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This specification covers the requirements
for manual load break SF6 linear puffer (LP) style switches
for overhead applications.
A. SWITCH CONSTRUCTION
All switch components and entrances shall be assembled in
a single welded, mild steel tank. Entrances shall be internally
connected by copper wire ropes and copper bus capable of handling
momentary and continuous current duty. The protection degree
of the switch tank shall be IPX7 rated. Switches shall be
shipped filled with SF6 gas at approx. 9 psig (60kPa).
B. DESIGN RATINGS
AND STANDARDS
Switches are to be designed, tested, and built per applicable sections of ANSI and IEC standards. Certified test reports shall be provided. The manufacturer shall be ISO 9001:2000 and 14001 certified. The switch assembly shall be rated:
| Maximum design voltage,
kV |
15.5
|
27.0
|
38.0 |
| Impulse level kV |
110 |
125 |
150 |
| Continuous and load break
current, Amps |
630 |
630 |
630 |
| One minute withstand 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 (3 times) |
40 |
40 |
40 |
| One second current, kA,
SYM |
25 |
25 |
25 |
| Open gap withstand kV |
200 |
200 |
200 |
| Ten operating overload interrupting
capability Amps |
3000 |
3000 |
3000 |
| Operations Load interrupting
endurance at 600A |
1200 |
1200 |
1200 |
| Mechanical endurance, operations
|
2000 |
2000 |
2000 |
| Maximum gas leakage test cc/second |
10-7 |
10-7 |
10-7 |
C. SWITCH OPERATION
Each switch shall be equipped with an internally mounted rotary
type operating mechanism capable of providing quick-make,
quick-break operation. The mechanism must be capable of delivering
sufficient torque and shall be provided with latches for each
position. The mechanism shall use compression type springs
to assure long life and reliability. All switch positions
are to be clearly identified and padlockable. The operating
mechanism shall be actuated from outside the switch tank by
an external 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. Ambient temperature
range shall be -30°C to +40°C (-22° F to +104°F).
D. SWITCH CONTACTS
Switch contacts shall be linear puffer style tulip-bayonet
design and made of plated, high-conductivity copper alloy
with arcing tips of copper/tungsten alloy. The contacts shall
be designed such that arcing does not occur in the area of
main current interchange and contact pressure will increase
with increasing current flow. The contact nozzle shall have
a converging/diverging geometry which improves the flow of
SF6 into the arc zone. Contact travel shall be three inches
and have sufficient open contact separation to assure efficient
arc extinction and to withstand field DC testing levels and
maintain BIL levels. The stationary contacts shall be supported
independent of the cable entrance bushings. Temperature rise
shall not exceed ANSI C37.71 and IEC 265-1 standards for this
type of device.
E. STANDARD COMPONENTS
For a manual switch the following shall be included:
- Eleven gauge mild steel tank painted light
gray with stainless steel and brass fasteners
- Two lifting eyes
- Crossarm bracket and mounting hardware
- Grounding provisions
- Gas pressure gauge and fill valve
- Three line diagram and corrosion-resistant
nameplate
- Spring operator
- Manual operating handle
- Position indicator
- Padlock provisions for open and close
positions
- Porcelain bushings with copper conductor
and hoodnut
- Lightning arrester provisions
F. MOUNTING
Switches shall be equipped with:
- Crossarm mounting kit
- Polemount bracket (horizontal)
- Polemount bracket (vertical)
G. OPTIONAL COMPONENTS
(check)
The following options shall be supplied:
___ Stainless steel tank
___ Low pressure warning device
___ SF6 density switch
___ 4/0 brass ground lug
___ NEMA 2-hole aerial lugs
___ NEMA 4-hole aerial lugs
___ Clamp style aerial lugs
___ Overpressure relief device
___ Wild life protectors
___ Surge arresters
___ Potential transformers
___ Current transformer (600:5) (500:1)
(1000:1)
___ Automatic transfer control for 6-8 second
transfer
___ Down rod operator kit that does not
include rods
___ Motor actuator
___ Analog voltage sensors
___ 600A porcelain bushings with copper
rod
___ 600A apparatus bushing with elastomeric
insulator and (AL) (CU) rod
___ 600A apparatus bushing with (AL) (CU)
rod
___ Automation accessories
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