Comparison of motor protector and low-voltage circuit breaker
Function of motor protector
1, Compensation of ambient temperature (temperature change does not affect the original rated positive parameters).
2, Flexible rated current adjustment function (wide applicability, can adjust parameters flexibly according to the actual condition of the motor).
3. Loss of phase protection function (Now the motor protector has various current protection functions, and the response speed is faster.
4. There is a hand/self-reset protection function, which can be selected flexibly.
The above-mentioned low-voltage circuit breakers with various functions are not available. In addition, the overload protection of low-voltage circuit breakers is mainly used for line overload protection, and the overload tolerance coefficient is large. The motor overload tolerance factor is small.
Differences in protection objects
The protection object of the circuit breaker is the cable, and the protection object of the motor protector is the motor
1. The level difference of the circuit breaker is generally large.
2. The operating characteristics of the circuit breaker are not as sensitive as the motor protector.
3. The motor protector has protection functions such as open phase and unbalance (realized by disconnecting the contactor coil).
The main reason is that under normal circumstances, the circuit breaker cannot accurately protect the motor.
If the peak value of the starting current can be avoided, the overload protector often cannot achieve accurate protection of the motor (the setting value is too large).
Therefore, generally only the circuit breaker is used for short-circuit protection. The motor protector is used to protect the motor from overload, phase loss and unbalance. In this way, the above two contradictions can be avoided.
The circuit breaker is tripped.
The motor protector is to cut off the control circuit twice.