Westinghouse PS-1002, Инструкция, Страница: 20 / 36

1 8
completion, pressure test the transformer as described in
Section
2.3
of this booklet.
Cast Resin Welded Bush ings ( Type CR W) (See Fig. 15)
Type CRW bushings can be used for wall mounted
1 .2
kv
class applications for use indoors or within an enclosure.
This is a cast resin, hermetically-sealed bushing with a
metal flange for welding to a non-magnetic steel plate on
the transformer tank. Both the conductor and flange are
permanently attached and sealed to the cast epoxy body.
Fig.
15 Type CR W Bushing
Only flexible connections should be made to the air
or liquid ends of the bushing conductor in order not to
apply thermal expansion forces to the bushing. As a gen­
eral rule, a maximum cantilever load of 100 pounds act­
ing at the end of the bushing conductor should not be
exceeded.
For axial loads applied to the bushing connector, a
maximum loading of
1 00
pounds is permissible. Should
maintenance be required due to damage, refer to Instruc­
tion Leaflet
47-06 1 -8 ,
"Instruction for Weld-On, Cast
Resin Bushing, Type CRW".
Cast Rolled Flange Bushing (Type CRFW) (See Fig. 16)
Type CRFW bushings can be used for wall mounted
1 .2
kv class applications for use indoors or within an en­
closure.
An
insulating epoxy resin is cast around a solid
copper or aluminum conductor to provide an oil tight
seal. A stainless steel flange is swaged over silicone rubber
o-rings, forming a sealed, weldable assembly. The b ushing
can be welded to the bushing plate by TIG welding tech­
niques without heat sinks. In the bolted version the stain·
less steel flange incorporates a gasket retaining groove.
The assembly can then be bolted to the transformer with
an aluminum clamping plate, using either a cork-Buna
"N" or nitrile ring gasket to seal the bushing to the wall.
Make only flexible connections to the air or liquid ends
of the bushing conductor in order to limit the thermal ex­
pansion forces on the bushing. As a general rule, a maxi­
mum cantilever or axial load of
1 00
pounds acting at the
end of the bushing conductor should not be exceeded.
For detailed instructions on application, installation,
or replacement, request Instruction Leaflet
4 7-OS 1 - 1
for
the weld-on version, or
47-05 1 -2
for the bolted version.
5 . 1 4
Lightning Arresters
Transformers may be furnished with Type
IV L
Intermedi­
ate Class or Type CPL Station Class Lightning Arresters
as optional items. These arresters are shipped separately
in a protective carton or crate. On receipt, unpack the
units and examine for breakage or other damage , espe­
cially to the porcelains. Check the parts with the packing
list. Each arrester pole should include: one or more ar­
rester units which add up to the pole voltage rating; one
ground terminal bracket ; one line terminal ; and hardware
to connect units together. In order to prevent arrester
damage that can result in violent arrester failure take the
following precautions.
CAUTION
1 .
When installing the arrester, all mounting feet must be
flush before tigh
t
enin g bolts. Shim if necessary.
2 . The arrester should not be climbed for any reason.
3. The line terminal must not be used to lift the arrester.
4.
Arrester exhaust port should be directed away from
protected equipment and other arrester poles.
5.
Poles must be made of the serial numbered units iden­
tified on the master nameplate (the master nameplate is
located on the bottom arrester unit).
Arrester mounting brackets are supplied welded or
bolted to the transformer tank. Each arrester pole should
be connected to the same ground as the transformer. Line
connections should be made in such a way that no exces­
sive mechanical strain is placed on the arrester. The canti­
lever strength of the Type IVL Arrester is
5000
foot
pounds and of the Type CPL Arrester
5800
foot pounds.