15 Reasons for Excessive Temperature Rise of Motors

2024-09-20

During the operation of a three-phase motor, there are various reasons for excessive temperature rise. Only by finding the correct cause can a thorough and effective troubleshooting be carried out. Today, the following 15 reasons for excessive temperature rise of the motor are summarized:

Interturn or interphase short circuit or grounding of the stator winding increases the current and the copper loss, resulting in overheating. If the fault is not serious, only rewrapping the insulation is needed. In severe cases, the winding should be replaced.
Open circuit of one phase of the stator winding or disconnection of a certain branch in a parallel winding causes unbalanced three-phase current and overheats the winding.
Broken bars of a squirrel-cage rotor or loose connections of winding rotor coils cause excessive current in the maintenance network and overheating. Copper bar rotors can be repaired by welding or replaced. Cast aluminum rotors should be replaced.
Damaged or excessively worn bearings cause the stator and rotor to collide and rub. Check whether the bearings are loose and whether the stator and rotor are poorly assembled.
Excessive load. Reduce the load or replace with a motor of higher power.
Faults in the driven mechanical equipment cause overload. Check the driven machinery and eliminate the faults.
Excessive starting frequency. Reduce the number of starts.
The operating environment temperature is too high (exceeding 40°C), making the three-phase inlet air too hot and difficult to dissipate heat. Cooling measures should be taken.
Too much dust and oil inside and outside the motor affect heat dissipation. Dust and oil should be removed.
The motor air duct is blocked, ventilation is poor, and the air intake is reduced. Remove debris and dirt from the air duct opening.
The internal fan of the motor is damaged, installed incorrectly or not installed. It should be installed correctly. Damaged fans should be repaired or replaced.
When the voltage exceeds 10% above the rated voltage of the motor or is lower than 5% of the rated voltage of the motor, the motor is prone to overheating under rated load and the temperature rise increases. The manufacturer of Dalan Motor suggests that everyone should check and adjust the voltage.
When the unbalance degree of the three-phase power supply voltage between phases exceeds 5%, it causes unbalanced three-phase current and additional heating of the motor. The voltage should be adjusted.
A fuse is blown or the power switch has poor contact, resulting in single-phase operation and overheating. Damaged components should be repaired or replaced.
There is an error in the wiring of the three-phase motor winding. Wrongly connecting in star instead of delta or wrongly connecting in delta instead of star will cause the motor to overheat when operating under rated load. Check and correct it.