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The biggest cognitive misunderstanding of electric motor protector

“The motor protector is useless! Why else would my motor burn out if it had a protector?!”

Facing this kind of doubt, can only ask helplessly, “you, is there any misunderstanding to the motor protector?”


There are many reasons that cause the motor to burn out during operation. Environmental factors, the quality of the motor itself, unstable field voltage and current, improper operation of the staff, may cause motor failure, or even burn out. The work of the motor protector, is to detect whether the current is abnormal, to determine whether the output signal, cut off the power supply, open the protection measures. Therefore, it is not necessary to say that after installing the motor protector, it is 100% guaranteed that the motor will not burn out. The motor protector can only protect the motor when the current is abnormal. In other words, the motor protector can only help you avoid some of the factors that cause the motor to burn out, but not all.


Common causes of motor burn out can be classified into two major categories: mechanical failure and electrical failure. Mechanical failure is actually caused by the motor itself. For example, motor bearing problems, stator and rotor fit gap problems, wiring problems; Electrical fault, common is over – current, over – voltage, three – phase imbalance. Of course, in addition to these two categories, the long-term overload operation of the motor will also lead to burn out, the motor working environment is not good will also lead to burn out, the protection device does not match will also lead to burn out……


The reason why the motor protector is installed is that the motor will still burn out. We can start with the following analysis:

1.The parameters of motor protector purchased do not correspond to the equipment;

2.The protection function of the purchased motor protector is inconsistent with the actual protection required;

3.The accuracy of the purchased motor protector does not reach the actual required protection level;

4.The motor burn out is not an electrical fault, but something else.


Therefore, before the purchase of motor protector, please clearly determine the cause of the fault of your equipment, and then choose the appropriate protector according to the actual needs of your equipment protection function, protection level accuracy, equipment parameters and other conditions. The right medicine is very important!

Post time: Nov-08-2019
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