What is the reason of motor current overload?

What is the reason of motor current overload?

1, low supply voltage

When the mechanical load is constant, the power supply voltage decreases, which will cause the working current of the motor to increase. As the working current of the motor increases, the temperature of the motor will also increase. If the overload time is long, the motor temperature will exceed the allowable temperature and burn out. The actual work shows that the service life of the motor will be reduced by half every time the actual working temperature exceeds the allowable temperature of 8℃.

2. Frequent startup

The starting current of asynchronous motor is 5 ~ 7 times of normal working current. If the motor is started frequently, the motor temperature will rise. Conveyors and shearer in underground mining face are prone to this overload phenomenon.

3. Long startup time

Starting with load often leads to long starting time and high motor temperature overload. For example, the working face conveyor is full of coal, and then starting the motor will get stuck and start for a long time.

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4. Mechanical blockage

Because the motor bearing is damaged, the rotor is stuck, or the load dragged by the motor is stuck, the motor will overload.

Causes of overload of asynchronous motor

1, caused by the towed mechanical equipment. For example, the waterway of irrigation and drainage machinery is blocked and the shafts are not concentric, which leads to excessive load or even blockage of the motor.

2. Due to the poor working conditions of the motor itself. Such as poor ventilation, high ambient temperature, motor mechanical failure and other reasons caused by overheating, lower insulation level, or even short circuit.

3. Due to the poor quality of the power supply network, such as low voltage and three-phase imbalance, the motor current increases.