electric motor overload

Motor overload is a general motor having a fixed running power. It is called rated power. The unit is Watt (W). If in some cases, the actual power of the motor exceeds the rated power of the motor, it is called motor overload.

Circuit principle

There is a thermal relay in the main circuit (motor overload protection), when the motor is overloaded, the thermal relay normally closed contact, cut off the control circuit, normally open contacts on light, the overload is removed, there are two kinds of thermal relay contacts reset the circuit in the form of restart: manual reset: press reset automatic reset button; overload removal, wait a minute, it automatically recovered after cooling.

If you are in the manual reset position, after finding the thermal relay, press the red handle above, and you can hear a "snap" sound.

Overload symptom

1. motor heat increase;

The speed of the 2. motor decreases, and it may even drop to zero.

3. motor has low sound, vibration is general.

4. if the load changes sharply, the motor speed will be high and low.


1. electrical reasons: such as missing phase, voltage exceeding allowable value and so on;

2. mechanical reasons: such as excessive torque, motor damage (bearing vibration) and so on;