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Removal from switchgear
Prior to performing any inspection or
maintenance checks or tests, the circuit
breaker must be removed from the
switchgear. The "Installation checks and initial
functional tests" section (refer to page 8)
describes the removal procedure in detail.
The principal steps are repeated here for
information and guidance, but without the
details of the preceding section.
1. The first step is to de-energize the circuit
breaker. Figure 32: Trip-control
pushbutton (lower button) illustrates the
location of the trip control on the circuit
breaker operator panel. Depressing the
trip pushbutton opens the circuit breaker
prior to removal from the switchgear.
2. The second step in the removal procedure
is to de-energize control power to the
circuit breaker. Open the control-power
disconnect device.
3. Rack the circuit breaker to the
DISCONNECT position.
4. Perform the spring discharge check. This
is done by first depressing the red trip
pushbutton. Second, depress the black
close pushbutton. Third, depress the red
trip pushbutton again, and observe the
spring condition indicator. It should read
DISCHARGED.
5. Remove the circuit breaker from the
switchgear. Refer to page 10 of
"Installation checks and initial functional
tests" section of this instruction manual
for special instructions and precautions
regarding removal of a circuit breaker not
at floor level.
6. The circuit breaker can be located either
on the floor or on a pallet. Each circuit
breaker has four wheels and handles to
allow one person to maneuver the unit on
a level surface without assistance.
Checks of the primary power path
The primary power path consists of three
vacuum interrupters and three upper-primary
and three lower-primary disconnects. These
components are checked for cleanliness and
condition. The vacuum interrupters are also
checked for vacuum integrity.
Some test engineers prefer to perform the
contact-erosion check during the manual-
spring charging check of the operator, since
charging of the springs is necessary to place
the contacts in the CLOSED position. Also, the
vacuum-integrity check is usually performed
in conjunction with the high-potential test.
These instructions follow the
recommendation these tests (contact-erosion/
manual-spring charging check and vacuum
integrity/high-potential tests) should be
combined as described.
Cleanliness check
Figure 33: Type GMSG vacuum circuit breaker
showing vacuum interrupters and primary
disconnects (barriers removed) is a side view
of the type GMSG vacuum circuit breaker with
the outer-insulating barriers removed to show
the vacuum interrupter and the upper- and
lower-primary disconnects.
All of these components must be cleaned and
free of dirt or any foreign objects. Use a dry
lint-free cloth. For stubborn dirt, use a clean
cloth saturated with isopropyl alcohol (except
on a vacuum interrupter).
For stubborn dirt on a vacuum interrupter,
use a cloth and warm water and a small
amount of mild liquid-household detergent as
a cleaning agent. Dry thoroughly using a dry
lint-free cloth.
Figure 32: Trip-control pushbutton
(lower button)
Figure 33: Type GMSG vacuum
circuit breaker showing vacuum
interrupters and primary disconnects
(barriers removed)
39
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