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Selection of circuit breakers for motor protection

Promulgator : TAIXIDate : 2017-02-16Views : 177

There are two different ways of using the circuit breaker for motor protection. One is to control the motor in series with the other switchgear (such as knife switch, contactor, etc.), that is, the circuit breaker is only short circuit, overload or under voltage protection. , The normal operation by other electrical commitment; the other refers to the circuit breaker is no longer in series with other switching appliances that play a protective role, but also for the use of less frequent operation switch. For the latter case, the operating conditions and life expectancy need to be considered.

Motor protection circuit breakers are generally selected according to the following principles:

1, long time action current setting value should be equal to the motor rated current value. The following are the same as the "

2, for the protection of cage motor circuit breaker, the instantaneous setting of the current should be equal to 8 to 15 times the motor rated current. As for the size of the value depends on the motor model, capacity and starting conditions.

3, for the protection of the winding rotor motor circuit breaker, the instantaneous setting current should be equal to 3 to 6 times the motor rated current. Similarly, the size of the decision with the motor model, capacity and starting conditions.

The return time of the 4,6x long delay current setting should be greater than or equal to the actual starting time of the motor. Depending on the severity of the load at start-up, a value of 1, 2, 5, 8, 15s is available.

Tesi Electric independently produced DZ47-125 miniature circuit breaker, can be short-circuit or overload the motor quickly cut off the electrical lines, with strong reliability, fast tripping, breaking capacity, small and beautiful and so on.