In our daily electromechanical maintenance, we sometimes encounter the first-level circuit breaker tripping that is supposed to use electrical equipment, but why the upper-level or next-level circuit breaker trips? The following author analyzes the reasons for everyone.
If the upper-level circuit breaker skips tripping, if it is found that there is a shunt protection action, but the shunt circuit breaker has not tripped, the circuit breaker of this level will be opened, and then the upper-level circuit breaker will be restored.
If it is found that none of the shunt protections have been activated, check whether the equipment within the power outage range is faulty. If there is no fault, close the upper-level circuit breaker and try to send each shunt circuit breaker one by one. When the power circuit breaker trips again when it is sent to a branch, it can be determined that the circuit breaker is a fault circuit breaker. The line can be isolated for maintenance and replacement.