What is the difference between a multimeter resistance and a beeper when measuring on/off?
Multimeter resistance file can measure the specific size of the line resistance, and then we can analyze the resistance size to determine whether the line is normal or what faults exist.
The buzzer can only determine whether the line resistance is large or small (generally about 30-50Ω as the cut-off point, different multimeters vary a little).
Assuming that the multimeter beeping gear beeping critical resistance value of 50 Ω, then when the line or load resistance is less than 50 Ω, the beeping gear will sound, and the smaller the resistance, the greater the beeping sound. But when the line or load resistance is greater than 50Ω more, the beeper will not ring. So when the line resistance is greater than 50Ω or ∞, we use the buzzer gear is no way to distinguish.
Single-phase motor good or bad judgment
Know from the title of the motor has a total of 4 lines, then we can speculate that the motor should be a single-phase motor (specifically what type of single-phase motor to see the physical in order to draw conclusions).
Single-phase motors have two coil windings, a start winding and a run winding. Because of the thicker coil of the running winding and the thinner coil of the starting winding, the resistance value of the starting winding is larger than that of the running winding. That specific resistance size and motor type, power related, more than ten ohms to one or two hundred ohms are possible. (The higher the motor power, the lower the resistance; the lower the power, the higher the resistance)
If the motor power is very small, then its resistance value will be very large, if the resistance value is greater than 50Ω, we use the buzzer file to measure the results is not ringing. Similarly, if the motor winding is burned out, then we use the buzzer gear will not ring.
If the motor power is large, then its resistance value will be small, if the resistance value is less than 50 Ω, we use the buzzer gear measured results is a beep. Similarly, if a short circuit occurs in the middle of the winding of the motor, then we use the buzzer gear to measure the result is also a beep.
So there's really no way to tell if the motor is good or bad in the situation you're describing. To determine whether the motor is good or bad, you need to analyze the motor resistance and power size.
For just contact with the multimeter electrician friends, I suggest that you use the multimeter to measure the line or load, try to use the resistance file rather than the beeping file, which is very helpful for maintenance and mastery of the multimeter. Only after you have mastered the application of multimeter resistance measurement, then use the buzzer gear to improve the speed of repair.
