GE Industrial Solutions PowerVac PV-VL 13.8-1000-0 and -1 - Manual (Page 62)

Page 62 GEH 6468A - Power/Vac VL Breaker
20. STATIONARY CUBICLE SUB-
ASSEMBLY
20.1 INTRODUCTION
The breaker cubicle sub-assembly is the stationary
housing for the removable breaker unit. It contains
the primary disconnects, elevating mechanism,
buses, current transformers, and secondary control
wiring.
20.2. DESCRIPTION OF MAJOR
COMPONENTS
SECONDARY ENCLOSURE The secondary en-
closure consists of a compartment with a hinged
door or panel. Terminal blocks, fuse blocks, and
some control devices are mounted inside the
enclosure on the side sheets.
BREAKER ELEVATING MECHANISM The ele-
vating mechanism is designed to raise the breaker
unit into the operating position and to lower the
breaker to the disconnected position. It consists of a
motor, heavy duty jack screws, jack nuts, and a
carriage frame. Rails are built into the breaker
frame to guide it into position. By means of
interlocks, the breaker cannot be lowered or raised
until it has been tripped. The breaker contacts can
only be closed when the breaker is in the connected
position. For more detail, refer to GEH-1802.
ELEVATING MOTOR An optional elevating motor
may have been furnished for each breaker cubicle
sub-assembly. A short cable with a plug is provided
and must be connected into the receptacle below
the motor mounting. A selector switch is mounted
on the motor for reversing the motor direction. This
selector switch should not be used to start and stop
the elevating gear motor.
PRIMARY DISCONNECTS The primary dis-
connect devices utilize silver to silver contacts to
insure against reduction of current carrying capacity
due to oxidation of the contact surfaces. These
contacts are of the high pressure line contact tube
and socket design, the tube being backed up by
heavy garter springs to insure contact pressure.
BUSES The main buses are enclosed in a metal
compartment with removable covers to provide
accessibility. The buses are supported by flame
retardant, track resistant,
glass laminate
insulating material and porcelain, which is
practically impervious to moisture, and an
excellent dielectric. No additional coating is
necessary.
The bus insulation is an extruded thermoplastic
insulation sleeve, suitable for 105 degree C
operating temperatures. The bus bars are inserted
into the sleeves leaving only the bolted joints
exposed. The bus terminates before and after the
breaker unit. Current transformers may be located
along the bus, on either side of the breaker, for
control applications.
BREAKER TESTING PROVISIONS Optional
pro- visions for testing the breaker unit after
removing it from the cubicle sub-assembly can be
furnished. The test equipment is located on a
panel adjacent to the breaker compartment. It
consists of a test coupler to provide control power
to operate the breaker, and push buttons to trip
and close the breaker electrically.
CONNECTIONS The main bus bars and other
connection bars are made of copper, and the
contact surfaces are silver plated. All field
assembled joints in the primary conductors should
be made as follows:
1. Wipe silver clean with a clean cloth and de-
natured alcohol. If badly tarnished, use a non-
abrasive silver polish. Do not use steel wool,
sandpaper, or any abrasive on the silvered
surface. Avoid handling of cleaned surfaces as
much as possible.
2. After cleaning, apply grease 0282A2048P009
to the silvered surfaces so that the contact area
will be thoroughly sealed. Using standard washer,
lock washer, and nut, together, tighten joints to
the torque values shown below.
BOLT CONNECTION TIGHTENING
Bolt Size Torque
1/2 x 13 50 - 60 foot pounds
5/8 x 11 60 - 70 foot pounds