Download SECTION 16307

SECTION 16307
UNIT SUBSTATION
This Section 16307 has been divided in the following four Sub Sections:
16307-rev0
16307A.
DOUBLE ENDED UNIT SUBSTATIONS WITH 480 V SECONDARY
16307B.
OPEN ENDED UNIT SUBSTATIONS WITH 480 V SECONDARY
16307C.
DOUBLE ENDED UNIT SUBSTATIONS WITH MV SECONDARY
16307D.
OPEN ENDED UNIT SUBSTATIONS WITH MV SECONDARY
(FUTURE)
16307 - 1
December 2004
SECTION 16307A
DOUBLE ENDED UNIT SUBSTATIONS WITH 480 V SEC (Indoor)
1. GENERAL
1A. Manufacturer
Acceptable manufacturers shall be Square D.
1A. Description
Unit Substations shall consist of an integral lineup, from the incoming line terminals to
the outgoing feeder terminals, and shall include:
1B1.
Two Incoming Line Sections
1B2.
Two Transformer Sections
1B3.
Low voltage distribution section as shown on the drawings
1A. Design
Unit substations shall be designed for ease of field assembly and shall be the product
and responsibility of a single manufacturer. See Plan Drawings for dimensional data
on access and limits of operating area.
1. DESIGN AND CONSTRUCTION CRITERIA:
2A. Incoming Line Section
2A1. Each incoming line section shall consist of dead front, completely metal enclosed vertical
section containing one (1) combination load interrupter selector switch, rated 95 kV BIL, 15kV,
600 amperes, 61 kA Asym, consisting of two-position (open/close) fusible, stored energy type,
load interrupter switch in series with a dead break, two position (Line 1/Line 2) cable selector
switch (both manually operated).
2A2. The following features shall be supplied with the switch:
a. High impact viewing windows that permit full view of the position of all switch blades, both
load interrupter and feeder selector switches.
b. The interrupter switch shall be Kirk key interlocked such that:

The interrupter switch must be open before the door can be opened to access any
high voltage live parts or fuses.

The interrupter switch must be open before the feeder selector switch can be
operated.

The door must be close before the interrupter switch can be closed.

Main breaker must be open before the interrupter switch can be operated.
c. A grounded metal barrier in front of every switch to prevent inadvertent contact with any live
part, yet allow for a full-view inspection of the switch blade position.
d. Provision for padlocking the switch in the open or closed position.
e. Permanent “Open-Closed” switch position indicators.
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December 2004
SECTION 16307A
DOUBLE ENDED UNIT SUBSTATIONS WITH 480 V SEC (Indoor)
2A1. Fault protection shall be furnished by three (3) current limiting type fuses in each
incoming section mounted in a separate compartment, within the switch cubicle, accessible
through a hinged door, mechanically interlocked with the interrupter switch; so fuse
compartment is not accessible with the interrupter switch in the closed position.
2A2. Three air gap type lightning arrestors shall be installed in each incoming section between
the fuses and the high voltage terminals of the transformer. These lightning arrestors shall not
be placed inside the transformer compartment and shall be located and installed in such a
manner as to minimize the damage in case of a lightning arrestor explosion.
2A3. In each incoming section provide six (6) high voltage rated copper alloy crimp lugs for
stress cone termination of two three phase 15 kV copper cables, sized as indicated on the
drawings. The cables shall be bottom fed unless otherwise noted on the drawings. Provide
supporting means for incoming 15 kV cables. The supporting means shall be a solid structure
with cable clamps. The cable support structure shall be such that the cables can be adjusted
vertically and/or horizontally.
2A4. All high voltage connections between the switches, transformer and the lightning
arrestors, including the connections for forming the delta, shall be made with silver plated rigid
copper bus supported on porcelain insulators and suitable for a transformer output of 3333 kVA.
All bolts shall be Grade 5 with Belleville type spring washers.
2A5. A silver plated copper ground bus shall be provided in each incoming section and directly
fastened to the bare metal surface of the vertical section. The ground bus shall be located at
the bottom of the enclosure as near to the door opening as practical and functional. The ground
bus shall be exposed and readily accessible and located such as to prevent inadvertent contact
with the live parts while attaching ground cable clamps or a high voltage meter.
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16307A - 3
December 2004
SECTION 16307A
DOUBLE ENDED UNIT SUBSTATIONS WITH 480 V SEC (Indoor)
2A. Transformer Section
2B1.
General:
a. A three phase, dry type, power cast coil copper winding transformer shall be provided in
each transformer section.
b. These transformers will be used to supply a three phase, four wire Wye connected low
voltage distribution system from three phase, three wire Delta high voltage feeders.
c. Characteristics, definition and terminology, except as specifically covered in this
Specification, shall be in accordance with the latest revision of the standards of American
National Standards Institute and the National Electrical Manufacturer’s Association.
2B1.
Ratings: High and Low Voltage Ratings shall be as follows:
d. Self cooled rating
As specified on the drawings
e. Fan cooled rating
133% of self cooled rating
f.
Frequency
60 Hertz
g. Number of phases
3
h. Primary Voltage
12.47 kV
i.
Secondary Voltage
j.
BIL of Coils:
k. Connections:
l.
Impedance
277/480 Volts
Primary
Secondary
95 kV
10 kV
Primary
Delta
Secondary
Wye
Secondary voltage lags Primary voltage by 30 deg.
Shall meet ANSI C57.12 Table 10 Requirement
m. Sound level at self cooled rating 63 Decibels
n. Insulation system
185 Deg. C
o. Temperature rise
80 Deg. C
2B1.
Taps
p. In addition to the rated voltage tap, the Transformers shall be provided with four (4) taps,
which are 2 ½ % of full rated voltage. Two (2) of these shall be above the primary rated voltage,
and two shall be below the primary rated voltage. Each shall be brought to an internal terminal,
accessible through a removable cover section. Taps shall be changed only when the
transformer is de-energized.
q. Taps shall be set to the rated voltage position before shipment. Suitable connection links
shall be provided for tap changing. Each tap position and the tap numbers shall be clearly
shown.
2B1.
Ancillary Devices and Features
Transformer sections are to contain the following features:
r.
Removable side panels with handles
s. Ground Pad
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December 2004
SECTION 16307A
DOUBLE ENDED UNIT SUBSTATIONS WITH 480 V SEC (Indoor)
t.
Nameplate
u. Provision for jacking or lifting
v. Cooling fans or blowers with air ducts, including automatic control, temperature indication,
alarm contacts and wiring. Direction of air flow shall be upwards. Fans shall be heavy duty,
squirrel cage type mounted on the enclosure frame (not on the transformer) with ducting
provided as necessary to cool the transformer core. All fan and motor bearings shall be sealed
type. The cooling system shall be 100% redundant so that the transformer can deliver its full FA
rated power in spite of a complete failure of one set of cooling system.
w. Transformer fans shall be automatically controlled, by sensor imbedded in winding, with
selector switch for “Manual-Off-Auto” operation and three pilot lights; Power Available, Fan
Running, Excess Temperature.
2B1. Transformer enclosures shall be large enough to accommodate a 2500/3333 kVA,
AA/FA, 95 kV BIL transformer. They shall have removable, sheet metal top cover and side
panels secured to a rigid self supporting steel frame so that the enclosure will not collapse when
panels are removed. The bolts securing the removable panels to the frame shall engage into a
minimum of five threads in the frame. Bolts fastened to the frame by sheet metal hardware are
not acceptable. A minimum of two handles shall be provided on each removable panel to
facilitate removal and installation. Handles shall be of sufficient size, smooth and with no sharp
edges or corners. No fan control or other wiring shall be secured to the removable panels.
2C.
Low Voltage Distribution Section
2C1.
General:
x. The low voltage, metal enclosed power assembly shall consist of a stationary structure
assembly: one or more removable air circuit breaker units fitted with disconnecting devices; and
other necessary equipment. The switch gear shall be suitable for 600 V maximum service and
shall receive a dielectric test, for that voltage class, in accordance with NEMA standards.
y. The low voltage section shall consist of five vertical sections as follows unless specified
differently in the purchase order:
The section 1 shall be composed of three compartments with compartment 1A for metering and
auxiliary power, compartment 1B for Main 1 breaker, and compartment 1C having space for a
future 1600A feeder breaker.
Section 2 shall have four 800A feeder breakers.
Section 3 shall be composed of three compartments with compartment 3A for metering,
compartment 3B for bus tie breaker, and compartment 3C having space for special tools
instruction books etc.
Section 4 shall be a mirror image of Section 2.
Section 5 shall be a mirror image of Section 1 and shall accommodate Main 2 breaker in
compartment 5B.
z. The structure shall be so designed that future additions may be readily made. The steel
structure shall be thoroughly cleaned and phosphatized, prior to application of the priming and
finishing coats of paint. An insulated barrier shall be provided between each main breaker
section and the adjacent distribution section. An insulating barrier shall also be provided
between the bus tie breaker and each adjacent distribution section. These barriers shall be
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December 2004
SECTION 16307A
DOUBLE ENDED UNIT SUBSTATIONS WITH 480 V SEC (Indoor)
such that workers on one side of the barrier are not exposed to live parts on the same or other
side of the barrier.
aa. A control power transformer, (with primary disconnect and secondary fuses) 480 to 120/240
Volts, sized to operate cooling fans and electrically operated breakers shall be provided for each
half of the double ended substation. This control power transformer shall not be used for
metering.
bb. The rear of the low voltage section shall be constructed with hinged doors secured with
knurled screw fittings, which can be opened without the use of tools, giving access to the bus
and feeders.
cc. Each outgoing LV feeder shall be wired up to a junction box with terminal blocks on top of
the Unit Substation such that the feeder cables can be conveniently terminated or removed
without opening the rear panel of the vertical section or switching off other feeders. Several
feeders can share a common junction box with rigid barriers between adjacent compartments
with separate covers such that work on any feeder shall not expose the worker to the live parts
of any other feeder. Three phase, one neutral and a ground terminal of appropriate size marked
P1, P2, P3, N and G shall be provided for each feeder. Care must be exercised that the phase
terminals are connected to the same phase as marked. The terminals shall be arranged in a
logical sequence such that the same phase is in the same location in each junction box or
compartment.
The above requirement can be waived only with the approval of HITACHI’s Electrical Engineer
and the Maintenance contractor’s System Electrical Engineer. In this case support structures
with adjustable cable clamps shall be provided to secure secondary feeder cables. Sufficient
space shall be provided for the bending radius of the cables.
2C1.
Bus Structure:
dd. The Unit Substation bus structure shall be copper of sufficient size to limit temperature rise
to 65 Degrees C, based on UL tests, and shall be mounted on insulator supports of high impact,
non tracking insulating materials. The bus shall be rated for a transformer output of 3333 kVA.
The entire bus structure shall be braced to withstand 85,000 Amps RMS symmetrical short
circuit. All bolts shall be Grade 5 with Belleville type spring washers.
ee. A continuous 100% neutral bus in the Unit Substation shall be provided.
ff. A continuous 25% ground bus in the Unit Substation shall be provided.
gg. A readily accessible and removable buss link in the neutral buss shall be provided.
2C1.
Circuit Breakers:
hh. General - All Breakers
1) The circuit breakers shall be Square D draw out type DS air circuit breakers or equivalent,
three pole, 480 Volt. The interrupting rating shall be a minimum of 65 kA sym. The current
rating shall be as indicated on the drawings. These breakers shall incorporate specifically
designed circuit interrupting devices which provide high interrupting efficiency and minimize
formation of arc, flame and gases.
2) The air circuit breakers shall have silver tungsten butt type contacts which operate under
high pressure. The arcing contacts shall be arc resisting silver tungsten. The breaker shall be
equipped with arc chutes, which effectively enclose the arcing contacts and continue the arc to
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December 2004
SECTION 16307A
DOUBLE ENDED UNIT SUBSTATIONS WITH 480 V SEC (Indoor)
reduce the disturbance caused by short circuit interruption. Each breaker shall be equipped
with a position indicator mechanically connected to the circuit breaker mechanism.
3) All circuit breakers shall be equipped with a Square D Digitrip 610 solid state trip unit. The
adjustments shall be as follows:
ii. With long time pick up delay, short time pick up delay, ground pick up delay, and target
annunciation with manual reset.
iii. Ground fault: 5 - 60 Amp pick up at 0 - 1 S.
1) All feeder breakers rated 1600 amperes or less shall be manually operated.
2) Main Breaker
The main breaker shall be rated 4,000 Amps.
A Kirk key interlock shall be provided for the main breaker and arranged so that the main circuit
breaker must be opened before the high voltage interrupter switch is operated.
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December 2004
SECTION 16307A
DOUBLE ENDED UNIT SUBSTATIONS WITH 480 V SEC (Indoor)
3) Tie breaker
Provide a Tie Breaker rated 4000 Amps. Provision shall also be made for the future installation
of a Kirk key interlock on the tie breaker.
4) Six (6) copies of complete operating and maintenance manuals including tripping curves
shall be provided.
5) Acceptance tests as approved by buyer and start up service shall be provided at the site by
the vendor. Testing shall include the load interrupter switch, cable selector switch, transformer
and all secondary main, tie and feeder breakers. Breakers shall be tested according to trip
settings provided by the buyer.
6) Unit Substation warranty/guarantee (minimum of one year from date of installation), covering
workmanship and functional performance shall be provided.
7) Breaker Hoist Assembly and brackets necessary for lifting of breakers and any tools
required for racking breakers in or out shall be provided.
2C1.
Stored Energy Mechanism:
ii. Electrically operated and manually operated breakers shall have stored energy operating
mechanisms. One stroke of the operating handle shall charge the stored energy spring, when
operating the manual breaker. The release of the energy to close the breaker manually, shall
be by means of a mechanical push button, which ensures positive control of the closing
operation. Electrical close shall be initiated by means of a release solenoid.
jj. It shall be possible to test and calibrate the time and current characteristics and trip circuit,
by means of a portable, plug in test device. A trip unit testing device shall be provided.
2C1.
Instrumentation:
kk. Each low voltage main circuit breaker shall be provided with a metering compartment. This
metering compartment shall have provisions for remote indication of all functions and contain
the following switchboard type equipment:
1) One (1) Ammeter capable of recording maximum and/or peak demand with a manual reset.
2) One (1) Ammeter Switch, four (4) position.
3) One (1) Voltmeter, AC indicating type, 250 degree scale.
4) One (1) Voltmeter Switch, seven position.
5) Three (3) current transformers, three (3) potential transformers and one (1) control power
transformer with proper fusing (Primary and secondary).
6) One (1) set of potential and current test blocks and plugs.
7) One (1) kilowatt transducer with 4-20 milliamp output:
Scientific Columbus 2 ½ element, Cat. No. XL31K52 1/2P-A7. The transducer shall be wired in
such a way that it can be removed safely for calibration without shutdown of the unit substation.
ll. Each low voltage feeder breaker and the bus tie breaker shall be provided with one (1)
Ammeter capable of recording maximum and/or peak demand with a manual reset.
mm.All current terminal blocks shall be short circuiting type.
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December 2004
SECTION 16307A
DOUBLE ENDED UNIT SUBSTATIONS WITH 480 V SEC (Indoor)
1. TESTING
3A. Unit Substation - General
3A1.
Four (4) sets of certified factory test reports performed in accordance with the latest
revised standards of IEEE, ANSI and NEMA shall be provided.
3A2.
Breakers shall be tested with Primary Injection at the factory and their test reports
submitted.
3A3.
Breakers shall be tested, calibrated, and the trip settings set on site by the vendor
representative per recommendation of the Electrical Systems Engineer.
3B. Transformer
3B1.
Four (4) sets of certified factory test report shall include the following information:
a. Applicable outline and nameplate drawing.
b. Design and actual noise level tests.
c. BIL impulse verification test.
d. Percent impedance.
e. Percent regulation at 0.8 power factor.
f. Load loss. Reference temperature shall be based on actual temperature of each winding
plus 20 Degrees C.
g. Core Loss.
h. Percent excitation current.
***END OF SECTION 16307A***
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December 2004
SECTION 16307B
OPEN ENDED UNIT SUBSTATIONS WITH 480 V SEC (Indoor)
1. GENERAL
1A. Manufacturer
Acceptable manufacturers shall be Square D.
1A. Description
Unit Substations shall consist of an integral lineup, from the incoming line terminals to
the outgoing feeder terminals, and shall include:
1B1.
Incoming Line Section
1B2.
Transformer Section
1B3.
Low voltage distribution section as shown on the drawings
1A. Design
Unit substations shall be designed for ease of field assembly and shall be the product
and responsibility of a single manufacturer. See Plan Drawings for dimensional data
on access and limits of operating area.
1. DESIGN AND CONSTRUCTION CRITERIA:
2A. Incoming Line Section
2A1. Incoming line section shall consist of dead front, completely metal enclosed vertical
section containing one (1) combination load interrupter selector switch, rated 95 kV BIL, 15kV,
600 amperes, 61 kA Asym, consisting of two-position (open/close) fusible, stored energy type,
load interrupter switch in series with a dead break, two position (Line 1/Line 2) cable selector
switch (both manually operated).
2A2. The following features shall be supplied with the switch:
a. High impact viewing windows that permit full view of the position of all switch blades, both
load interrupter and feeder selector switches.
b. The interrupter switch shall be Kirk key interlocked such that:

The interrupter switch must be open before the door can be opened to access any
high voltage live parts or fuses.

The interrupter switch must be open before the feeder selector switch can be
operated.

The door must be close before the interrupter switch can be closed.

Main breaker must be open before the interrupter switch can be operated.
c. A grounded metal barrier in front of every switch to prevent inadvertent contact with any live
part, yet allow for a full-view inspection of the switch blade position.
d. Provision for padlocking the switch in the open position.
16307B-rev0
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December 2004
SECTION 16307B
OPEN ENDED UNIT SUBSTATIONS WITH 480 V SEC (Indoor)
e. Permanent “Open-Closed” switch position indicators.
2A1. Fault protection shall be furnished by three (3) current limiting type fuses mounted in a
separate compartment, within the switch cubicle, accessible through a hinged door,
mechanically interlocked with the interrupter switch; so fuse compartment is not accessible with
the interrupter switch in the closed position.
2A2. Three air gap type lightning arrestors shall be installed between the fuses and the high
voltage terminals of the transformer. These lightning arrestors shall not be placed inside the
transformer compartment and shall be located and installed in such a manner as to minimize
the damage in case of a lightning arrestor explosion.
2A3. Provide six (6) high voltage rated copper alloy crimp lugs for stress cone termination of
two three phase 15 kV copper cables, sized as indicated on the drawings. The cables shall be
bottom fed unless otherwise noted on the drawings. Provide supporting means for incoming 15
kV cables. The supporting means shall be a solid structure with cable clamps. The cable
support structure shall be such that the cables can be adjusted vertically and/or horizontally.
2A4. All high voltage connections between the switches, transformer and the lightning
arrestors, including the connections for forming the delta, shall be made with silver plated rigid
copper bus supported on porcelain insulators and suitable for a transformer output of 3333 kVA.
All bolts shall be Grade 5 with Belleville type spring washers.
2A5. A silver plated copper ground bus shall be provided and directly fastened to the bare
metal surface of the vertical section. The ground bus shall be located at the bottom of the
enclosure as near to the door opening as practical and functional. The ground buss shall be
exposed and readily accessible and located such as to prevent inadvertent contact with the live
parts while attaching ground cable clamps or a high voltage meter.
16307B-rev0
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December 2004
SECTION 16307B
OPEN ENDED UNIT SUBSTATIONS WITH 480 V SEC (Indoor)
2A. Transformer Section
2B1.
General:
a. A three phase, dry type, powercast coil copper winding transformer shall be provided in the
transformer section.
b. The transformer will be used to supply a three phase, four wire Wye connected low voltage
distribution system from three phase, three wire Delta high voltage feeders.
c. Characteristics, definition and terminology, except as specifically covered in this
Specification, shall be in accordance with the latest revision of the standards of American
National Standards Institute and the National Electrical Manufacturer’s Association.
2B1.
Ratings: High and Low Voltage Ratings shall be as follows:
d. Self cooled rating
As specified on the drawings
e. Fan cooled rating
133% of self cooled rating
f.
Frequency
60 Hertz
g. Number of phases
3
h. Primary Voltage
12.47 kV
i.
Secondary Voltage
j.
BIL of Coils:
k. Connections:
l.
Impedance
277/480 Volts
Primary
Secondary
Primary
Delta
Secondary
Star
Secondary voltage lags Primary voltage by 30 deg.
To meet ANSI C57.12 Table 10
m. Sound level at self cooled rating
63 Decibels
n. Insulation system
185 Deg. C
o. Temperature rise
80 Deg. C
2B1.
95 kV
10 kV
Taps
p. In addition to the rated voltage tap, the Transformers shall be provided with four (4) taps,
which are 2 ½ % of full rated voltage. Two (2) of these shall be above the primary rated voltage,
and two shall be below the primary rated voltage. Each shall be brought to an internal terminal,
accessible through a removable cover section. Taps shall be changed only when the
transformer is de-energized.
q. Taps shall be set to the full voltage position before shipment. Suitable connection links shall
be provided for tap changing. Each tap position and the tap numbers shall be clearly shown.
2B1.
Ancillary Devices and Features
Transformer sections are to contain the following features:
r.
Removable side panels with handles
s. Ground Pad
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December 2004
SECTION 16307B
OPEN ENDED UNIT SUBSTATIONS WITH 480 V SEC (Indoor)
t.
Nameplate
u. Provision for jacking or lifting
v. Cooling fans or blowers with air ducts, including automatic control, temperature indication,
alarm contacts and wiring. Direction of air flow shall be upwards. Fans shall be heavy duty,
squirrel cage type mounted on the enclosure frame (not on the transformer) with ducting
provided as necessary to cool the transformer core. All fan and motor bearings shall be sealed
type. The cooling system shall be 100% redundant so that the transformer can deliver its full FA
rated power in spite of a complete failure of one set of cooling system.
w. Transformer fans shall be automatically controlled, by sensor imbedded in winding, with
selector switch for “Manual-Off-Auto” operation and three pilot lights; Power Available, Fan
Running, Excess Temperature.
2B1. Transformer enclosure shall be large enough to accommodate a 2500/3333 kVA, AA/FA,
95 kV BIL transformer. It shall have removable panels secured to a rigid self supporting steel
frame so that the enclosure will not collapse when panels are removed. The bolts securing the
removable panels to the frame shall engage into a minimum of five threads in the frame with no
exception. A minimum of two handles shall be provided on each removable panel to facilitate
removal and installation. Handles shall be of sufficient size, smooth and with no sharp edges or
corners. No fan control or other wiring shall be secured to the removable panels.
2C.
Low Voltage Distribution Section
2C1.
General:
x. The low voltage, metal enclosed power assembly shall consist of a stationary structure
assembly: one or more removable air circuit breaker units fitted with disconnecting devices; and
other necessary equipment. The switch gear shall be suitable for 600 V maximum service and
shall receive a dielectric test, for that voltage class, in accordance with NEMA standards.
y. The structure shall be so designed that future additions may be readily made. The steel
structure shall be thoroughly cleaned and phosphatized , prior to application of the priming and
finishing coats of paint. An insulated barrier shall be provided between the main breaker section
and the distribution section.
z. A control power transformer, (with primary disconnect and secondary fuses) 480 to 120/240
Volts, sized to operate cooling fans and electrically operated breakers shall be provided. This
control power transformer shall not be used for metering.
aa. The rear of the low voltage section shall be constructed with hinged doors secured with
knurled screw fittings, which can be opened without the use of tools, giving access to the bus
and feeders.
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December 2004
SECTION 16307B
OPEN ENDED UNIT SUBSTATIONS WITH 480 V SEC (Indoor)
bb. Each outgoing LV feeder shall be wired up to a junction box with terminal blocks on top of
the Unit Substation such that the feeder cables can be conveniently terminated or removed
without opening the rear panel of the vertical section or switching off other feeders. Several
feeders can share a common junction box with rigid barriers between adjacent compartments
with separate covers such that work on any feeder shall not expose the worker to the live
terminals of any other feeder. Three phase, one neutral and a ground terminal of appropriate
size marked P1, P2, P3, N and G shall be provided for each feeder. Care must be exercised
that the phase terminals are connected to the same phase as marked. The terminals shall be
arranged in a logical sequence such that the same phase is in the same location in each
junction box or compartment.
The above requirement can be waived only with the approval of HITACHI’s Electrical Engineer
and the Maintenance contractor’s System Electrical Engineer. In this case support structures
with adjustable cable clamps shall be provided to secure secondary feeder cables. Sufficient
space shall be provided for the bending radius of the cables.
2C1.
Bus Structure:
cc. The Unit Substation bus structure shall be copper of sufficient size to limit temperature rise
to 65 Degrees C, based on UL tests, and shall be mounted on insulator supports of high impact,
non tracking insulating materials. The bus shall be rated for a transformer output of 3333 kVA.
The entire bus structure shall be braced to withstand 85,000 Amps RMS symmetrical short
circuit. All bolts shall be Grade 5 with Belleville type spring washers.
dd. A continuous 100% neutral bus in the Unit Substation shall be provided.
ee. A continuous 25% ground bus in the Unit Substation shall be provided.
ff. A readily accessible and removable buss link in the neutral buss shall be provided.
2C1.
Circuit Breakers:
gg. General - All Breakers
1) The circuit breakers shall be Square D draw out type DS air circuit breakers or equivalent,
three pole, 480 Volt. The interrupting rating shall be a minimum of 65 kA sym. The current
rating shall be as indicated on the drawings. These breakers shall incorporate specifically
designed circuit interrupting devices which provide high interrupting efficiency and minimize
formation of arc, flame and gases.
2) The air circuit breakers shall have silver tungsten butt type contacts which operate under
high pressure. The arcing contacts shall be arc resisting silver tungsten. The breaker shall be
equipped with arc chutes, which effectively enclose the arcing contacts and continue the arc to
reduce the disturbance caused by short circuit interruption. Each breaker shall be equipped
with a position indicator mechanically connected to the circuit breaker mechanism.
3) All circuit breakers shall be equipped with a square D Digitrip 610 solid state trip unit. The
adjustments shall be as follows:
ii. With long time pick up delay, short time pick up delay, ground pick up delay, and target
annunciation with manual reset.
iii. Ground fault: 5 - 60 Amp pick up at 0 - 1 S.
1) All feeder breakers rated 1600 amperes or less shall be manually operated.
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December 2004
SECTION 16307B
OPEN ENDED UNIT SUBSTATIONS WITH 480 V SEC (Indoor)
2) Main Breaker
The main breaker shall be rated 4,000 Amps.
A Kirk key interlock shall be provided for the main breaker and arranged so that the main circuit
breaker must be opened before the high voltage interrupter switch is operated.
3) Tie breaker
Provide a Tie Breaker rated 4000 Amps. This Tie breaker will be used in future for connecting
this Unit Substation to another Unit Substation through 6x500 kcmil per phase or neutral single
conductor THWN top entry copper cables. Provision shall also be made for a ground
connection with 2x500 kcm single conductor copper cables. Proper lugs with nuts and bolts
shall be provided for connecting the cables. Provision shall also be made for the future
installation of a Kirk key interlock on the tie breaker.
The load side terminals of the Bus Tie Breaker shall be bussed up to a junction box with
terminal blocks on top of the Unit Substation such that the outgoing cables can be conveniently
terminated or removed without opening the rear panel of the vertical section or switching off
other feeders. The junction box shall be so arranged that work on tie feeder cables shall not
expose the worker to the live terminals of any other feeder. Three phase, one neutral and a
ground terminal of appropriate size marked P1, P2, P3, N and G shall be provided for the tie
feeder. Care must be excised that the phase terminals are connected to the same phase as
marked. The terminals shall be arranged in a sequence such that the same phase is in the
same location as for the feeder junction box or compartment.
The above requirement can be waived only with the approval of HITACHI’s Electrical Engineer
and the Maintenance contractor’s System Electrical Engineer. In this case support structures
with adjustable cable clamps shall be provided to secure tie feeder cables. Sufficient space
shall be provided for the bending radius of the cables.
4) Six (6) copies of complete operating and maintenance manuals including tripping curves
shall be provided.
5) Acceptance tests as approved by buyer and start up service shall be provided at the site by
the vendor. Testing shall include the load interrupter switch, cable selector switch, transformer
and all secondary main, tie and feeder breakers PT's and CT's. Breakers shall be tested
according to trip settings provided by the buyer.
6) Unit Substation warranty/guarantee (minimum of one year from date of installation), covering
workmanship and functional performance shall be provided.
7) Breaker Hoist Assembly and brackets necessary for lifting of breakers and any tools
required for racking breakers in or out shall be provided.
2C1.
Stored Energy Mechanism:
hh. Electrically operated and manually operated breakers shall have stored energy operating
mechanisms. One stroke of the operating handle shall charge the stored energy spring, when
operating the manual breaker. The release of the energy to close the breaker manually, shall
be by means of a mechanical push button, which ensures positive control of the closing
operation. Electrical close shall be initiated by means of a release solenoid.
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SECTION 16307B
OPEN ENDED UNIT SUBSTATIONS WITH 480 V SEC (Indoor)
ii. It shall be possible to test and calibrate the time and current characteristics and trip circuit,
by means of a portable, plug in test device. A trip unit testing device shall be provided.
2C1.
Instrumentation:
jj. The low voltage main circuit breaker shall be provided with a metering compartment. This
metering compartment shall have provisions for remote indication of all functions and contain
the following switchboard type equipment:
1) One (1) Ammeter capable of recording maximum and/or peak demand with a manual reset.
2) One (1) Ammeter Switch, four (4) position.
3) One (1) Voltmeter, AC indicating type, 250 degree scale.
4) One (1) Voltmeter Switch, seven position.
5) Three (3) current transformers, three (3) potential transformers and one (1) control power
transformer with proper fusing (Primary and secondary).
6) One (1) set of potential and current test blocks and plugs.
7) One (1) kilowatt transducer with 4-20 milliamp output:
Scientific Columbus 2 ½ element, Cat. No. XL31K52 1/2P-A7. The transducer shall be wired in
such a way that it can be removed safely for calibration without shutdown of the unit substation.
kk. Each low voltage feeder breaker and the bus tie breaker shall be provided with one (1)
Ammeter capable of recording maximum and/or peak demand with a manual reset.
ll. All current terminal blocks shall be short circuiting type.
1. TESTING
3A. Unit Substation - General
3A1.
Four (4) sets of certified factory test reports performed in accordance with the latest
revised standards of IEEE, ANSI and NEMA shall be provided.
3A2.
Breakers shall be tested with Primary Injection at the factory and their test reports
submitted.
3A3.
Breakers shall be tested, calibrated, and the trip settings set on site by the vendor
representative per recommendation of the Electrical Systems Engineer.
3B. Transformer
3B1.
Four (4) sets of certified factory test report shall include the following information:
a. Applicable outline and nameplate drawing.
b. Design and actual noise level tests.
c. BIL impulse verification test.
d. Percent impedance.
e. Percent regulation at 0.8 power factor.
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SECTION 16307B
OPEN ENDED UNIT SUBSTATIONS WITH 480 V SEC (Indoor)
f. Load loss. Reference temperature shall be based on actual temperature of each winding
plus 20 Degrees C.
g. Core Loss.
h. Percent excitation current.
***END OF SECTION 16307B***
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SECTION 16307C
DOUBLE ENDED UNIT SUBSTATIONS WITH MV SEC (Indoor)
(FUTURE)
***END OF SECTION 16307C***
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December 2004
SECTION 16307D
OPEN ENDED UNIT SUBSTATIONS WITH MV SEC (Indoor)
(FUTURE)
***END OF SECTION 16307D***
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December 2004