How to check the common faults of the washing machine motor

Fault inspection of AC asynchronous motor
1. Listen to the sound and carefully find the fault point. During the operation of the AC asynchronous motor, if a fine "hum" sound is found, there is no change of high and low, it is a normal sound, if the sound is thick and sharp. "Buzzing" and "hissing" sounds are signs of failure and should be considered for the following reasons:
(l) The vibration of the iron core loosening motor during operation, and the temperature fluctuations will cause deformation of the iron core fixing bolts, resulting in the loosening of the silicon steel sheet, resulting in large electromagnetic noise.​
(2) Rotor noise The sound of the rotor rotating, produced by the cooling fan, is a kind of "wheeze" sound, like the "dong dong" sound when drumming, which is the sudden start, stop, reverse connection of the motor. In the case of speed changes such as braking, the acceleration torque makes the cooperation between the rotor iron core and the shaft loose. The light ones can continue to be used, and the heavy ones can be disassembled for inspection and repair.​
(3) Bearing noise When the motor is running, you must pay attention to the sound culture of the bearing. Touch one end of the screwdriver on the bearing cover and the other end on the ear, you can hear the sound changes inside the motor, different parts, different faults, with different voices. For example, the sound of "crunching" is caused by the irregular movement of the roller gun in the bearing, which is related to the clearance of the bearing and the state of the grease. The sound of "hissing" is the sound of metal friction, which is generally caused by the lack of oil in the bearing. The bearing should be disassembled and greased.
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2. Use the sense of smell to analyze that the faulty motor has no peculiar smell in normal operation. If it smells strange, it is a fault signal, such as a burnt smell, which is emitted by the barbecue of the insulating material, and with the increase of the temperature of the motor, it is serious. It will also emit smoke; such as oil coke smell, most of the bearing is lack oil, and the odor of oil and gas evaporation occurs when it is close to the dry grinding state.
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3. Use the hand feels to check the fault. Touch the casing of the TV with your hand, and you can roughly judge the temperature rise. If you touch the casing of the motor with your hand, you will feel very hot and the temperature value is very high. You should check the reasons, such as overload, voltage too high, etc., then troubleshoot the cause.​

Causes of common failures
1. The motor has no starting torque, or cannot be started at no-load, and makes an abnormal sound. reason:
(l) One phase of the three-phase power circuit (including the knife switch and the lead stator winding) is powered off, resulting in a single-phase start-up.​
(2) The power supply voltage is too low.​
(3) Excessive wear of the bearing makes the rotor close to one side of the stator, causing the stator and the rotor to be non-concentric and the air gap to be uneven.​

2. The starting torque of the motor is small, and it cannot be started when there is a load. When the load increases, the motor stops, sometimes making a strong noise and local heating. Reasons: The grid voltage is low, the windings are short-circuited between turns, the rotor windings are disconnected or de-soldered, and one-phase disconnection after starting causes single-phase operation.​

3. The starting current is large, unbalanced, and loud, causing the protection device to act and cut off the power supply. Reason: The wiring method of the stator winding may be incorrect, and the insulation of the winding to the ground is aging.