1. Causes of circuit breaker false trip
There is no fault in the system once, and the main reasons for the circuit breaker false trip are:
(1) Secondary circuit failure. For example, if the DC link is grounded at two points, some components in the secondary circuit are poor in performance, damaged or short-circuited, and the secondary circuit is short-circuited due to insulation damage caused by moisture or corrosion of the cable or terminal.
(2) Personnel misoperation. If you accidentally misplace certain secondary components.
(3) The operating mechanism trips itself or the mechanism is faulty.
(4) The relay protection device malfunctions or protects the exit relay contact from being short-circuited, etc., causing the circuit breaker to trip erroneously.
2. Circuit breaker false tripping phenomenon
(1) When the circuit breaker trips, there is no phenomenon accompanying system impact, metering shock swing, sudden lighting darkening, abnormal equipment sound, etc., and no trace of fault on-site inspection.
(2) After the trip, the current meter and active and reactive meter indications of the circuit breaker circuit are zero.
(3) The fault record shows that each electrical parameter and waveform are not faulty.
3. Handling of circuit breaker false trip
(1) Record the signals and symbols that appear in a timely and accurate manner. According to the equipment and the secondary circuit, whether there is work, whether there is protection signal, the meter indication, the signal, the impact caused by the short-circuit current, the obvious fault phenomenon on the site, etc. Tripped.
(2) Check the circuit breaker and its operating mechanism, secondary circuit, etc., and analyze the cause of the false trip. After the circuit breaker is accidentally tripped, if the reclosing action is successful, it is not allowed to check the operation mechanism, protection device, secondary circuit, etc. of the circuit breaker, and only observe the situation, record signals and phenomena, and report the dispatch. In order to avoid accidental tripping of the circuit breaker again during the process.
(3) If the cause of the false trip is the secondary circuit failure or the operating mechanism problem, and the power transmission cannot be resumed immediately, the isolation switch on both sides of the false jump circuit breaker should be opened, and the load should be reversed to the standby power supply according to the dispatching command. Or power the load by means of reverse operation, etc., stop the circuit breaker and stop the safety measures. If there is no backup power supply and the operation mode cannot be reversed, after the deactivation check processing is completed, power is sent again or processed according to the scheduling command.
(4) If there is a protection action signal, it should be based on whether there is a shock caused by the short-circuit current, whether the voltage suddenly drops, whether the illumination suddenly becomes dark, whether there is a fault trace within and outside the protection range, and contact with the dispatch to understand the operation of the system. When there are conditions, it can be analyzed with the fault recording map to distinguish whether the fault protection action is incorrect, or if there is no fault and the protection misoperation causes the circuit breaker to trip. If the fault occurs outside the protection range, if the protection setting value does not match, etc., if the protection malfunction causes the circuit breaker to trip erroneously, the fault point should be isolated and then the power transmission should be resumed. If there is no fault, the protection device malfunctions due to damage of the protection device components, secondary circuit failure, etc., should check the protection device for obvious abnormal phenomena and report the dispatch, dump the load to the standby power supply, or use the reverse operation Modes and other measures to isolate the circuit breakers that have been accidentally tripped, and power off and repair them. For circuit breakers with multiple sets of protection, they should be handled in strict accordance with the site regulations or regulations. If there is some work on the protection circuit, the safety measures may not cause the circuit breaker to trip erroneously. The work on the protection circuit should be stopped immediately, and the safety measures should be taken to resume the power transmission.
(5) If the circuit breaker is accidentally tripped for human reasons, or other operations can be resumed immediately after the cause is found, the power transmission should be resumed according to the dispatching command. For the feeder line, the power can be turned on immediately. For the tie line, when there is power on the line, it must be closed by the parallel device or when there is no possibility of parallel connection.
(6) If the circuit breaker is accidentally tripped, the cause of the failure cannot be determined. The operating personnel should take measures to stop the power failure of the circuit breaker according to the dispatching requirements, and the special personnel should handle it.