(1) Fault phenomenon: The circuit breaker refuses to close. The possible reasons and solutions are as follows.

There are two main reasons for refusing to close the circuit: electrical faults and mechanical reasons.

Electrical faults mainly include the following situations:

1) If the red and green indicator lights do not light up before the closing operation, it indicates that there is a disconnection or no control power supply in the control circuit. You can check whether the control power supply and the components on the entire control circuit are normal.

2) When the red light does not light up, the green light flashes, and the accident speaker sounds after the closing operation, it indicates that the position of the operating handle does not correspond to the position of the circuit breaker, and the circuit breaker is not closed. The reason is that the fuse of the closing circuit fuse is blown or has poor contact, and the fuse should be replaced; The closing coil has malfunctioned and should be replaced.

3) After the closing operation, the green light goes out and the red light is on, but in an instant, the red light goes out again, the green light flashes, and the accident speaker sounds, indicating that the circuit breaker automatically trips again after being closed. The circuit breaker is closed on the fault line, causing protection action to trip or mechanical failure of the circuit breaker, which cannot keep the circuit breaker in the closed state.

4) If the green light goes out and the red light does not light up after the closing operation, but the ammeter already indicates, it means that the circuit breaker has been closed. Possible reasons may be poor contact between the auxiliary contacts of the circuit breaker or the control switch contacts, or disconnection of the trip coil causing the circuit to be disconnected, or melting of the control circuit fuse, or damage to the indicator light bulb.

Mechanical failures mainly include the following situations:

1) The connecting rod of the transmission mechanism has become loose and detached.

2) The closing iron core is blocked.

3) The mechanism did not reset after the circuit breaker was opened.

4) The tripping mechanism trips.

5) The closing spring of the spring control mechanism has not stored energy.

6) The release link has not returned.

7) The opening lock hook is not hooked or the adjustment of the opening four-bar linkage mechanism does not cross the dead point, because it cannot maintain the closing.

8) Sometimes when the circuit breaker is closed, it repeatedly performs opening and closing actions, and the auxiliary contact of the switch opens too early.

The processing method is as follows:

1) Close the control switch again to check if the previous refusal to close was caused by improper operation (such as releasing the control switch too quickly).

2) Check the condition of each part of the electrical circuit to determine if there is a fault in the electrical circuit. The specific method is to check whether the closing control power supply is normal; Check whether the closing control circuit and closing fuse are in good condition; Check if the contacts of the closing contactor are normal (such as the electromagnetic operating mechanism); Turn the control switch to the "closed" position; Check if the closing iron core is in motion (the inspection of hydraulic mechanism, starting mechanism, and spring mechanism is the same). If the closing iron core operates normally, it indicates that the electrical circuit is functioning properly.

3) If the electrical circuit is normal but the circuit breaker still cannot be closed, it indicates a mechanical fault. The circuit breaker should be stopped and reported to the relevant leaders for maintenance and handling. After the preliminary inspection above, it can be determined whether the fault is electrical or mechanical.

(2) Fault phenomenon: The circuit breaker refuses to trip, and the possible reasons and solutions are as follows.

The "refusal to trip" of circuit breakers poses a great threat to the safe operation of the system. Once a unit fails and the circuit breaker refuses to trip, it will cause the higher-level circuit breaker to trip, known as "leapfrog tripping".

1) Before the fault circuit breaker is identified, if the ammeter reading of the main transformer power supply circuit breaker is full scale and the abnormal sound is strong, the power supply of the circuit breaker should be disconnected to prevent burning out the main transformer.

2) When the higher-level backup protection action causes a power outage, if it is found that there is a branch protection action but the circuit breaker has not tripped, the circuit breaker that refused to trip should be disconnected and the higher-level power circuit breaker should be restored; If it is found that none of the branch protections have been activated (or it may be due to protection rejection), then the equipment within the power outage range should be checked for any faults. If there are no faults, all branch circuit breakers should be disconnected, and after closing the power circuit breakers, each branch circuit breaker should be tested one by one. If the power circuit breaker trips again when it is sent to a certain branch, it can be determined that the circuit breaker is not faulty and "refuses to trip". It should be isolated while restoring power to other circuits.

3) When checking the "refusal to trip" circuit breaker, except for general electrical faults that can be quickly eliminated (such as low control power supply voltage, poor contact of control circuit fuses, melt melting, etc.), for electrical or mechanical faults that are difficult to handle at the moment, dispatch should be contacted to make a decision to stop or switch to maintenance.

(3) Fault phenomenon: Mistripping fault of circuit breaker. The possible reasons and solutions are as follows.

There are two main reasons for circuit breaker tripping faults: electrical faults and mechanical faults.

The main types of electrical faults are as follows:

1) Protection misoperation or improper positioning, or current and voltage transformer circuit failure.

2) The insulation of the secondary circuit is poor, causing two-point grounding in the DC system (two-point grounding in the tripping circuit).

There are mainly the following types of mechanical failures:

1) The closing support bracket and opening lock buckle cannot be maintained, resulting in tripping.

2) When the first stage valve and check valve of the hydraulic mechanical circuit breaker have poor sealing and leakage, the oil should be supplied to the upper end of the second stage valve through the closing holding hole to maintain the circuit breaker in the closing position. However, when the oil leakage exceeds the supplementary oil amount, the pressure at the upper and lower ends of the second stage valve is already different. When the pressure at the upper part of the secondary valve is lower than the pressure at the lower part, the secondary valve automatically returns, and the return of the secondary valve will cause the high-pressure oil in the closing chamber of the working cylinder to leak, thereby causing the circuit breaker to "trip incorrectly".

The corresponding processing methods are as follows:

1) If the automatic tripping of the protective panel is caused by external vibration due to personnel accidental touch or operation, the cause of the switch fault should be eliminated and power should be immediately transmitted.

2) For other electrical or mechanical faults that cannot be immediately restored to power supply, the dispatch and relevant leaders should be contacted to explain the "false tripping" of the circuit breaker and to switch it to maintenance and handling.

(4) Fault phenomenon: Misclosing fault of circuit breaker. The possible causes and solutions are as follows.

The reasons for causing false closing are as follows:

1) Two points of DC grounding are used to connect the closing control circuit.

2) The automatic reclosing relay's moving contact is closed incorrectly, or other components are connected to the control circuit, causing the circuit breaker to close incorrectly.

3) If the coil resistance of the closing contactor is too low and the operating voltage is too low, it will cause the circuit breaker to "close incorrectly" when a momentary pulse occurs in the DC system.

4) The energy storage spring buckle of the spring control mechanism is unreliable. In the event of vibration (such as when a circuit breaker trips), the buckle may automatically release, causing the circuit breaker to close on its own.

The processing method is as follows:

1) The handle is in the "open/close position" and the red light flashes continuously, indicating that the circuit breaker has been closed, but it is a "misoperation".

2) The circuit breaker that was mistakenly closed should be opened.

3) For circuit breakers that have been "mistakenly closed", if the circuit breaker is opened and then "mistakenly closed" again, the circuit breaker should be closed, and the electrical and mechanical reasons should be checked separately. The dispatch and relevant leaders should be contacted to stop using the circuit breaker and carry out maintenance.