There are many reasons for the overheating of the motor. The power supply, the motor itself, the load, the working environment and the ventilation and heat dissipation conditions can all cause the motor to overheat.

1. Power quality

(1) The power supply voltage is higher than the specified range (+5%), which makes the core magnetic flux density too large, increases iron loss and overheats; it also increases the excitation current, causing the winding temperature to increase.

(2) The power supply voltage is too low (-5%). When the load remains unchanged, the three-phase winding current increases and overheats.

(3) A phase is missing in the three-phase power supply, causing the motor to run in a missing phase and overheat.

(4) The three-phase voltage imbalance exceeds the specified value (5%), causing the three-phase power supply to be unbalanced and the motor to generate additional heat.

(5) The power supply frequency is too low, resulting in a decrease in motor speed and insufficient output, but the load remains unchanged, the winding current increases, and the motor overheats.

2. The motor itself

(1) The △ shape is connected into a Y shape or the Y shape is connected into a △ shape by mistake, causing the motor winding to overheat.

(2) Short circuit or grounding between phases or turns of the winding causes the winding current to increase and the three-phase current to be unbalanced.

(3) Some of the parallel branches of the windings are broken, causing an imbalance in the three-phase current and overloading and heating of the windings in the branches that are not broken.

(4) The stator and rotor rub against each other and generate heat.

(5) The cage rotor bars are broken, or the winding of the wound rotor is broken. The motor output is insufficient and it becomes hot.

(6) Motor bearing overheating.

3. Load

(1) The motor is overloaded for a long time.

(2) The motor starts too frequently and the starting time is too long.

(3) The towed machine fails, causing the motor output to increase or the motor to become stuck and stop rotating.

4. Environment and ventilation and heat dissipation

(1) The ambient temperature is higher than 35°C and the inlet air is overheated.

(2) There is too much dust inside the machine, which is not conducive to heat dissipation.

(3) The wind hood or wind shield inside the machine is not installed, and the air path is blocked.

(4) The fan is not installed or is damaged.

(5) There are too many missing heat sinks in the enclosed motor casing and the air duct of the protective motor is blocked.