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PART 1- GENERAL
1.1 DESCRIPTION
A. This specification covers the requirements for solid dielectric, load break switches and fault
interrupters for distribution systems through 27kV. They shall be manufactured by G&W
Electric Co. and designated as Trident® Series.
1.2 QUALITY ASSURANCE
A. Manufacturer Qualifications: The chosen manufacturer shall have at least 20 years
experience in manufacturing SF6 insulated medium voltage switchgear. The manufacturer
of the switches shall be completely and solely responsible for the performance of the load
break switch and fault interrupter as well as the complete integrated assembly as rated.
B. The manufacturer shall furnish certification of ratings of the load break switch, fault
interrupter and the integrated switch assembly upon request.
C. The switch shall comply with requirements of the latest revisions of applicable industry
standards, including:
(a) IEEE C37.71, IEEE C37.72, IEEE C37.74, IEEE C37.60, ANSI/IEEE 386, IEC
60265-1
D. The switch manufacturer shall be ISO 9001:2000 and ISO 14001:2004 certified.
1.3 DELIVERY, STORAGE, AND HANDLING
A. Load break switches and fault interrupters shall be shipped preassembled at the factory.
No field assembly shall be required.
B. The contractor, if applicable, shall handle, transfer and move the switches in accordance
with manufacturer’s recommendations.
PART 2- PRODUCTS
2.1 SWITCH CONFIGURATION
A. Switches shall be Padmount style with mild steel enclosure; Padmount style with
stainless steel enclosure; Vault style, nonsubmersible control enclosures, if required; or
Vault style, submersible control enclosures, if required, as indicated on the one-line
diagram.
B. Two-Way (using one module) shall consist of single phase, load break; single phase, fault
interrupter; three phase, load break; or three phase, fault interrupter, as indicated on the
one-line diagram.
C. Multi-Way (using two through six modules) shall consist of three phase load break
modules and three phase fault interrupter modules, as indicated on the one-line diagram.
2.2 SWITCH CONSTRUCTION
A. General
Assembly shall be a deadfront design. The operating mechanism housing shall be
stainless steel with a viewing window for verification of contact position. The housing shall
be painted ANSI 70 light gray using corrosion-resistant epoxy paint. Operating handles
shall be padlockable and adaptable to keylock schemes. The operating shaft shall be
stainless steel providing maximum corrosion resistance. A double “O” ring shaft seal shall
be used for a leak resistant, long life seal.
B. Load Break Switches
The load break switch shall consist of vacuum bottle(s) encapsulated within solid dielectric
epoxy modules with spring-assisted operating mechanism. For three phase switches the
mechanism shall consist of three vacuum bottles mechanically linked to a single, spring-
assisted operating mechanism. The operating mechanism shall be actuated from outside
the mechanism housing.
C. Fused Load Break Switches
The fused load break switch shall consist of a load break switch (described above) with
provisions for elbow mounted encapsulated fuses. Parking stands shall be available as an
accessory. An optional interlock shall be available to prevent access to the fuses unless
the switch is open. Fuses shall be current limiting with epoxy insulation and an integral
600A elbow (T body) connector for connection to the switch. The load side of the fuse shall
be either a 200A deepwell or 600A apparatus ANSI/IEEE 386 separable connector
interface.
D. Fault Interrupter
The fault interrupter shall consist of vacuum bottle(s) and internal current transformer(s)
encapsulated within solid dielectric epoxy modules with spring-assisted operating
mechanism. For three phase interrupters, the mechanism shall consist of three vacuum
bottles mechanically linked to a single spring-assisted operating mechanism. Electrical
opening shall be by a solenoid that is activated from an interrupter relay. Closing (reset) of
the interrupter shall be mechanical with the use of an operating mechanism actuated from
outside the mechanism housing. The mechanical linkage assembly shall provide for a “trip-
free” operation which allows the fault interrupter to operate independent of the operating
handle.
2.3 DESIGN RATINGS
A. Load Break Switches
The switch shall be rated (choose appropriate column):
SELECTION OF RATINGS |
IEEE/IEC |
Voltage Class, kV |
15 |
25 |
Maximum Design Voltage, kV |
15.5 |
27 |
Impulse Level (BIL) Voltage, kV |
110 |
125 |
Continuous Current, Amperes |
630 |
630 |
Load break Current, Amperes |
630 |
630 |
One Minute Withstand (dry), AC kV |
35 |
60 |
Production Test Rating |
34 |
40 |
15 Minute Withstand, DC kV |
53 |
78 |
Momentary Current, kA, ASYM |
20 |
20 |
Fault-Close Current, kA, ASYM |
20 |
20 |
One Second Current, kA, SYM |
12.5 |
12.5 |
Mechanical Endurance, Operations |
2000 |
2000 |
B. Fault Interrupters
The fault interrupter shall be rated (choose appropriate column):
SELECTION OF RATINGS |
IEEE/IEC |
Voltage Class, kV |
15 |
25 |
Maximum Design Voltage, kV |
15.5 |
27 |
Impulse Level (BIL) Voltage, kV |
110 |
125 |
Continuous Current, Amperes |
630 |
630 |
Load break Current, Amperes |
630 |
630 |
One Minute Withstand (dry), AC kV |
35 |
60 |
Production Test Rating |
34 |
40 |
Symmetrical Interrupting Rating, kA |
12.5 |
12.5 |
Asymmetrical Interrupting Rating, kA |
20 |
20 |
Fault-Close Current, kA, SYM |
12.5 |
12.5 |
Mechanical Operations |
2000 |
2000 |
C. Fuses
The fuses shall be rated:
SELECTION OF RATINGS |
IEEE/IEC |
Nominal Voltage, kV, Gnd-Y
Impulse Level (BIL) Voltage, kV |
8.7/15
95 |
15/25
125 |
Continuous Current, Amperes
Load break Current, Amperes
One Minute AC Withstand, kV
Fifteen Minute DC Withstand, kV
Interrupting, Amperes, RMS, SYM |
10-140
630
34
53
50k |
10-25
630
40
78
50k |
ANSI C37.60 Fault Interrupting Duty
Percent of Maximum:
Interrupting Rating |
Approx. Interrupting:
Current Amps |
No. of Fault:
Interruptions |
15-20% |
2000 |
44 |
45-55% |
6000 |
56 |
90-100% |
12000 |
16 |
Total Number of Fault Interruptions: 116 |
2.4 BUSHINGS
A. Two-Way (using one module)
Bushings shall be integral to the switch module and designed and tested to IEEE 386.
Bushings closest to the operating mechanism shall be 600 or 200 amp and bushings away
from the operating mechanism shall be either 600 or 200 amp, as indicated on the switch
drawing.
B. Multi-Way (two through six modules)
Bushings shall be designed and tested to IEEE 386. Bushings shall be 600 amp or 200
amp, as indicated on the switch drawing.
2.5 FAULT INTERRUPTER RELAY
For fault interrupters, a relay shall monitor the current on each phase using the integral
encapsulated current transformer(s). The relay shall compare currents on each phase of the
load circuits with pre-selected time current curves and cause the fault interrupters to interrupt the
current at the appropriate time. The relay shall be powered from the current transformers molded
into the epoxy encapsulation. No external power source shall be required for protection.
2.6 PADMOUNT ENCLOSURE (if applicable)
Enclosures shall be made of 12 gauge mild or stainless steel and manufactured to ANSI C37.72
and C57.12.28 standards. The enclosure shall be mounted independently to allow for easy
removal for cable installation or future replacement. Enclosures shall be tamper-resistant
incorporating hinged access door(s) with pentahead locking bolt(s) and provisions for
padlocking. The enclosure shall be provided with lifting provisions and painted with a Munsell
7.0GY3.29/1.5 green finish.
2.7 FACTORY PRODUCTION TESTS
Each assembly shall undergo a mechanical operations check, a one minute phase-to-phase,
phase-to-ground and across the open contact AC hi-pot test. Circuit resistance shall be
checked on all ways. Each module shall undergo an X-ray inspection and a partial discharge
test to ensure void-free construction.
2.8 STANDARD COMPONENTS
The following shall be included as standard:
- Welded stainless steel mechanism housing painted light gray with stainless steel and brass fasteners.
- Lifting provisions.
- Corrosion-resistant nameplates and line diagram.
- Switch operating mechanism(s) with padlock provision and single keylock provision.
- Mounting provisions.
- Ground provisions (1/2-13 threaded boss).
- For padmount switches: Padmount enclosure (see section 8).
2.9 OPTIONS (included in catalog number)
The following options shall be supplied: (check as appropriate)
- ____ Auxiliary contacts installed on spring operating mechanism.
- ____ Stationary mounted motor actuator with auxiliary contacts installed on spring operating mechanism.
- ____ Single way, stationary motor control.
- ____ Multi-way, stationary motor control (not available on two way switches).
- ____ Type 1 interrupter relay.
- ____ Type 2 interrupter relay.
- ____ Type 3 interrupter relay.
- ____ Type 4 interrupter relay.
- ____ Provision for Type 5 interrupter relay.
- ____ Type 6 interrupter relay.
- ____ Type 7 interrupter relay.
2.10 ACCESSORIES (additional items)
The following accessories shall be supplied: (check all that apply)
- ____ 4/0 brass ground lug(s).
- ____ Portable motor control.
- ____ Remote terminal units.
- ____ Junction box for connection of remote power/remote trip or auxiliary contacts.
- ____ Digital voltage sensors.
- ____ Galvanized frame (24” high bushing height)
- ____ Laptop programming kit for Types 3, 4 and 7 relays.
- ____ Parking stands for each phase.
- ____ Type 5 oil fuse cutout interrupter relay.
- ____ Removable operating handle.
2.11 LABELING
A. Hazard Alerting Signs
The exterior of the padmounted enclosure (if furnished) shall be provided with “Warning--
Keep Out--Hazardous Voltage Inside--Can Shock, Burn, or Cause Death” signs. Each unit
of switchgear shall be provided with a “Danger--Hazardous Voltage--Failure to Follow These Instructions Will Likely Cause Shock, Burns, or Death” sign. The text shall further indicate
that operating personnel must know and obey the employer’s work rules, know the hazards
involved, and use proper protective equipment and tools to work on this equipment. Each
unit of switchgear shall be provided with a “Danger--Keep Away--Hazardous Voltage--Will
Shock, Burn, or Cause Death” sign.
B. Nameplates, Ratings Labels, and Connection Diagrams
Each unit of switchgear shall be provided with a nameplate indicating the manufacturer’s
name, catalog number, model number, date of manufacture, and serial number. Each unit
of switchgear shall be provided with a ratings label indicating the following: voltage rating;
main bus continuous rating; short-circuit rating; fault interrupter ratings including
interrupting and duty-cycle fault-closing; and load break switch ratings including duty-cycle
fault-closing and short-time.
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