and 'OFF' positions on
tripping. To reset the trip mechanism, the handle shall be moved to the 'OFF'
position.
11.9.6 The MCCB shall be quick make/ quick break, trip free and independent of manual
speed for operation.
11.9.7 The breaking capacity shall be tested for P-2 class duty cycle as per IS- 2516. The
breaking capacity test report shall be from a Government recognized test laboratory.
MCCB shall be provided with direct acting magnetic thermal release for short circuit
and overload protections. Settings of the thermal release shall be independent
adjustable over a wide range percentage of nominal rating in all ranges.
11.9.8 The main contacts of the breakers shall be of appropriate silver alloys and
mere silver plating of the faces will not be acceptable.
11.9.9 The type of arcing contacts and arc contact device shall be silver alloy arc
chutes having profiles de-ion plate.
11.9.10 The mechanical life certificate shall be from Govt. recognized test house and shall be
accompanied with the offer.
11.9.11 The temperature rise of various parts of the MCCB shall be in conformity to IS: 2516
and test certificate from Govt. Recognized test house shall be produced at the time of
detailed engineering.
11.9.12 The power contactor shall be suitable for continuous current rating of 150 A .
11.9.13 The cubicles should comply with the requirement of relevant Indian Standard and
Electricity Rules for providing minimum clearances between phases of the bus, live
part from metalled cubicle. The drawing showing full dimensions of the cubicles
alongwith size of the sheet used for manufacture should be got approved from this
office before starting the fabrication of the cubicles. The colour of the paint to be
applied to the cubicles shall be got approved from this office before final painting.
The colour of the paint shall be RAL7032, pebble grey from outside and enamel
white from inside.
76
11.9.14 All control wiring of the cubicle shall be done with 2.5mm copper cable with suitable
numbering using plastic ferrules and suitable colour code for C.T. & P.T. cables. The
cables should be PVC insulated of 1.1KV class conforming to IS: 694/IS 8130.
11.9.15 The Power Contactors and MCCB’s shall be either of ABB (E.max)/L&T (U
power)/Snider (Master pact)/Siemens (3VL)/C& S.
11.10
Bus Bar and Bus Bar Chambers:-
The 415 volts bus bars shall be of suitable cross section so as to carry the required
current within the limits of temperature rise at the site conditions. They shall be so
designed and mounted in the chamber that expansion or contraction does not subject
either the bus bar or the insulating supports to any undue stress.
11.10.1 The bus bars shall be designed to withstand safely the dynamic forces due to short
circuit.
11.10.2 Neutral links of suitable capacity shall be provided where ever necessary.
11.10.3 The bus bars shall be made of high conductivity aluminium grade 91-E (6101 A) high
strength ionized aluminium alloy of suitable size. Bus bar shrouds shall be easily
removable so that the joints are
accessible for maintenance. The connections
from bus bars to the ACB's shall be fully shrouded with PVC covers.
11.10.4 Adequate space shall be there to connect aluminium bars of different rating.
11.10.5 The bus bars shall withstand short circuit faults upto 16KA (rms.) for 1 sec. All the
bus bars shall be braced with non- deteriorating SRBP supports to withstand thermal
and electro-dynamic forces of fault current.
11.11 Temperature Rise :The switchgear shall be designed to operate satisfactorily under the site conditions
and the maximum temperature attained by any part of the equipment wherein service
at an ambient temperature of 40oC shall not exceed the limits specified under clause
6 of IS- 4237 corrected for the site conditions, when measured by variation of
resistance method as given in Appendix-C of the Indian Standard IS- 4237.
11.12 Auxiliary Relays, Contacts and Devices :Suitable number of auxiliary contacts or auxiliary relays shall be provided with air
circuit breaker for indication annunciation and automatic changeover and interlocking
scheme.
11.13 Current Transformers
Current transformers CT-8 depicted in drawings No. PHE-01-002 of Vol. 2C shall be
mounted with in the cubicle of incomer circuit and shall comply with the
requirements of IS: 2705-1971 and its latest amendment.
Necessary steel brackets for mounting these CTs inside the cubicle shall also be
provided. The required CT ratio, burden and accuracy class shall be as mentioned
in section11.13.2. However, actual requirement will have to be worked out in coordination with other concerned suppliers and bidder should agree to accommodate
any change in requirement with regards to numbers and characteristics of CT’s at
the stage of approval of drawings. In addition to above technical particulars, the
CT’s shall have the following ratings also.
a)
Continuous current rating factor for secondary winding.
77
b)
Thermal short time rating one second with secondary short circuit, winding
temperature shall not exceed the limit as per IEC 185.
c)
Frequency: - 50HZ
11.13.1 All the routine tests, and tests at site shall be carried out on current transformers in
accordance with Indian standard with up to date amendments thereof. The tests to
be carried out by the Contractor shall clearly be stated in the bid. Type test
certificates shall be furnished by the contractor.
11.13.2 Other requirement of different CT’s are given below: S.N.
1
DESIGNATION
RATIO
PURPOSE
BURDEN
ACCURACY
CLASS
CT-8
150 /1A
METERING
50 VA
0.5
11.14
Voltage Transformers
11.14.1
Voltage transformers (PT-5) shall confirm to IS: 4156-1965 and its latest
amendments. Voltage transformers shall be provided as shown in drawing
No. PHE-01-002 of Vol. 2C & as per the schedule of requirement and be of
magnetic type. The voltage transformer shall be single-phase type and shall
be mounted inside the cubicle. Each transformer shall be complete with its
own high and low tension fuses and current limiting resistances if required.
The fuses shall be so arranged that they are readily accessible and
easily/quickly replaced. The burdens of PT’s are tentative only. The Bidder
shall indicate in his offer the actual burden imposed by relays, meters so that
modification, if required, in the rated burden of transformer can be done at the
time of placing of order. All the routine tests, type tests and tests after
installation given in relevant Indian Standard shall be carried and Bidders
shall give details of such tests which shall be carried out, with their offer.
11.14.2
Other requirement of Voltage transformer are given below: Incomer PT’s : One No. PT’s shall be provided on each incomer as per
details given below :
Sr.No.
1
DESIGNATION RATIO
PT-5
415V/3/110V/3
BURDEN
50 VA
ACCURACY
CLASS
1
11.15
Indicating Instruments
11.15.1
Indicating instruments shall be only on incommer feeder as depicted in
Drawing.No. PHE-02-001 of Vol. 2C. All instruments shall be flush mounted
on the top of the cubicle in a separate compartment, see details as per
attached schedule of requirement. The instrument case shall be dust proof,
water tight, vermin proof and especially constructed to adequately protect the
instrument against damage or deterioration due to high ambient temperature
and humidity. The instrument shall be provided with all auxiliary appliances
and any special tools required for their maintenance.
11.15.2
All instruments shall be designed for accurate measurement of the quantity or
state under all conditions of operation and any error due to change in ambient
condition shall be kept to minimum. The instrument shall be damped to
78
comply with the requirement of clause 10.5 of IS 1248 or equivalent. All the
instruments shall comply with the requirement of first grade instrument of
switch board type vide IS:1248 or equivalent standard. All instruments and
meters shall be accurately, adjustable and calibrated before shipment and
shall have means for calibration, check and adjustment at site.
The metric unit shall be used for displaying the values. The instrument shall
be capable of withstanding over loads applied in accordance with IS:1248 or
equivalent. The instrument shall be capable withstanding the following tests,
viz effect of shock, vibration and effect of humidity.
11.15.3
11.16
Tests:Each switchboard shall be assembled at the manufacturers work with all
apparatus instruments & meters connected up and the various components
shall be tested in accordance with the requirements of the relevant Indian
Standards. Each circuit breaker shall also be subjected to manufacturer’s
standard routine tests in accordance with IS: 13947-2, 2516. These tests shall
be performed in the presence of purchaser's representatives, if so desired by
the purchaser.
Type test certificate of short circuit level of 16KA withstand capacity shall be
submitted by contractor.
11.16.1
1.
2.
3.
4.
5.
11.16.2
The following type tests shall be carried out :-
1.
2.
3.
4.
5.
6.
11.17
The following routine tests shall be carried out :Mechanical operation test.
High voltage test.
Test for verification of calibration of release.
Milli-voltage drop test.
Type test reports for proof of having tested the MCCB’s in the recognized
Govt. Test house for the following type tests as per IS shall be furnished.
Temperature rise test for main contacts.
Temperature rise test for control circuits.
Temperature rise test of auxiliary contacts.
Verification of the rated short circuit making & breaking capacities.
Verification of the ability to carry rated short time current.
All test reports should be submitted and shall be got approved by the owner
before despatch of the equipment.
Test Certificates :Seven copies of instruction manual covering instructions for installation,
operation,
maintenance shall be supplied by the renderer.
11.18
Control Voltage :All the circuit breakers shall operate satisfactorily with the control voltage of
110
volts D.C. between the range of 85% to 110% of the rated voltage and
ambient temperature of -350C to + 400C.
11.18
Marking of Push Buttons :79
Push buttons should be indelibly marked in words as per clause 10.1 and
colour of the push buttons shall be as per clause 10.2 of IS: 4237.
Selection and treatment of the materials use electrical equipment and
enclosures and
sealing of the equipment to ensure that it remains
serviceable under conditions which may encourage chemical, physical and
mechanical deterioration/ prevailing at
site and adequate climatic
proofing shall be as per IS : 3202. The bimetallic strips
shall be annealed
before assembly to climatic aging.
11.20
Spares :The Bidders shall quote for the following mandatory spares :1
2
3
4
3
11.21
Power Contactor
MCCB (TP)
MCCB (TP)
MCCB (DP)
MCCB (DP)
150A
30A
15A
30A
15A
1 No.
1 No
1 No
1 No
1 No
Detail of Incoming Feeders :
A) Incomer from 415 V P/H Bus
B) Incommer from Station Transformer.
Interlocking : Either power contactor shall be ON and both cannot be switched
ON simultaneously. Interlocking Arrangement shall be made in panels.
11.20
Detail of Outgoing Feeders
A) Double Pole MCCB feeders (Single Phase Supply) :
1
ACB Control Supply
30 A
2
VCB Control Supply
30 A
3
Protection Panels
15 A
4
Power House Illumination
30 A
5
Street/Yard Lighting
30 A
6
Turbine Auxiliary and control panel
15A
7
Spare Feeders
15 A
30 A
B) Triple Pole MCCB Feeders :-
Qty
1 No
1 No
1 No
3 No’s
2No.’s
4 No’s
1 No.’s
1 No.’s
1
2
3
4
6
7
8
4 No.’s
4 No.’s
1 No.
1 No
4No.’s
4 No.’s
1 No.’s
1 No.’s
of detailed
Oil Pressure Unit for Turbine and MIV
Generator Lub Oil System
Power House Crane
Battery Charger
Dewatering Pump
Generator space heating
Spare Feeders
30 A
15 A
50 A
30 A
30 A
20 A
15 A
30 A
Above list is tentative. Actual quantity / rating may vary at the time
engineering.
80