Why does the circuit breaker experience a skip trip phenomenon? What is the handling method?


Release time:

2023-04-19

The circuit breaker is used to automatically cut off the current after the current exceeds the trip setting and play the role of circuit protection. During the operation of electrical equipment, we often encounter the scene where the circuit breaker trips, resulting in a short circuit fault. The reasons for the problem and how to deal with it are explained in detail below.

The circuit breaker is used to automatically cut off the current after the current exceeds the trip setting and play the role of circuit protection. During the operation of electrical equipment, we often encounter the scene where the circuit breaker trips, resulting in a short circuit fault. The reasons for the problem and how to deal with it are explained in detail below.

Miniature circuit breaker .jpg inside the distribution box

First, the conditions for skipping the trip

1. The fault current reaches or exceeds the set action current value

2. The fault current duration reaches the time of the set action

Second, the reasons for skipping the trip

1. The load capacity of the main switch is less than the capacity of the sum of the sub-switch loads.

2. The main switch has a leakage protection device but the sub-switch does not, and the main switch tripps when the leakage of the electrical appliance is greater than or equal to 30 mA.

3. The protection of the two-stage circuit breaker does not match, try to use the same brand of circuit breaker.

4. Often operate the main switch with load, resulting in electric shock, carbonization, poor contact, increased resistance, current increase, heating trip.

5. The protection of the lower circuit breaker configuration cannot correctly judge the fault (such as single-phase ground fault but zero sequence protection is not configured).

6. The aging of the circuit breaker leads to a longer shunt trip time, and it is necessary to replace a subswitch whose shunt trip time is less than that of the previous switch.

The circuit breaker switch of the high-voltage cabinet .jpg

Third, the solution

When the superior circuit breaker trips, if it is found that there is a shunt protection action, but the shunt circuit breaker is not tripped, the stage circuit breaker is disconnected, and then the superior circuit breaker is restored; If it is found that each shunt protection is not operating, it should be checked whether the equipment within the power outage range is faulty, if there is no fault, the superior circuit breaker can be closed, and each shunt circuit breaker can be sent one by one. When the power circuit breaker tripped, it can be determined that the circuit breaker is a faulty circuit breaker. The line can be isolated for repair and replacement.

In short, line protection, whether it is a short-circuit fault or a ground fault, is the same reason, and it is by judging the magnitude and duration of the current to act. Strictly speaking, the timing is more important, because the fault current is likely to meet the protection rating of the multi-stage circuit breaker at the same time.