How to use a multimeter to test the quality of a motor simply and quickly
How to use a multimeter to test the quality of a motor simply and quickly
Set the pointer multimeter to the 1Ω position (zero calibration) or the digital multimeter to the 200Ω electrical barrier. For three-phase asynchronous motors, it is mainly to measure Y/△ (U1, U2, Ⅴ1, Ⅴ2, W1, W2) resistance value between them.
A terminal box for a three-phase asynchronous AC motor with standard delta connection. Because they are connected head to tail, the rated voltage between each phase is the line voltage (commonly 380V). Then, use a pointer multimeter to measure the resistance values between U1 and V1, U1 and W1, V1 and U1, V1 and W1, W1 and U1, and W1 and V1, respectively. The resistance values should be basically the same. The value of this resistance depends on the rated power of the three-phase AC asynchronous motor. The greater the rated power, the smaller the resistance value of the motor. Anyway, it cannot be equal to zero (equal to zero, indicating that there is a short circuit or burnout inside the motor coil), and the resistance value of the two endpoints cannot be infinite ∞ (∞ is infinite, indicating that the internal coil winding of the motor is burned out or disconnected).
How to measure voltage range with digital multimeter
1. Measurement of DC voltage, such as batteries, walkman power supplies, etc. First, insert the black test lead into the "com" hole and the red test lead into the "V Ω" hole. Select the knob to a range larger than the estimated value (note: the values on the dial are the maximum range, "V-" represents the DC voltage range, "V~" represents the AC voltage range, and "A" represents the current range), and then Connect the test leads to both ends of the power supply or battery; keep the contact stable. The value can be read directly from the display. If it is displayed as "1.", it means that the range is too small, so it is necessary to increase the range before measuring industrial electrical appliances. If "-" appears on the left side of the value, it means that the polarity of the test lead is opposite to the actual power supply polarity. At this time, the red test lead is connected to the negative pole.
2. Measurement of AC voltage. The test lead jack is the same as the DC voltage measurement, but the knob should be turned to the required range at the AC gear "V~". There is no positive or negative distinction between AC voltage, and the measurement method is the same as before. Regardless of whether you are measuring AC or DC voltage, you must pay attention to personal safety and do not touch the metal parts of the test leads with your hands.
