Causes of electric motor failure

Electric motor is an essential electrical device in the home and industries. 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.

To resolve the problem, the motor should be inspected regularly and other maintenance activities need to be performed to ensure efficient operation

Causes of motor failure:

There are six main causes of electric motor failures:

  • Over-Current
  • Low Resistance
  • Overheating
  • Dirt
  • Moisture
  • Vibration

Over current:

In different operating conditions, electrical devices sometimes begin to consume more current than their total capacity. This unpredictable event will happen very suddenly and will greatly impact the engine.

To avoid 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 installation of the motor, it is observed that the insulation resistance is more than one thousand mega ohms.

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 insulation performance is monitored at regular intervals.


Excessive heat in the motors can cause several performance problems. Overheating causes the winding insulation of the motor to deteriorate rapidly. For each ten degree centigrade increase in temperature, the lifetime of the insulation is reduced by half. It has been concluded that more than 55% of insulation faults are caused by overheating.

Overheating can occur due to bad current value to the motor and also occurs when an electric motor is forced to operate in a high-temperature environment. The area where the electric motors operate must have an adequate cooling system and a ventilation system


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 from dirt.


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.


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.


Instrumentation Engineer

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