Typical Specifications
Padmount Linear Puffer SPRAM/PRAM Switchgear
Two Position

The switch shall consist of manually operated load interrupting, SF6 insulated, 600A linear puffer switches. The switch manufacturer shall be ISO 9001:2000 and 14001 certified.

A. SWITCH CONFIGURATION
Switches shall be configured:

_____ Front access with diagonal bushings (SPRAM-F style). 

_____ Front access with in-line bushings (PRAM-F style). 

_____ Front/back access with in-line bushings (PRAM-L style).

Each switch shall have:

_____ (Qty.) Load break switched ways

_____ (Qty.) 3-phase unswitched solid bus tap ways

B. SWITCH CONSTRUCTION
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.

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 for 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 a tulip-bayonet design and made of plated, high-conductivity copper alloy with arcing tips of copper/tungsten alloy to assure permanent low resistance and to avoid sticking during operation. The contacts shall be designed such that arcing does not occur in the area of main current interchange and contact pressure will increase with increased current flow. The stationary contacts shall be supported independent of the cable entrance bushings, eliminating possible misalignment. The contact nozzle shall have a converging/diverging geometry which improves the flow of SF6 into the arc zone. Contact travel shall be a minimum of 3 inches and have sufficient open contact separation to assure efficient arc extinction and to withstand field DC testing levels and maintain BIL levels. Switch contacts shall be clearly visible in the open position through viewing windows. Auxiliary blades used for load interruption are not acceptable.

C. DESIGN RATINGS AND STANDARDS
Switches shall be designed, tested and built per ANSI C37.72-1987 and IEC 265 standards. Certified test reports shall be provided. The switch shall be rated: (select column)

D. CABLE ENTRANCES
Cable entrances shall be tested to ANSI/IEEE 386 and be one or more of the following: (check)

____ 600 amp Quik-Change disconnectable apparatus bushing

____ 600 amp Apparatus bushing

____ 600 amp Universal bushing

E. ENCLOSURE
Enclosures shall be made of 12 gauge mild 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.

F. 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 effecting the performance of the switch.

G. 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 mild steel padmount enclosure painted Munsell green with stainless steel hinges and pentahead locking mechanisms.

H. OPTIONAL COMPONENTS (check)
The following options shall be supplied:

___ Stainless steel tank.

___ Stainless steel enclosure.

___ Low pressure warning device.

___ SF6 density switch for SCADA or remote indication of dielectric.

___ 4/0 brass ground lug(s).

___ Keylock provisions.

___ Current transformer for current monitoring for automation schemes (500:1) (1000:1).

___ Automatic transfer control package with a total transfer time of 8 seconds.

___ Automatic transfer control package with digital voltage sensors for a maximum of 5 cycles per mechanical switching operation. Overall transfer time including required sensor and control response delays is 20-30 cycles.

___ Motor actuators.

___ Switch controls.

___ Integral distribution automation package.

___ Auxiliary contacts.

___ Analog voltage sensors.

___ Digital voltage sensors.

___ SF6 refill kit consisting of regulator, hose and 10 or 20 lb SF6 bottle.