How to measure how many volts in and out with a multimeter
Use a multimeter to measure the DC voltage at both ends of P and N. Normally, it is around 310V, and the output AC voltage (U, V, W) is generally not higher than 200V. If there is no 310V DC voltage at the input of the power module, it means that There is a problem with the rectifier and filter circuit of the machine, but it has nothing to do with the power module; if there is a 310V DC input, but no AC output lower than 200V, or the output voltages between the U, V, and W three phases are uneven, it can be judged that the power module has fault and replace. 2. Use the red test lead of the multimeter to connect to the P terminal and the black test lead to the U, V, and W terminals when the machine is not connected. The forward resistance should be the same. If the resistance value of any one of them is not equal to the other two, it can be judged that the power module is damaged; use the black test lead to the N terminal and the red test lead to the U, V, and W terminals respectively, and the resistance values of each item should also be equal, such as It can also be judged that the power module is damaged and should be replaced. 3. Use a multimeter to measure the forward resistance of the P terminal to the U, V, and W terminals, which should be about 500 ohms, and the reverse direction is infinite. Use a multimeter to measure the forward resistance of the N terminal to the U, V, and W terminals. It should be about 500 ohms , the reverse is infinite, otherwise the power module is judged to be damaged and should be replaced. 4. When judging the quality of the power module, the compressor and drive power supply should also be checked
