What are the causes of excessive motor temperature?

There are many reasons for the high temperature of the motor. The power supply, the motor itself, the load, the working environment and the ventilation and heat dissipation can all cause the motor to overheat. The bearings are only one factor that causes the motor to overheat.

1. Power supply quality

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

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

(3) The three-phase power supply is missing a phase, and the motor runs in the missing phase and overheats.

(4) The three-phase voltage imbalance exceeds the specified range (5%), which causes the three-phase power supply to be unbalanced and the motor to heat up extra.

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

2. The motor itself

(1) The motor winding is overheated when the triangle is connected to the Y shape or the Y shape is connected to the triangle shape by mistake.

(2) The winding is short-circuited or grounded between phases or turns, resulting in increased winding current and unbalanced three-phase current.

(3) Some branches in the parallel winding branches are broken, causing unbalanced three-phase current, and the winding of the unbroken branches is overloaded and heated.

(4) The stator and rotor rub and heat up.

(5) The squirrel cage rotor bars are broken, or the winding of the wound rotor is broken. The motor output is insufficient and heats up.

(6) The motor bearing is overheated.

3. Load

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

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

(3) The driven machine fails, causing the motor output to increase or it is stuck and cannot rotate.

4. Environment and ventilation and heat dissipation

(1) The ambient temperature is higher than 35"C, and the air intake 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 on the enclosed motor housing, and the protective motor air duct is blocked.