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Installation checks and
functional tests
Introduction
This section provides a description of the
inspections, checks and tests to be performed
on the circuit breaker prior to operation in the
metal-clad switchgear.
Inspections, checks and tests without
control power
Vacuum circuit breakers are normally shipped
with their primary contacts open and their
springs discharged. However, it is critical to
first verify the discharged condition of the
spring-loaded mechanisms after de-
energizing control power.
De-energizing control power
in switchgear
When the circuit breaker is mounted in
switchgear, open the control-power
disconnect device in the metal-clad
switchgear cubicle.
The control-power disconnect device is
normally located on the secondary-device
panel in the middle cell of the vertical
section. The normal control-power disconnect
device is a pullout-type fuse holder. Removal
of the fuse holder de-energizes control power
to the circuit breaker in the associated
switchgear cell. In some switchgear
assemblies, a molded-case circuit breaker or
knife switch is used in lieu of the pullout-type
fuse holder.
Hazardous voltage and high-speed moving parts.
Will cause death, serious injury and property damage.
Read instruction manuals, observe safety instructions and use
qualified personnel.
Opening this circuit breaker or switch
accomplishes the same result: control power
is disconnected.
Spring-discharge check
Refer to Figure 1: Type GMSG vacuum circuit
breaker front panel controls on page 8.
Perform the spring-discharge check before
removing the circuit breaker from the pallet
or removing it from the switchgear.
The spring-discharge check should be
performed after de-energizing control power.
This check assures both the tripping and
closing springs are fully discharged.
Note: Do not perform the spring-discharge
check if the circuit breaker is in the CONNECT
position. Open the circuit breaker and rack to
the DISCONNECT position, and then perform
the spring-discharge check.
1. Press red trip pushbutton.
2. Press black close pushbutton.
3. Press red trip pushbutton again.
4. Verify spring-condition indicator shows
DISCHARGED.
5. Verify main contact status indicator shows
OPEN.
9
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