Using a multimeter to determine whether a motor is good or bad
Motors include three-phase motors and single-phase motors, and single-phase motors have three wires and six wires.
three phase motor
Three-phase motor three-phase winding 6 taps. We start by removing the connecting piece that connects to the motor terminal. Use a multimeter to measure the first and last ends of each phase winding to see if it is on or off. Then use a multimeter to measure the resistance value between each two-phase winding, at least greater than 0.5 megohm, the bigger the better. Finally, measure the insulation resistance of each phase winding and the motor casing, which should also be infinite. This measurement can basically judge the quality of the three-phase motor.
Unidirectional motors have only two windings, a start winding and a run winding. One of the three wires is their common wire, that is, one end of the two-phase winding is connected together. The other two are another tap of the two-phase winding.
The resistance between the two taps should be maximum and equal to the sum of the resistance values of the two windings.
Of course, we also need to measure the resistance of the coil and the casing to see if it has been broken down. Of course, the larger the resistance, the better, and the minimum is the same, not less than 0.5 megohms.
6 wire single phase motor
The reason why there are 6 wires is actually two wires (Z1, Z2) are the wires of the centrifugal switch. This kind of motor also has 6 terminals, so its connecting piece should also be removed. The capacitor is also removed, and then measure the resistance at the beginning and end of the two-phase windings and between the two-phase windings. The method is the same as that of a three-phase motor.
Judging the quality of the motor with a multimeter can only be a preliminary judgment. The insulation resistance between the windings and the insulation resistance of each phase winding to the ground should be measured with a megohmmeter to be more accurate.
In addition, the short circuit between the turns of the winding cannot be measured. We can only use the method of comparison to guess whether there is a short circuit between the turns. For example, the organization of a certain phase winding is much smaller than that of the other two phases, then we can suspect that there is a short circuit between turns.
