The multimeter realizes the inspection method of the number of motor poles
How to judge the speed of a motor without a nameplate without a tachometer and the motor cannot be disassembled?
The speed of the motor is related to its number of poles, so as long as you know the number of poles of the motor, you can roughly know the speed of the motor.
All you need is a multimeter.
Inspection Method:
① Separate the six leads of the motor, adjust the multimeter to the ohm gear, and find the head and tail leads of any phase winding;
②Turn the multimeter to the lowest level of milliampere, and connect the test lead to the winding lead of the phase just found;
③ Rotate the rotor of the motor for one week, and observe the hand of the multimeter swinging several times. If it is one time, it means that the positive and negative current changes for one week, and it is a two-pole motor; in the same way, twice is a four-pole motor; three times is a six-pole motor.
The number of poles of the motor can be judged by rotating the rotor of the motor once and the pointer of the milliampere oscillates, so that the synchronous speed of the motor can be judged.
According to the synchronous speed formula of the motor, n=60f/p (n—the synchronous speed of the motor; f—the frequency of the power supply; p—the number of pole pairs of the motor). When the power frequency is 50hz, the synchronous speed of the two-pole motor is 3000 rpm, and the four-pole motor is 1500 rpm.
