What is the difference between resistance mode and buzzer mode when measuring continuity?
The resistance range of a multimeter can measure the specific resistance of the line, and then we can analyze and determine whether the line is normal or has any faults based on the resistance.
The buzzer level can only determine whether the resistance of the line is larger or smaller (generally around 30-50Ω is used as the dividing point, and there are some differences between different multimeters).
Assume that the critical resistance value for the multimeter's buzzer to emit a buzzing sound is 50Ω. Then, when the resistance of the line or load is less than 50Ω, the buzzer will sound, and the smaller the resistance, the louder the buzzer. But when the line or load resistance is greater than 50Ω, the buzzer will not sound. Therefore, when the line resistance is greater than 50Ω or ∞, we cannot tell it using the buzzer mode.
Judging the quality of single-phase motors
A single-phase motor has two coil windings, one is the starting winding and the other is the running winding. Since the running winding coil is thicker and the starting winding coil is thinner, the resistance of the starting winding is larger than that of the running winding. The specific resistance value is related to the motor model and power. It can range from more than ten ohms to one or two hundred ohms. (The greater the power of the motor, the smaller the resistance; the smaller the power, the greater the resistance)
If the power of the motor is very small, its resistance will be very large. If the resistance is greater than 50Ω, the result when we use the buzzer setting is that it does not sound. Similarly, if the motor winding is burned out, it will not sound when we use the buzzer setting.
If the motor has a large power, its resistance will be very small. If the resistance is less than 50Ω, the result we measure with the buzzer setting is a buzzer. Similarly, if a short circuit occurs in the middle of the motor winding, the result we measure using the buzzer gear will also be a buzzer.
Therefore, in the situation you mentioned, there is really no way to judge whether the motor is good or bad. To judge the quality of the motor, it is necessary to analyze it based on the motor resistance and power.
For electrician friends who are new to multimeters, I suggest that when using a multimeter to measure lines or loads, try to use the resistance mode instead of the buzzer mode. This is very helpful for repairing and mastering the multimeter. Only after you are proficient in using a multimeter to measure resistance can you use the buzzer mode to speed up maintenance.
