|
PART 1- GENERAL
1.1 DESCRIPTION
A. The switch shall consist of manually operated load interrupting, SF6 insulated, 600A linear puffer switches.
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 as rated.
B. The manufacturer shall furnish certification of ratings of the load break switch upon request.
C. The switch shall comply with requirements of the latest revisions of applicable industry
standards, including:
(a) IEEE C37.71, 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 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 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 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.
2.2 DESIGN RATINGS
A. Load Break Switches
The switch shall be rated: (choose appropriate column)
SELECTION OF RATINGS |
IEEE/IEC |
Maximum Design Voltage, kV |
15 |
25 |
35 |
Impulse Level (BIL) Voltage, kV |
110 |
125 |
150 |
Continuous Current, Amperes |
630 |
630 |
630 |
Load break Current, Amperes |
630 |
630 |
630 |
One Minute Withstand (dry), AC kV |
50 |
60 |
70 |
Ten Second Withstand (wet), AC kV |
45 |
50 |
60 |
15 Minute Withstand, DC kV |
53 |
78 |
103 |
Momentary Current, kA, ASYM |
40 |
40 |
40 |
Fault-Close Current, kA, ASYM |
40 |
40 |
40 |
One Second Current, kA, SYM |
25 |
25 |
25 |
Mechanical Endurance, Operations |
2000 |
2000 |
2000 |
Load Break Operations at 600 Amperes |
1200 |
1200 |
1200 |
2.3 CABLE ENTRANCES
Cable entrances shall be tested to IEEE 386 and be, as indicated on the switch drawing:
- ____ 600 amp porcelain bushings with copper rod (15.5-27kV only),
- ____ 600 amp apparatus bushings with (AL) (CU) rod, or
- ____ 600 amp apparatus bushings with elastomeric insulator and (AL) (CU) rod.
2.4 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.
2.5 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.
- Switch operating handle(s) with padlock provision and end stops.
2.6 OPTIONS
The following options shall be supplied: (check as appropriate)
- ____ 304 stainless steel tank.
- ____ 304 stainless steel enclosure.
- ____ 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).
- ____ 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).
- ____ Refill kit consisting of regulator, hose and SF6 bottle.
2.7 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.
|
