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
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
De-energizing control power in
When the circuit breaker is mounted in
switchgear, open the control-power
disconnect device in the metal-clad
The control-power disconnect device is
normally located on the secondary-device
panel in the upper 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.
Opening this circuit breaker or switch
accomplishes the same result: control
power is disconnected.
Installation checks and
Hazardous voltage and high-speed moving parts.
Will cause death, serious injury and property damage.
Read instruction manuals, observe safety instructions and use
Spring-discharge check (refer to
Figure 1: Type 38-3AH3 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-
1. Press red trip pushbutton.
2. Press black close pushbutton.
3. Press red trip pushbutton again.
4. Verify spring-condition indicator shows
5. Verify main contact status indicator