What is the difference between the resistance range and the buzzer range of a multimeter when measuring continuity?
Many friends like to use the beep mode to judge the continuity of the circuit or the quality of the equipment, and there are also many friends who like to use the resistance mode to judge the continuity of the circuit or the quality of the equipment. That's the question, what is the difference between the multimeter resistance mode and the buzzer mode when measuring on/off?
The difference between them is:
The resistance range of a multimeter can measure the specific resistance of a circuit, and then we can analyze and determine whether the circuit is normal or if there are any faults based on the resistance value.
The buzzing mode can only determine whether the resistance of the circuit is high or low (usually around 30-50 Ω as the dividing point, with some differences depending on the multimeter).
Assuming the critical resistance value for the multimeter to emit a beep sound is 50 Ω, the beep sound will only occur when the resistance of the circuit or load is less than 50 Ω, and the smaller the resistance, the greater the beep sound. But when the resistance of the circuit or load is greater than 50 Ω, the buzzing mode will not sound. So when the resistance of the circuit is greater than 50 Ω or ∞, we cannot distinguish it using the buzzer mode
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A single-phase motor has two coil windings, one is the starting winding and the other is the running winding. Due to the thicker running winding coil and thinner starting winding coil, the resistance value of the starting winding is higher than that of the running winding. The specific resistance value depends on the motor model and power, ranging from tens of ohms to one or two hundred ohms. (The greater the motor power, the smaller the resistance; the smaller the power, the larger the resistance)
If the power of the motor is very low, its resistance value will be very high. If the resistance value is greater than 50 Ω, the result we measured using the buzzer mode will not sound. Similarly, if the motor winding burns out, we will not make any sound even when using the buzzer mode for testing.
If the motor has a high power, its resistance will be very small. If the resistance is less than 50 Ω, the result we measured using the buzzer mode is that there is a buzzing sound. Similarly, if a short circuit occurs in the middle of the motor winding, the result we measured using the buzzer mode will also produce a buzzing sound.
