Check and eliminate common faults of AC motor
In the operation of AC motors due to friction, vibration, insulation aging and other reasons, it is inevitable that the failure. If these faults are promptly inspected, discovered and eliminated, they can effectively prevent accidents.
One, asynchronous motor fault check
1. Listen to the sound and carefully find fault points. AC asynchronous motors are in operation. If you find a fine "click" sound, there is no change of height, it is a normal sound, if the sound is thick, and there is a sharpå—¡ å’å’ å’å’ å’å’ å’å’ å’å’ ã€ ã€ ã€ ã€ ã€ ã€ ã€ ã€ ã€ ã€ ã€ ã€ ã€ ã€ ã€ ã€ ã€ ã€ ã€ ã€ ã€ ã€ ã€
(l) Loosening of the iron core during operation of the motor, changes in temperature will cause the iron core fixing bolts to deform, causing the silicon steel sheet to loosen and generate large electromagnetic noise.
(2) Rotor noise The sound produced by the rotation of the rotor, generated by the cooling fan, is a kind of "click" sound, like the "click" sound when the drum is beaten, which is the sudden start, stop and reverse connection of the motor. In the case of brakes and other variable speeds, the acceleration torque causes the rotor iron core to loosen with the shaft, lighter ones can continue to use, and the others can open inspections and repairs.
(3) Bearing noise During operation of the motor, attention must be paid to the culture of bearing noise. Touch the end of the screwdriver on the bearing cover and the other end to the ear. You can hear the internal sound of the motor, different parts, and different faults. There are different voices. Such as "click" sound is generated by the irregular movement of the roller inside the bearing, it is related to the bearing clearance, grease status. The "click" sound is a metallic friction sound, which is generally caused by the lack of oil in the bearing. It should be dismantled and the bearings should be greased.
2. Use the sense of smell to analyze the faulty motor in the normal operation is no odor, if you smell the difference, it is a fault signal, such as Jiaozhewei, is issued by the insulation barbecue, and with the increase in the temperature of the motor, serious Smoke; such as oil smell, most of the bearing is lack of oil, near the dry grinding state of oil vapor odor.
3. Using the touch, check the fault Touch the shell of the TV with your hand, you can roughly determine the level of temperature rise, if you touch the motor shell with a hand and feel hot, the temperature value is high, you should check the reasons, such as: overload, high voltage , and then troubleshoot the cause.
Second, the cause of common failures
1. The motor has no starting torque, or it cannot start when no load is present, and it makes an abnormal sound. the reason:
(l) Three-phase power circuits (including knife switches and lead stator windings) have a phase disconnect and cause single-phase startup.
(2) The power supply voltage is too low.
(3) The excessive wear of the bearing causes the rotor to approach one side of the stator, causing the stator and rotor to be of different concentricity and uneven air gap.
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, and sometimes a strong noise is generated and the part is heated. Causes: The grid voltage is low, the windings have short circuits in the turns, and the rotor windings are broken or disconnected. After the start-up, one-phase breakage causes single-phase operation.
3. The starting current is large and unbalanced and the sound is loud, causing the protection device to operate and cut off the power supply. Cause: The stator winding wiring method may not be correct and the windings are insulated against the ground.
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