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The switch shall consist of manually operated
fault interrupting, SF6 insulated, vacuum interrupters, electronically
controlled. The switch manufacturer shall be ISO
9001:2000 and 14001 certified.
A. SWITCH CONFIGURATION
Each switch shall have:
_____ (Qty.) 3-phase vacuum interrupter
tapped way(s) with gang linked operating handles (model VI).
_____ (Qty.) 3-phase vacuum interrupter
tapped way(s) with single operating handles (model FI, 15.5-27kV).
_____ (Qty.) single phase vacuum interrupter
tapped way(s) with individual operating handles (model VI).
Switches shall be designed for: (check)
_____ Front access to cables and operators.
_____ Front/back access to cables and operators.
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.
Vacuum Interrupters
- The vacuum interrupter shall consist of vacuum bottles and
a spring-assisted operating mechanism. The mechanism used
shall be designated: (check)
____ Model VI for single or three phase
operation. 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.
____ Model FI for three phase operation
only. 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 extaernal 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.
C. DESIGN RATINGS
AND STANDARDS
The vacuum interrupter shall be a non-reclosing, manual reset
device incorporating vacuum bottles. It shall be designed,
tested and built per application sections of ANSI C37.60-1981
and C37.72-1987. The vacuum interrupter assembly shall be
rated: (select column)
Model VI Vacuum Interrupter
| Maximum design
voltage, kV |
15.5 |
27.0 |
38.0 |
| Impulse level
(BIL), kV |
95 |
125 |
150 |
| Continuous
& load break current, A |
600 |
600 |
600 |
| One minute
withstand (dry), AC kV |
35 |
60 |
70 |
| One minute
withstand (dry), AC kV Production test rating |
34 |
40 |
50 |
| Symmetrical
interrupting rating, kA* |
12 |
12 |
12 |
| Asym. interrupting
rating, kA |
19.2 |
19.2
|
19.2 |
* 18kA sym. available.
FI Ratings
| Max. Voltage, kV |
15.5 |
27 |
38 |
| BIL Impulse, kV |
95 |
125 |
150 |
| One Minute Withstand, AC
kV |
50 |
60 |
70 |
| 15 Minute Withstand, DC
kV |
53 |
78 |
103 |
| Continuous, A |
630 |
630 |
630 |
| Interrupting, kA sym* |
12 |
12 |
12 |
*16kA available at 15kV
D. ANSI C37.60 FAULT INTERRUPTING DUTY
| Percent of
Maximum Interrupting Rating |
Approx. Interrupting
Current, Amps |
No. of Fault
Interruptions |
| 15-20% |
2,000 |
44 |
| 45-55% |
6,000 |
56 |
| 90-100% |
12,000 |
16 |
Total Number of Fault Interruptions: 116
E. 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
____ 200 amp Deepwell bushing
____ 200 amp Deepwell bushing with deadbreak
insert
F. VACUUM INTERRUPTER
ELECTRONIC 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.
G. 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.
H. 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.
I. 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.
- For Model VI mechanism: Type 1 vacuum
interrupter electronics package including a selector switch
for single or 3-phase operation and individual phase trip
levels. For Model FI mechanism: Type 2 electronics package
Including ground fault trip and time delay selector switches
(three phase only).
J. 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).
___ Current transformers (500:1) (1000:1)
___ 24VDC motor actuators.
___ Switch controllers.
___ Remote Terminal Units.
___ Digital voltage sensors.
___ Type 3 vacuum interrupter electronics
package including programmable vacuum fluorescent display
(VFD) and RS232/485 port.
___ 18kA symmetrical interrupting rating
(model VI only).
___ Refill kit consisting of regulator,
hose and 10 or 20 lb SF6 bottle.
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