Download capacitor banks - Schneider Electric Belgique

CAPACITOR BANKS
General
This part of the specification covers the design, manufacture, delivery, transportation, and
commissioning of capacitor banks. The capacitors shall be installed indoors or outdoors as specified
along with the related inrush current reactors, switching facilities and protections.
All necessary equipment for the control, protection and supervision of the capacitor banks is also
deemed to be included.
The capacitor bank shall be factory mounted to a maximum possible extent to reduce the work
required at site.
The capacitor banks shall be designed as compactly as possible in order to reduce space
requirements.
The capacitor banks shall be designed for temperature class D (max. 55° C) for outdoor installation
and class B (max. 45° C) for indoor installation.
Capacitor Units
The capacitor banks shall comprise a series of single phase capacitor units suitably designed for the
required total amount of reactive power for the specified frequency and voltage.
The capacitor containers shall be of steel with an adequate corrosion protection. The final coat shall
comply with RAL code 7038 « light grey ». The tenderer will submit along with its offer the painting
specification for approval.
The guaranteed minimum values of losses of the capacitor units shall include losses due to discharge
resistors which shall be mounted inside each unit to discharge each unit from peak voltage to
maximum 75 V in less than 10 minutes.
Internal fuses shall be provided in order to limit possible failure to a single capacitor element only.
The capacitors shall be able to carry continuously 1.3 times the rated current 1.1 times the maximum
system voltage and shall provide continuously 1.35 times the rated output. All the above requirements
shall be fulfilled under maximum ambient temperature.
The dielectric material shall consist of an all film material being suitable to operate the capacitors on
continuous load under the specified ambient conditions. The impregnant shall be of a hydrocarbon
type fluid characterised by high electrical strength and adequate physical and chemical properties and
shall be non-PCB. Low toxicity is required and the impregnant shall be a class III B (OSHA
classification) combustible fluid.
Each capacitor shall have one or two bushings dependent on the mounting arrangement. For outdoor
installation a creepage distance of 50 mm/kV for open rack material or 25 mm/kV for complete
inclosed material and for indoor installation of 25 mm/kV shall be considered.
The arrangement of the fixing and the bushings shall be identical in order to easily exchange and
replace any capacitor element of the total capacitor bank. The terminals for bushings and fixing
elements shall be ISO standard (metric).
Capacitor bank
A number of capacitor units shall be combined to capacitor banks in double star arrangement. The
modules shall be arranged as an assembly on suitably designed enclosure and constructional
members of aluminium to avoid any corrosion problem .
The capacitor banks shall include all necessary internal connections and busbars, insulators and other
fittings. The capacitor enclosure structure shall be designed to carry all required unit capacitors and
facilities, and the conductors comprising the incoming and outgoing circuits under the loadings and
factors of safety specified and to give the minimum phase and earth clearances.
The safe removal and safe replacement of capacitor units shall minimise the dismantling of any
structural member, support, including insulators or main connections.
Where necessary, approved means shall be provided upon the capacitor equipment for the fixing and
bonding of external connections to secure efficient earthing. Steelwork and all items of the capacitor
equipment shall be bonded as necessary with copper straps of adequate cross-section. In case of
outdoor open rack installation tinned copper shall be used.
Approved facilities shall be provided to temporarily earth the connections and apparatus during
maintenance.
Switching device
Source circuit breaker
The …KV Source circuit breaker is excluded from the scope of supply of the multi-stages capacitor
bank equipment. The contractor shall verify with the purchaser that the nominated source circuit
breaker is suitable for capacitor switching duties. Tenderers shall state in their tender the circuit
breaker requirements for the capacitor bank being offered
Capacitor switches
Each stage shall be controlled by a suitable SF6 circuit breaker for switching in and out the respective
capacitor stage, according to the capacitive demand required by the system operating conditions
The tenderer shall provide details of the proposed circuit breaker in his tender, together with evidence
that they are suitable for switching duties and that the circuit breaker and associated power equipment
will not be subject to damaging over-voltages when switching.
Safety interlocking and Earthing
Interlocking shall be provided to ensure that the access to the capacitor bank enclosure is not possible
until the associated main incoming circuit breaker has been racked and the faulty stage has been
locked out and circuit earth applied.
One earthing switch shall be provided in each capacitor stage and will be placed after the automatic
circuit breaker. For safety raison this earthing switch will be also interlocked with the main outgoing
feeder
Reactor and discharge device
Current limiting reactor
The transient current that flows on energising shall not exceed the rated making current of the circuit
breaker controlling the capacitor bank stage. If necessary, current limiting reactor shall be connected
in series with each capacitor stage to limit the current to an acceptable value. The current calculation
which flows upon energising shall be declared and shall take into account the contribution from
parallel connected capacitor stages
Current limiting reactors shall be designed for the full system lightning impulse withstand level
The reactor shall be dry air cored, mounted on suitably rated support insulator
Discharge devices
Discharge resistors, suitable to discharge the capacitors from peak rated voltage to less than 75 volt
within 10 minutes shall be fitted within the capacitor container. Tenderer shall also propose suitable
fast-discharge devices for consideration that will achieve de-energisation in less than 30 secondes
Capacitor Protection
The capacitor banks/units shall be provided completely with its internal and external protection which
is considered as part of the capacitor equipment. Nevertheless, the general stipulations of Article
shall be applicable as far as essential. Protection relays shall be of the numerical type.
Fuses
Fuses shall be provided internally for protection of individual capacitor units. The fuses shall not
deteriorate when the capacitor is subjected to discharge testing nor the currents associated with
service operations of the capacitor equipment. Fuses shall only rupture in case the related unit is
subject to failure and shall be capable of breaking the current following a failure of the capacitor unit
without hazard from the fuse or the capacitor. The ruptured fuse of each element shall withstand
indefinitely the voltage imposed across it under all operating conditions.
The remaining capacitor units shall be able to operate within the capacitor bank without undue
disturbance for a present number of unit capacitor failures.
Unbalance Protection
Sensitive loss of capacitance and fuse failure detection and alarm facilities shall be provided.
The protection shall comprise two independently adjustable steps with separate alarm and tripping
contacts at each stage. The first stage is set to operate an alarm when a significant number of
capacitor units have failed and the second stage shall initiate tripping after a reset time delay via a trip
relay (block-close function) before the loss of capacitance has resulted in an unacceptable overloading of any capacitor. The Tenderer shall submit a table showing the number of units that can be
lost per phase and per series group for a period of 1 month without derating of the capacitor bank and
without reduction in the designed life of the capacitor. The minimum number of unit capacitors to
satisfy these requirements shall not be less than one.
The protection shall be insensitive against inrush and harmonic currents.
Overload and Over-current Protection
For each phase of each capacitor bank an overload and overcurrent protection system shall be
provided to protect the capacitors from excess current (rms), including harmonic currents.
Overload protection
A first alarm shall be given at a current of approx. 110 to 120 percent of the rated current if applied for
more than approx. 30 min. A second alarm (selectable by links for tripping as well) shall be initiated at
currents of 120 to 140 percent of the rated current suitably time delayed to avoid spurious alarms
(trippings) being situated during short time disturbances.
Each stage of the overload protection shall be independently adjustable.
Over-current protection
For currents above 140 percent of the rated current a time delayed relay shall be provided to initiate
tripping. An instantaneous element for initiating tripping at currents above 200 percent of rated current,
however properly secured against tripping due to inrush currents shall be added per phase with
separate alarm and trip contacts. Reference is made to the MV over-current relays specified in Article
of these specifications.
Over-voltage protection
The CONTRACTOR shall propose and provide suitable over-voltage protection devices to control
transferred, internal and external over-voltages on the capacitor banks.
Loss of Capacitance
Facilities shall be provided to allow for safe, simple and quick identification of defective capacitor units.
Portable test equipment or other means shall be supplied being able to detect defective units.
Protection scheme
The protection scheme shall be designed to isolate the faulted capacitor stage without disruption to
the other stages. Schemes which require tripping the main incoming feeder circuit breaker are not
acceptable
Over-voltage aver-load and unbalance protections may be combined within proprietary relay designed
specifically for protection of capacitor banks
Capacitor Bank Control
The capacitor banks connected to each of the xxx kV busbars via one outgoing xxx kV feeder shall
consist of one …. X … Mvar or …. X ….Mvar. Automatic and manual switching control shall be
provided for the different stages. Automatic control shall be preferably provided by a numerical type of
reactive power regulator including harmonic current supervision and.
The operating mode of each capacitor bank shall be selectable via an Auto/ Manual / Off switch. There
shall be On / Off push buttons for manual Close/trip. Manual closing shall only be possible with the
selector switch in Manual position. Time delay facilities shall be provided in the manual control circuit
to inhibit any re-closing within a set delay time. Delay time shall be adjustable over the range of 0-5
minutes
The automatic control unit will initiate switching f the appropriate number of stages in or out of service.
The control unit shall select the capacitor stage to be switched in and means shall be provided to vary
the duty cycle to ensure a reasonable distribution of switching operations between different capacitor
stages.
The control system shall provide facility for manual / remote switching out, both locally and remotely
from the control centre. Suitable indications of the status of the capacitor bank shall be provided
locally and made available for signalling to the control centre.
The detailed design of the control and indicating system shall be submitted for approval
Control Panel
A modular panel housing the individual and master controllers is required to be supplied and will be
installed in the control room of the substation. The enclosures shall provide at least IP42 protection to
the control equipment.
The capacitor bank will be controlled by a logic control scheme as specified in section below.
Controller
The controller shall automatically switch of the Capacitor Banks in the event of loss of the 22 kV
supply. The scheme must be capable of re-starting automatically following restoration of supplies.
The automatic sequence of switching IN/OUT of the capacitor units in stages shall be controlled by a
programmable logic controller of the power factor controler (PFC).
The switching sequence shall be coordinated with the logic control of the sub-station. device and
Voltage Control (VC) device, and these shall be selectable from manual selection facilities. The
switching steps shall be programmable to achieve switching of capacitor sub-banks through stage
controlled circuit breaker.
Tenderers shall state the substation parameters that are necessary for implementation of the control
system, including the required specification of the main transformer CT’s.
A flow chart detailing the switching sequences shall be included in the Tender.
Power Factor Control
The PFC relay/equipment shall have a range suitable for proper selection of switching In/Out of the
Sub-banks to maintain the Target Power Factor via the PLC. The relay PF setting range shall be.
0.8 CAPACITIVE – UNITY –0.8 INDUCTIVE
The relay shall have as a minimum a digital display of PF, Target PF, Operation Time Delay,
voltage and current. Details of the PFC equipment/manufacturer shall be given in Schedule C..
TESTING
General
The manufacturer shall prepare a programme of type and routine tests and submit these to the
Purchaser at least on month before commencement of the programme.
Each capacitor unit shall be routine tested to IEC 60871-1&2. Type test certification according to
IEC60871-1&2 shall be submitted to the Purchaser for approval. Type test evidence in lieu of tests
shall only be accepted on units of identical construction and similar rating to those proposed for this
application.
Other equipment associated with that capacitor banks shall be subject to routine tests to the relevant
IEC standard.
The complete capacitor sub-bank assembly shall be subject to insulation testing at the factory.
A functional test of the complete capacitor bank control, protection and interlocking schemes shall be
carried out in the factory. These shall include secondary injection tests on the protection relays.
Simulation tests shall be carried out on all control logic for the integrity of the PFC and VC functions.
Routine test results shall be produced and must be available at the time of delivery of the equipment.
Factory Acceptance Tests
CEB reserves the right to witness all Factory Acceptance Tests (FAT, and all costs including travel
board and lodgings for such tests are to be to the Contractor’s account. Notification of the FAT
programme shall be forwarded to CEB at least 2 weeks before the tests.
Site Tests
After the plant and ancillary equipment has been erected and connected on site, the installation
contractor shall, under the supervision of the manufacturer, carry out tests to the satisfaction of CEB.
Details of site tests shall be agreed with CEB, but shall include.
System measurements of harmonics to ensure that the addition of the bank has not affected the
system.
Visual checks of all equipment (for damage, leaks etc).
Earthing, earth switches, door operated earth switches.
a) Continuity of cable connections, ad phasing as appropriate
b) Insulation to earth
c) Insulation between phases
d) Fuse ratings
e) Correct operation of protection relays
f)
Correct operation of controllers
The Site Acceptance Test (SAT) format for the capacitor banks shall be forwarded by the capacitor
bank manufacturer.
DATA SCHEETS
GENERAL
The technical Data Sheets form an integral part of the Tender Documents in connection with the
Project in question, and shall be filled-in as follows :
The CONTRACTOR shall be bound to adhere to the design data and criteria as stated in
these »Technical Data Sheets » or else- where in the Tender Documents.
Only the « Tendered » columns (at the right hand side of the vertical line) of the following pages must
be filled in by the Tenderer, without omission. The manner and breakdown of these pages must not be
changed, i.e. the Tenderer must in no case add something or change something within the
requirements or the « Required » columns. The values stated by the Tenderer shall be guaranteed
limit values, allowing for another margin on its « safe side ».
Each item called for in Technical Data Sheets must be typewritten. If a particular item is not applicable
or not quoted, the letters NA (Not Applicable) or NQ (Not Quoted) shall be typed in the space
provided. For any data not duly inserted in the data sheets, the most unfavourable data stated by any
competitor will be used for evaluation purposes.
If there are deviations from or additions to the Technical Specification and the Technical Data Sheets,
these and any further explanations must be stated on extra sheets only. All these points in which the
Specifications and/or Technical Data Sheets cannot be fulfilled shall be stated and explained
separately, see Section I .
However, whenever the Tenderer is able to offer better values than required, (e.g. for test voltage
levels, ratings at ambient temperature etc.), he is invited to state this without hesitation.
In case expressions « or equivalent », « or similar » etc. are used for manufacturer’s names, these
deviations are understood to come into force only after approval of the EMPLOYER/ENGINEER.
For similar objects like transformers with modified ratio or impedance as well as meters with different
ranges or cables with different cross sections, etc, the Tenderer is requested to multiply the respective
sheets and to enclose them (e.g. as sheet A, B,…). Catalogues and further descriptive information on
all equipment quoted and the pertinent data shall be submitted sufficiently in such a way that the
EMPLOYER/ENGINEER may have full and complete knowledge of the Plant and equipment offered.
These information shall be summarised on suitably arranged sheets, attached to these Technical Data
Sheets, and referring thereto.
REQUIRED
CAPACITOR BANKS
Capacitors
Type
All film
Manufacturer
Standards
IEC 60871-1&2
Rated Current
Unit capacitor
A
Rated voltage
Unit capacitor
kV
Rated output
Unit capacitor
kvar
Nominal capacitance and maximum
permitted tolerance
for each unit capacitor
µF/%
Insulation level of each
Capacitor bank
Lightning impulse
kV
50
Power frequency withstand voltage
kV
125
Maximum ambient temperature
°C
55
Films in elements
Type
Thickness
mm
Number of elements connected in series
and/or parallel per unit capacitor
Number of unit capacitor connected per bank
Impregnating medium
Type
non PCB
Specification Reference
Total losses per kvar
Total weight of complete unit capacitor
Including all fitting and impregnating medium
Kg
TENDERER
REQUIRED
Number of terminals of each unit
Capacitor
creepage distance (indoor installation)
mm/kV
25
creepage distance (outdoor open installation
mm/kV
50
creepage distance (outdoor enclosed installation) mm/kV
25
Time required for capacitor-unit internal
discharge devices alone (without the aid of
external discharge paths) to discharge the
capacitor per phase voltage from rated voltage
to 75 V.
min
max. 10
Type of fuse (internal)
Overall dimensions of unit
height
mm
depth
mm
width
mm
Overall dimensions of bank
height
mm
depth
mm
width
mm
Container
Material
steel + adequate protection
Details of overall finish
(including method of cleaning, primary
and finishing paints)
to be submitted
along with the offer
Circuit breaker
Type
SF6
Manufacturer
Standards
Rated voltage
Switching operations
Inrush current reactors
Supplier / manufacturer
IEC
kV
12
> 10000
TENDERER
Place of manufacture
Place of testing
Standard
IEC 60289
Lightning impulse
kV
125
Rated insulation level at rated voltage
kV
50
Kind of insulation
Dry air core
Rated voltage
kv
Inductance value
µH
Tolerance
+%
Rated continuous current
A
Rated short circuit current
22
As per IEC 60289
Conductor material
Unbalance current transformer
Supplier / manufacturer
Place of manufacture
Place of testing
Standard
IEC 60185
Lightning impulse
kV
125
Rated insulation level at rated voltage
kV
50
Kind of insulation
Dry iron core
Rated voltage
kv
Ratio
A/A
Burden
VA
Accuracy class
22
calculation to be
Submitted
15 mini
1
Over current transformer
Supplier / manufacturer
Place of manufacture
Place of testing
Standard
IEC 60185
Lightning impulse
kV
125
Rated insulation level at rated voltage
kV
50
Kind of insulation
Dry iron core
Rated voltage
kv
Ratio
A/A
100/5
Burden
VA
15 mini
Accuracy class
22
10P10
Over-voltage transformer
Supplier / manufacturer
Place of manufacture
Place of testing
Standard
IEC 60289
Lightning impulse
kV
125
Rated insulation level at rated voltage
kV
50
Kind of insulation
Dry iron core
Rated voltage
kv
Ratio
kV/kV
Burden
VA
Accuracy class
22
22/ 0,11
50 mini
5P
Reactive Power Regulator
Type
numerical
Manufacturer
Description No.
Standards
Rated Current
A
1
Rated frequency
Hz
50
Supply voltage
V DC
Scan Rate
kHz
Regulation steps
110
min 3
Setting Range
cos phi
Memory Capacity
kB RAM
Over Compensation Monitoring
yes
Manual Mode
yes
Self Monitoring
yes
External Interface
RS 232