Type of circuit breaker for three-phase induction motor

Although there are many types of motors, many mechanical equipment will choose three-phase induction motors to drive the machinery and equipment to maintain stable operation with their good performance. In order to prevent the electrical operation of the motor from being disturbed by surrounding adverse factors, resulting in serious problems such as motor short circuit, in addition to the appropriate motor model, it will be equipped with a special circuit breaker for protection.

Since the motor current of each specification is different, the circuit breaker must also be selected, otherwise it will play a negative role. In terms of tripping mode, there are two kinds of circuit breaker: short-circuit tripping and thermal tripping. The former refers to that the huge current generated by short-circuit fault in the circuit makes the short-circuit release act quickly to disconnect the circuit and achieve the purpose of protection; The latter is when the current in the circuit exceeds the rated current of the circuit breaker.

Although the current when the motor starts is relatively large, as long as the existence time of the impulse current at the moment of motor start is less than the action time of the circuit breaker, the circuit breaker will not act and can not reach the action point of the short-circuit release. At this time, the thermal release just conforms to this characteristic, because it also needs a certain time, which is enough for the motor to complete the start.