Causes of Electric motor failure

Electric motors are commonly used field instrument for household uses and industrial purposes. In general, in large organizations, an engine maintenance program is carried out in which the causes of the engine failures are identified and the necessary measures are taken to avoid them or reduce their impact.

Motors must be inspected regularly, and other maintenance activities must be performed to ensure efficient operation. Here, we studying the causes of motor failure.

Common Causes of Electric Motor Failures:

  1. Over-Current

  2. Low Resistance

  3. Overheating

  4. Dirt

  5. Moisture

  6. Vibration

Over-Current (Electrical Overload):

electrical devices sometimes begin to consume more current than their total capacity. This unpredictable event will happen very suddenly and will have a big impact on the devices.

To avoid the excessive current, there are some devices that must be installed that can prevent it from happening. These devices are usually wired into the circuits and will automatically turn off the additional amount of current flowing in the circuit.

Low Resistance:

Most engine failures occur due to low insulation resistance. This problem is considered the most difficult to address.

In the initial stages of the motor installation, it is observed that the insulation resistance is more than 1000 megaohms. After a while, the insulation performance begins to degrade to an alarming level because the resistance begins to decay gradually.

There are automatic devices that test the insulation resistance from time to time and safeguard the installed rotating equipment that prevents such failures. It is important that the performance of the insulation is monitored at regular intervals.

Over Heating:

Overheating of motors can result in various other problems. Overheating causes the winding insulation of the motor to deteriorate rapidly. For each temperature increase of ten degrees Celsius, the life of the insulation is reduced by half. It has been concluded that more than 55% of insulation failures are caused by overheating.

Overheating can occur by several other factors, every motor has a design temperature. If a motor starts at a bad current value, it starts to operate in a condition much warmer than the design temperature.

Overheating also occurs when an electric motor is forced to operate in a high-temperature environment. This means that the speed at which the heat can be driven is reduced to an alarming speed. The area where electric motors operate must have an adequate cooling system and ventilation.


Dirt is one of the main sources that cause damage to electric motors. It can damage the motor by blocking the cooling fan, which causes the temperature to increase.

It can also affect the insulation value of the winding insulation if it sits on the motor windings. There are protective devices available that are used to protect the motor from dirt.


Humidity also affects the performance of electric motors. It contributes greatly to the corrosion of the motor shafts, bearings and rotors. This can lead to an insulation fault too. The inventory of engines must be kept dry at all times.


There are several possible causes of vibration, such as motor misalignment. Corrosion of parts can also cause the motor to vibrate. The motor alignment must be checked to eliminate this problem.

When unusual vibration occurs it means that the motor should be get to maintenance.

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