The motor is our common electrical equipment, so how can we simply measure the quality of the motor? The motor is the electrical equipment that we often come into contact with, and it is also the basic equipment. We are mainly talking about three-phase motors here.

1. Multimeter

1. Adjust to the Ω × 1 gear to test and judge the resistance. The operations are as follows:

① Measure whether the motor is leaking. Measure the resistance between the three wires and the case (the contact between the test leads and the case should be good). If the resistance value is ∞, then the insulation of the winding coil is good. Otherwise, the motor leaks electricity.

② Measure whether the motor winding coil is open circuit. The three wires are measured in pairs. If one of the resistance values ??is ∞, then at least one group of the winding coils is disconnected.

③ Measure whether the motor coil is short-circuited between turns. The three wires are measured in pairs, if the resistance value of the three measurements is the same, then the motor is good, and it can be determined that the motor is a three-phase motor.

④If the measured three resistance values ??R, R′, R″, and R=R′+R″, then the motor is good, and it can be determined that the motor is a single-phase motor, and can also determine the main motor of the single-phase motor. Secondary winding and center tap.

⑤ If the measurement result does not match the situation of ③ or ④, or the measured value is 0, then the coil is short-circuited between turns, that is, the motor is broken.

2. Under normal circumstances, when it is determined that there is no problem with the power supply, the motor cannot be started. Use a multimeter to turn on the ohm gear. The red test lead is connected to one terminal of the motor, and the black test lead is connected to the other terminal of the motor. (When making measurement judgments, disconnect the power supply line to avoid interfering with the results) If there is resistance (small resistance) measured, it means that the coil is good; if the resistance value is 0, it means that the motor coil is short-circuited (phase-to-phase short-circuit). To measure the grounding, use one end of the multimeter pen to measure a random terminal of the motor, and the other end to measure the outer casing of the motor. If the resistance of the multimeter is zero, it means that the motor is grounded (phase-to-ground short circuit).

2. If the multimeter cannot be used to confirm, then we can only use the shaker. Before using the shaker, we need to check the open circuit and short circuit of the shaker.

1. Open circuit inspection:

Before the shaker is connected to the measured resistance, hang the end buttons L and E, shake the handle to make the generator reach the rated speed of 2r/s (2 revolutions per second), the pointer of a good watch should point to the scale " ∞” position.

2. Short-circuit inspection: short-circuit the terminal buttons L and E, slowly shake the handle, and the pointer of a good watch should point to the "0" position of the scale.

3. When the shaker is normal, measure the interphase resistance: connect the terminal buttons L and E of the shaker to the terminals of any two phases respectively, slowly shake the shaker, the normal motor, the interphase resistance should be around 0 , and the resistance between any two phases should be close.

4. Measure the phase-to-earth resistance: connect the end button L of the shaker to the phase wire terminal, and E to the motor shell. The resistance value of the shaker should be greater than 2MΩ, and it should also be greater than 0.5MΩ in a humid environment, and the resistance value between the shaker and the ground should be greater than 5MΩ. If it is lower than 0.5Ω, it is abnormal performance. Even if it can be used, it will not last long, and the insulation is not enough.