Some reasons and solutions of motor heating
1. If the bearing is not working properly, it must cause the motor to heat up. Whether the bearing is working properly or not, we can be judged by hearing and temperature experience.
A hand or thermometer can be used to check whether the temperature of the bearing is in the normal range, or to hear the rod (copper rod) to contact the bearing box. If the impact sound, it means that there may be one or several ball crush. If there is a hissing sound, it means that the lubricating oil of the bearing is insufficient, and the motor should be operated for about 3,000 hours to 5,000 hours to change the grease.
2. The power supply voltage is on the high side, the excitation current is increased, and the electric opportunity is overheated.
Excessive voltage will endanger the insulation of the motor, so that it is in danger of being broken down. When the power supply voltage is too low, the electromagnetic torque will decrease. If the load rotation distance does not decrease and the rotor rotation number is too low, the increase of the slip rate will cause the motor to overload and heat, and the long time overload will affect the life of the motor. When the three-phase voltage is asymmetrical, that is, when the one-phase voltage is on the high or low side, it will lead to the excessive current of a certain phase, the heating of the motor, and the decrease of the rotation distance will make a "buzzing" sound, which will damage the winding for a long time.
In a word, whether the voltage is too high, too low or asymmetrical voltage will increase the current, the motor heating and damage the motor. Therefore, according to the national standard, the change of motor power supply voltage should not exceed ±5% of the rating, and the output power of the motor can be maintained. The power supply voltage of the motor should not exceed ±10% of the rated value, and the difference between the three-phase power supply voltage should not exceed ±5% of the rated value.