Fault and treatment of single-phase asynchronous motor

The asynchronous motor with single-phase AC power supply is called single-phase asynchronous motor. Because it only needs single-phase AC, single-phase asynchronous motor is convenient to use and widely used, and has the advantages of simple structure, low cost, low noise and low interference to radio system. Therefore, it is often used in household appliances and small power machinery with low power, such as electric fan, washing machine, refrigerator Air conditioning, range hood, electric drill, medical equipment, small fan and domestic water pump, etc. Common fault diagnosis and treatment of single-phase motor:

1. The power supply voltage is normal, and the motor does not start after power on.

1) The power wiring is open circuit (the motor is completely silent). There shall be no voltage at both ends of the measuring terminal.

2) Open circuit of main winding or auxiliary winding. The open circuit can be determined by measuring the DC resistance.

3) The contact of centrifugal switch is not closed, so that the auxiliary winding cannot be energized. Disconnect the connection point between the main winding and the auxiliary winding, and then determine it by measuring the DC resistance, or by the method in part II.

2. The power supply voltage is normal. After power on, the motor rotates at low speed, with "buzzing" sound and vibration, and the current does not drop.

1) The load is too heavy.

2) The motor stator and rotor rub against each other. It will make an abnormal friction sound.

3) The bearing is stuck due to poor bearing assembly, oil consolidation in the bearing, bearing roller support or roller damage, etc.

3. After power on, the power fuse will blow quickly

1) The winding turns are seriously short circuited to ground. Measure the DC resistance. If the value is far less than the normal value, it is an inter turn short circuit of the winding; In case of serious short circuit to ground, the insulation resistance meter or multimeter can be used with higher resistance (such as R × 1K gear). The current will be greater than the rated value.

2) The outgoing phase line of the motor is grounded. The inspection method is the same as fault item 1).

3) The capacitor is short circuited. Use a multimeter to lower the resistance (e.g. R × Gear 1) measure the DC resistance between the two ends of the starting winding circuit (including capacitor and starting winding, excluding centrifugal switch).