What is the difference between the multimeter resistance file and the buzzer file when measuring on-off
The buzzer can only judge whether the line resistance is large or small (generally around 30-50Ω is the cut-off point, and different multimeters are slightly different).
Assuming that the critical resistance value of the beeping sound of the multimeter's beeping gear is 50Ω, the beeping gear will only sound when the resistance of the line or load is less than 50Ω, and the smaller the resistance, the louder the beeping sound. But when the line or load resistance is more than 50Ω, the buzzer will not sound. So when the line resistance is greater than 50Ω or ∞, we can't tell it with the buzzer.
Good or bad judgment of single-phase motor
Knowing from the topic that the motor has a total of 4 wires, then we can infer that the motor should be a single-phase motor (the specific type of single-phase motor can only be concluded by seeing the real thing).
If the power of the motor is small, then its resistance will be very large. If the resistance is greater than 50Ω, the result we measured with the buzzer file is that there is no sound. Similarly, if the motor winding is blown, it will not sound when we use the buzzer to test.
If the power of the motor is large, its resistance value will be very small. If the resistance value is less than 50Ω, the result we measured with the buzzer file is a buzzing sound. Similarly, if there is a short circuit in the middle of the motor winding, then we will also have a buzzing sound when we use the buzzer file to measure the result.
