Troubleshooting
Introduction
Troubleshooting operations are described in the following tables, with the checks or repairs to be carried out in relation to the probable causes of the malfunction indicated. They are classified into the following events:
-
Repetitive tripping
-
Circuit breaker fails to close (manually operated circuit breaker)
-
Circuit breaker fails to close (motor-operated circuit breaker)
Repetitive Tripping
|
Indication |
Probable cause |
Checks or repairs |
|---|---|---|
|
SD |
Supply voltage to the MN undervoltage trip release is too low or subject to significant variations |
Check the power supply for the release (for example, a supply powering motors with high-power ratings may be unstable). If so, connect the release to a clean or stable supply. |
|
Supply voltage to an MX shunt trip release applied unintentionally |
Check that the release connection is correct compared to the installation diagram. |
|
|
SD and SDE |
Operating temperature too high |
Check the switchboard ventilation and the temperature in the room. |
Circuit Breaker Fails to Close (Manually Operated Circuit Breaker)
The following table shows the checks or repairs to be carried out in relation to the probable causes of the malfunction indicated.
|
Indication |
Probable cause |
Checks or repairs |
|---|---|---|
|
SD |
MX shunt trip release energized MN undervoltage trip release not energized |
Check that the release connection is correct compared to the installation diagram. |
|
OF |
Circuit breaker interlocked |
Check the installation and interlock diagram (mechanical or electrical) for both circuit breakers. |
Circuit Breaker Fails to Close (Motor-Operated Circuit Breaker)
The following table shows the checks or repairs to be carried out in relation to the probable causes of the malfunction indicated.
|
Indication |
Probable cause |
Checks or repairs |
|---|---|---|
|
OF |
Close instruction not operational |
Check the Auto position of the selector on the front of the circuit breaker. Also check:
|