Common Troubleshooting Methods of DC Circuit Breakers

July 29,2022

We all know that circuits can be divided into two types: DC circuits and AC circuits, and according to different circuit classifications, the materials and tool accessories used are completely different. A circuit protection tool was used.

Common faults and solutions of DC circuit breakers:

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The "rejection to close" condition occurs, basically during the closing operation and the reclosing process. This kind of fault is more harmful. For example, when the standby power supply is required to be put into emergency in an accident situation if the standby power supply circuit breaker refuses to close, the accident will be expanded. There are generally three steps to determine the reasons for the "rejection" of the circuit breaker and how to deal with it.

Check whether the previous refusal to close was caused by improper operation (such as the control switch letting go too quickly, etc.), and use the control switch to close it again.

If the closing is still unsuccessful, check the conditions of each part of the electrical circuit to determine whether the electrical circuit is faulty. The inspection items are: whether the closing control power supply is normal; whether the closing control circuit fuse and the closing circuit fuse are in good condition; whether the contacts of the closing contactor are normal; pull the control switch to the "closing time" position, and check the closing Whether the core action is normal.

If the electrical circuit is normal and the circuit breaker still cannot be closed, it means that it is a mechanical fault, and the circuit breaker should be disabled and reported to be scheduled for maintenance.

After the above preliminary inspection, it can be determined whether it is an electrical or mechanical fault. Common electrical circuit faults and mechanical faults are described below.

Common electrical faults

If the red and green lights are not on before the closing operation, it means that there is no control power supply or the control circuit is disconnected. It can check whether the control power supply and the components on the entire control loop are normal, such as: whether the operating voltage is normal, whether the fuse is blown, whether the anti-jump relay is normal, whether the auxiliary contact of the circuit breaker is in good contact, etc. When the green light flashes after the operation are closed, but the red light does not light, the instrument has no indication, the horn sounds, the mechanical opening of the circuit breaker and the closing position indicator are still in the opening position, it means that the position of the operating handle does not correspond to the position of the circuit breaker. Circuit breaker is not closed. The common reasons are: the fuse of the closing circuit is blown or the contact is poor; the closing contactor does not act; the closing coil is faulty.

When the operation circuit breaker is closed, the green light goes out, the red light turns on instantly and then goes out, the green light flashes again and a horn sounds, indicating that the circuit breaker automatically trips after it is closed. The reason may be that the circuit breaker is closed on the faulty line, causing the protection action to trip or the circuit breaker failure cannot keep the circuit breaker in the closed state. If the green light flashes or goes out after the closing operation, the red light does not light up, but the meter has an indication, and the mechanical opening and closing position indicators are in the closing position, indicating that the circuit breaker has been closed. The possible reason is that the auxiliary contacts of the circuit breaker are in poor contact. For example, the normally closed contact is not disconnected and the normally open contact is not closed, causing the green light to flash and the red light to not light; it may also be that the closing circuit is disconnected or the closing red light is burnt out. Operator handle returned prematurely. The operating voltage is too low, and the voltage is below 80% of the rated voltage.