|
The switch shall consist of manually operated
load interrupting, SF6 insulated, 600A rotary puffer three
position switches and manually operated vacuum interrupter
fault interrupting tap switches, electronically controlled.
The switches shall be designated G&W Triad Series 1 (TVI
style) (TFI style) incorporating internal ground switches
for the load break switch ways. The switch manufacturer shall
be ISO 9001:2000 and 14001 certified.
A. SWITCH CONFIGURATION
Each switch shall have:
_____ (Qty.) 3-phase load switch ways with
integral ground position.
_____ (Qty.) 3-phase vacuum interrupter
tapped way(s) with gang linked operating handles (TVI
style).
_____ (Qty.) Single phase vacuum interrupter
tapped way(s) with individual operating handles (TVI
style).
_____ (Qty.) 3-phase vacuum interrupter
tapped way(s) with internal three phase mechanism and one
operating handle (TFI style).
Switches shall be designed for: (check)
____ Front access to cables and operators.
____ Front/back access to cables and operators
(four ways max.).
B. SWITCH CONSTRUCTION
Switch contacts and cable entrance terminations shall be contained
in a single welded mild steel tank with entrances internally
connected by copper conductors. Construction shall be a deadfront
design. Switches shall be shipped factory filled with SF6
gas conforming to ASTM D-2472. Switch tanks shall be painted
ASA70 light gray using a corrosion-resistant epoxy paint.
Load break Puffer
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 60 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.
Vacuum Interrupters - The vacuum
interrupter shall consist of vacuum bottles and a spring-assisted
operating mechanism.
For TVI style switches:
The mechanism used shall be designated "Model VI"
for single phase or three phase operation. The mechanism shall
consist of a single vacuum bottle mechanically linked to single
spring-assisted operating mechanism. For three phase operation,
the single phase mechanisms are mechanically linked externally
with an operating handle assembly.
For TFI style switches:
The mechanism used shall be designated "Model FI" for three phase operation. The mechanism shall consist of
three vacuum bottles mechanically linked to a single spring-assisted
operating mechanism.
For all styles:
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.
Reset or closing 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 handle.
C. DESIGN RATINGS
AND STANDARDS
Load break Puffer Switches:
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)
| Voltage class,
kV |
15 |
25 |
35 |
| Impulse level
(BIL), kV |
110 |
125 |
150 |
| Continuous
& load break current, A |
630 |
630 |
630 |
| One minute
withstand (dry), AC kV |
35 |
60 |
70 |
| One minute
withstand (dry), AC kV Production test rating |
34 |
40 |
50 |
| 15 minute
withstand, DC kV |
53 |
78 |
103 |
| Momentary
current, kA, ASYM |
25 |
25 |
25 |
Fault-close
current, kA, ASYM
(3 times) |
25 |
25 |
25 |
| One second
current, kA, SYM |
16 |
16 |
16 |
| Mechanical
endurance, operations |
2000 |
2000 |
2000 |
Vacuum Interrupters:
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 and model)
For TVI style switches:
| Voltage class,
kV |
15 |
25 |
35 |
| Impulse level
(BIL), kV |
95 |
125 |
150 |
| Continuous
& load break current, A |
630 |
630 |
630 |
| 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 optional.
For TFI style switches:
| Voltage class,
kV |
15 |
25 |
| Impulse level
(BIL), kV |
95 |
125 |
| Continuous
& load break current, A |
630 |
630 |
| One minute
withstand (dry), AC kV |
35 |
60 |
One minute
withstand (dry), AC kV
Production test rating |
34 |
40 |
| Symmetrical
interrupting rating, kA |
12* |
12 |
| Asym. interrupting
rating, kA |
19.2 |
19.2 |
*16kA available at 15kV.
D. ANSI C37.60 FAULT INTERRUPTING DUTY
Percent
of Maximum
Interrupting Rating |
No.
of
Fault Interruptions |
| 15-20% |
44 |
| 45-55% |
56 |
| 90-100% |
16 |
Total Number of Fault Interruptions: 116
E. CABLE ENTRANCES
Load break Puffer Switches:
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
Vacuum Interrupters:
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
____ 200 amp Deepwell bushing
F. VACUUM INTERRUPTER
TRIP MODULE
Trip modules shall be provided to sense load and fault current
on each phase of the load tap circuits. The trip modules 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 trip modules 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 -40 degrees C to +65 degrees C.
Trip characteristics (TCC curves) shall
be user selectable. 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. Trip modules shall
not require a computer or other external device for programming
trip settings or other operational parameters.
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.
- Switch operating handle(s) with padlock
provision.
- 12 gauge mild steel padmount enclosure
painted Munsell green with stainless steel hinges and pentahead
locking mechanisms.
- Type 1 vacuum interrupter trip module.
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).
___ Parking stands.
___ Keylock provisions.
___ Current transformers (600:5) (500:1)
(1000:1) on load break ways for current monitoring on automation
schemes.
___ Automatic transfer control package for
a maximum 5 seconds per mechanical switching operation.
___ 24VDC motor actuators.
___ Switch controllers.
___ Remote Terminal Units.
___ Auxiliary switches.
___ Analog voltage sensors.
___ Digital voltage sensors.
___ Type 2 trip modules including ground
fault trip and time delay selector switches (three phase only).
___ Type 3 vacuum interrupter trip modules
including programmable vacuum fluorescent display (VFD) and
RS232/485 port.
|