Typical Specifications
Padmount Vacuum Interrupters

PART 1- GENERAL

1.1    DESCRIPTION

        A.     The switch shall consist of manually operated fault interrupting, SF6 insulated, vacuum

                interrupters, 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 vacuum interrupter tapped way(s) with gang

                linked operating handles (model VI), 3-phase vacuum interrupter tapped way(s) with single

                operating handles (model FI, 15.5-27kV), and single phase vacuum interrupter tapped

                way(s) with individual operating handles (model VI), 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.     Vacuum Interrupter

                The vacuum interrupter shall consist of vacuum bottles and a spring-assisted operating

                mechanism. The mechanism used shall be designated either Model VI for single or three

                phase operation or Model FI for three phase operation only.  For Model VI the interrupter

                shall consist of a single vacuum bottle mechanically linked to a spring-assisted operation

                mechanism.   For three phase operation, the single phase mechanisms are mechanically

                linked externally with an operating handle assembly.  For Model FI the interrupter shall

                consist of three vacuum bottles mechanically linked to a single spring-assisted

                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

        The vacuum interrupter assembly shall be rated: (choose appropriate column)

* 38 kV available in model VI only.

**Optional 20 kA symmetrical interrupting, 600 amp continuous is available at all voltage classes (model VI only). 

        ANSI C37.60 Fault Interrupting Duty

2.4    CABLE ENTRANCES

        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 CONROL

        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 -30°C to +50°C. 

        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 vacuum interrupter control shall be designated as G&W Type 1.

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.
• Grounding provisions for switch tank and all cable entrances.
• Stainless steel three line diagram and corrosion-resistant nameplates.
• Parking stands.
• Switch operating handle(s) with padlock provision and end stops.
• 12 gauge galvanized steel padmount enclosure painted Munsell green with stainless steel hinges and pentahead locking mechanisms.
• Control:
• For Model VI mechanism: Type 1 vacuum interrupter control including a selector switch for single or 3-phase operation and individual phase trip levels.
• For Model FI mechanism: Type 2 control including ground fault trip and time delay selector switches (three phase only). 

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.
• ____ 20kA symmetrical interrupting rating.
• ____ 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.