Nine Common Causes of Motor Failure.

AIP shares with you the"Nine Common Causes of Motor Failure".

August 30, 2023

Nine common Causes of Motor Failure


Electric motors are ubiquitous in industrial environments and are becoming more complex and technical. All motors have a predetermined lifespan, typically 30,000 to 40,000 hours, however, this is dependent on proper maintenance - if not, The motor may fail more quickly. Understanding the causes of motor failures and taking action to reduce the risk of these failures will give your motor the best chance of achieving its maximum possible service life. There are three basic types of motor faults: electrical faults, mechanical faults, and electrical faults resulting from mechanical faults.

Nine common motor failure phenomena and their causes are as follows:

Ⅰ.motor won't start


① The power is not connected.

② Winding open circuit.

③ The winding is grounded or short-circuited between phases.

④ The wiring of the winding is wrong.

⑤ Melt blown.

Ⅱ.After the motor is connected to the power supply, the melt is burned off


①Single-phase start.

②The motor is overloaded or stuck.

③ The cross-sectional area of the melt is too small.

④ The connecting wire between the power supply and the motor is short-circuited.

Ⅲ.The motor does not start and hums after being powered on


① The motor is overloaded or stuck.

② The power supply is not fully connected.

③ The voltage is too low.

④ For small motors, the grease is hard or the assembly is too tight.

Ⅳ.Electric motor casing

Cause :

① The power line and the grounding line are wrong;

② The motor winding is damp and the insulation is seriously aging;

③ The lead wire and the junction box are grounded.

Ⅴ.The motor is difficult to start. After adding the rated load, the motor speed is lower than the rated speed

Cause :

① The power supply voltage is too low.

② The △ connection winding is wrongly connected to the Y connection.

③ The cage rotor is welded or broken.

④ Too many turns when rewinding.

Ⅵ.low insulation resistance


①The winding is damp or wet by water.

② Winding insulation aging.

Ⅶ.There is abnormal noise when the motor is running


①Bearing wear and failure.

② The iron core of the stator and rotor is loose.

③ The voltage is too high or unbalanced.

④ The bearing lacks lubricating grease.

⑤ The fan hits the windshield or the air duct is blocked.

⑥ The air gap is uneven, and the stator and rotor rub against each other.

Ⅷ.Motor overheats or smokes


① The power supply voltage is too high so the magnetic flux density of the iron core is oversaturated.

② Cause the temperature of the motor to rise.

③ The power supply voltage is too low, and the temperature rise of the motor is too high under the rated load.

④ Stator and rotor cores rub against each other.

⑤ The motor is overloaded or the mechanical resistance of the dragging production is too large, which makes the motor heat up.

⑥ The motor starts frequently or the number of positive and negative rotations is too much.

⑦ Fan failure, poor ventilation.

Ⅸ.When the motor is running without load, the current is unbalanced and the difference is large


① The power supply voltage is unbalanced.

② There is a fault in the winding, such as a short circuit between the surge, the reverse connection of a certain group of coils, etc.

③ When rewinding, the number of surges of the three-phase winding is uneven.

For various faults that may occur in the above motors, an AIP motor tester can be used. AIP focuses on global motor testing and provides intelligent equipment such as motor stator testing, motor testing, die-cast rotor testing, armature rotor testing, and dynamometers, etc, At present, AIP motor testing equipment has been used in household motors, water pump motors, electric tool motors, automotive motors, industrial motors, servo motors and other fields. AIP has served more than 13,000 customers worldwide, serving more than 60 countries, and the world There are more than 15 after-sales service centers.

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