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PART 1- GENERAL
1.1 DESCRIPTION
A. The switch shall consist of manually operated load interrupting, SF6 insulated, 600A
rotary puffer switches and manually operated vacuum interrupter fault interrupting tap
switches, electronically controlled.
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 C37.72, 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. Each switch shall be equipped with 3-phase load switch ways and 3-phase vacuum
interrupter tapped way(s), as indicated on the one-line diagram.
B. Switches shall be designed for front access to cables and operators.
2.2 SWITCH CONSTRUCTION
A. General
All switch components and entrances shall be assembled in a totally welded mild steel
tank. Entrances shall be internally connected by copper conductors capable of handling
momentary and continuous current duty. The switch shall contain no electrically floating
metallic parts or components. Construction shall be a deadfront design. Switch tanks
shall be painted ASA70 light gray using a corrosion-resistant epoxy paint.
B. Load Break Switch
Each switching way is to be equipped with an internally mounted operating mechanism
capable of providing quick-make, quick-break operation in either switching direction. The
mechanism must be capable of delivering sufficient torque and shall be provided with
latches for each position to assure load interrupting, fault closing and momentary ratings.
All switch positions are to be clearly identified, padlockable and adaptable to keylock
schemes. The operating mechanism shall be actuated from outside the switch tank with
an operating handle. The operating shaft shall be made of stainless steel providing
maximum corrosion resistance. A double "O" ring type operating shaft seal shall be used
for a leak resistant, long life seal. Switch contacts shall be of a rotary puffer design made
with copper alloy contacts with silver plating to assure permanent, low contact resistance.
Each rotating contact simultaneously disengages from two fixed contacts, thus providing
two break points per phase giving improved interrupting capability compared to single
break contact systems. Contact travel shall be 90 degrees to assure efficient arc
extinction and a wide open contact gap. Arcing is confined away from the main contact
surfaces. The stationary contacts shall be supported independent of the cable entrance
bushings, eliminating possible misalignment. Auxiliary blades used for load interruption
are not acceptable.
C. Vacuum Interrupters
The vacuum interrupter shall consist of vacuum bottles and a spring-assisted operating
mechanism. The mechanism used shall be designated "Model FI" for three phase
operation only. The mechanism shall consist of three vacuum bottles mechanically linked
to a single spring-assisted operating mechanism. The vacuum interrupter operating
mechanism shall consist of the support assembly, linkage, spring latch mechanism, and
solenoid utilized for electronic tripping. Maximum interrupting time shall be three cycles
(50 msec). The movable contact shaft shall be flagged to indicate the contact position,
open or closed. This contact position indicator shall be fully visible through viewing
windows supplied in the switch tank. Each tap phase is to be equipped with an individual
600A vacuum interrupter fully enclosed in an SF6 insulated switch tank. Electrical
opening shall be by a solenoid that is activated from sources external to the switch tank.
Closing (reset) of the vacuum interrupter shall be mechanical with the use of an external
operating handle. The mechanical linkage assembly shall provide for a "trip-free" operation
which allows the vacuum interrupter to interrupt independent of the operating lever.
2.3 DESIGN RATINGS
A. Load Break Switches
The switch shall be rated: (choose appropriate column)
SELECTION OF RATINGS |
IEEE/IEC |
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 |
12 |
Mechanical Endurance, Operations |
2000 |
2000 |
Load Break Operations at 600 Amperes |
500 |
500 |
B. Vacuum Interrupters
The vacuum interrupter assembly shall be rated: (choose appropriate column)
SELECTION OF RATINGS |
IEEE/IEC |
Maximum Design Voltage, kV |
15.5 |
27 |
Impulse Level (BIL) Voltage, kV |
95 |
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 |
12 |
Asymmetrical Interrupting Rating, kA |
19.2 |
19.2 |
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 CABLE ENTRANCES
A. Load Break Puffer Switches
Cable entrances shall be tested to IEEE 386 and be, as indicated on the switch drawing:
- ____ 600 amp G&W Quik-Change disconnectable apparatus bushing,
- ____ 600 amp Apparatus bushing,
- ____ 600 amp Universal bushing, or
- ____ 200 amp Deepwell bushing.
B. Vacuum Interrupters
Cable entrances shall be tested to IEEE 386 and be, as indicated on the switch drawing:
- ____ 600 amp G&W Quik-Change disconnectable apparatus bushing,
- ____ 600 amp Apparatus bushing,
- ____ 600 amp Universal bushing, or
- ____ 200 amp Deepwell bushing.
2.5 VACUUM INTERRUPTER CONTROL
An electronic assembly shall be provided to sense load and fault current on each phase of the
load tap circuits. The electronic control shall be powered from the current transformers mounted
inside the SF6 insulated switch tank. No external power source shall be required for overcurrent
protection. The electronic control shall monitor the current on the individual phases of the load
tap circuits using input from the internal current transformers. Electronic trip capability shall be
selectable for each phase. Temperature range shall be -30C to +50C. Minimum trip selection
shall be accomplished with selector knobs inside the electronic enclosure. Trip time current
characteristics (TCC) shall be field selectable using a dip switch. Maximum time for power up
and ready-to-trip when closing on a circuit shall be ten percent of the trip time or 1/2 cycle,
whichever is greater. Trip selection may be made with the load taps energized. The electronic
controller is preset for three phase trip. Single phase trip is not available.
2.6 ENCLOSURE
Enclosures shall be made of 12 gauge galvanized steel and manufactured to ANSI C37.72 and
C57.12.28 standards. The enclosure shall be mounted independent of the switch allowing
removal for ease of cable installation or future replacement if required. Enclosures shall be
tamper-resistant incorporating hinged access doors with pentahead locking bolts 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
The bulk SF6 gas supply and each individual switch shall be tested for moisture content. Each
individual switch shall undergo a mechanical operation check and a leak test. The switch shall
be factory filled with SF6 and AC hi-pot tested one minute phase-to-phase, phase-to-ground and
across the open contacts. Circuit resistance shall be checked on all ways. Switches will be
shipped factory filled with SF6 gas. Tank shall be designed to withstand 15 psig internal
pressure and an external pressure of 14 psig without affecting the performance of the switch.
2.8 STANDARD COMPONENTS
The following shall be included as standard:
- Welded steel tank painted light gray with stainless steel and brass fasteners.
- Lifting provisions.
- Gas pressure gauge and fill valve.
- Stainless steel three line diagram and corrosion-resistant nameplates.
- Parking stands.
- Switch operating handle(s) with padlock provision and end stops.
- Type 2 electronics package including ground fault trip and time delay selector switches (three phase only).
- 12 gauge galvanized steel padmount enclosure painted Munsell green with stainless steel hinges and pentahead locking mechanisms.
2.9 OPTIONS
The following options shall be supplied: (check as appropriate)
- ____ 304 stainless steel tank.
- ____ 304 stainless steel enclosure.
- ____ Front/back access to cables and operators.
- ____ Temperature compensated gas density gauge.
- ____ Low pressure warning device.
- ____ SF6 density switch for SCADA or remote indication of SF6.
- ____ 4/0 brass ground lug(s).
- ____ Keylock provisions.
- ____ Keylocks to lock in open position.
- ____ 600 amp Apparatus Bushings.
- ____ 600 amp Universal Bushings.
- ____ Current transformers for load break ways.
- ____ Potential transformers for voltage monitoring and/or control power.
- ____ Automatic transfer control type ATC451-4.
- ____ Automatic transfer control type ATC101.
- ____ Motor actuators for remote switch operation.
- ____ Stationary switch control(s) for remote switch operation and SCADA integration.
- ____ DC portable switch controls for remote switch operation and SCADA integration.
- ____ Remote terminal units and communication packages for SCADA integration.
- ____ Operations counters.
- ____ Auxiliary switches for remote switch position indication.
- ____ Analog voltage sensors.
- ____ Digital voltage sensors.
- ____ Voltage indication panel(s).
- ____ Type 2 vacuum interrupter control including ground fault trip and time delay selector switches (three phase only).
- ____ Type 3 vacuum interrupter control including ground fault trip, inrush restraint, programmable vacuum fluorescent display (VFD) and RS232/485 port.
- ____ Type 4 vacuum interrupter control (same as Type 3 with laptop programming only).
- ____ External power / trip for vacuum interrupter control.
- ____ Refill kit consisting of regulator, hose and SF6 bottle.
2.10 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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