What causes electric motors to overheat and burn?
1. The reason why the electric motor runs weak, has a burning smell
Causes and handling of damage to electric motor windings – asynchronous motor
According to statistics, about 85% of problems when operating electric motors – three-phase asynchronous motors used in production are electrical problems due to coil fires, and about 15% are caused by mechanisms and other faults. .
– The cause of the coil fire is mainly due to the operation when the power source is out of phase or overloaded, the coil ground is touched and the short circuit between the phases of the coil.
The second is mechanical causes such as friction between the stator and the rotor.
Here, we focus on analyzing the cause of the electric motor – motor winding fire fault from an electrical perspective and propose corresponding handling methods.
– 3-phase motor operates when there is a phase loss. Electric motor failure – the motor cannot start, even at no load, the speed is slow and there is a sound, the electric motor emits smoke and heat, accompanied by a burning smell.
Corrective check: Remove the motor-motor end cap, you can see 1/3 or 2/3 of the terminal phase windings at the end of the windings are scorched or dark brown.
– The contact of the switchgear supplying the electric motor – the motor has poor contact or mechanical damage resulting in the fuse of a certain phase being blown.
– The specification of the three-phase switch in the electric motor-motor power supply circuit is different and it has a small capacity to break.
How to fix: Should be replaced with a fuse of the same specifications according to the capacity of the electric motor – motor.
– The switching devices in the electric motor-motor power supply circuit and the contactor contacts are in poor contact (burnt or loose).
How to fix: Repair and adjust dynamic and static contacts for better contact.
– Phase break of one of the power supply lines.
The fix: Find out where the broken wires are and connect them securely.
– The contact between the windings of the electric motor – the motor has poor contact.
How to fix: Double check the wires connecting the electric motor – motor windings and solder them firmly.
2. The reason why the electric motor does not run hot due to overload
– The phenomenon of electric motor – motor current exceeds the rated value, the temperature of the electric motor exceeds the rated temperature rise.
How to fix: Check the three windings of the electric motor – the motor is all burnt, the bearings are not dry, the stator core and the rotor are rubbing against each other.
When the motor is overloaded, it is necessary to consider appropriate reduction of the load or replace the electric motor – the motor has the appropriate capacity.
– If the supply voltage is too high or too low, a three-phase power supply voltage stabilizer should be installed.
– Electric motor – motor has been wet or corroded for a long time by corrosive substances, the insulation resistance decreases. According to the specific situation, overhaul or replace the electric motor according to the same capacity and specifications.
– Motor bearing with dry grease, excessive wear or mechanically misaligned rotor will cause the rotor of the electric motor – the motor to wind and the motor current to exceed the rated value.
How to fix: First of all, it is necessary to carefully check the wear condition of the bearing, if it is not qualified, it should be replaced with a new bearing. Second, the bearing must be cleaned and pumped with an appropriate amount of grease. Then check the end cap of the electric motor – motor, if the center hole of the end cap is worn and the rotor is not concentric, the end cap should be repaired or replaced.
– The transmission part of the mechanism is faulty, causing the electric motor – motor to overload and burn the coils of the electric motor – motor.
How to fix it: Check for errors in mechanical parts and take measures to solve them so that they can rotate flexibly.
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