Installation checks and functional tests
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.
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 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.
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- 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.
