In order to prevent lightning strike or the influence of high-order harmonic of power supply, the frequency converter will generally combine a small circuit board on the inlet ports R, s and t of the frequency converter. There are three varistors on the circuit board, which are connected in parallel to the three phases R, s and t for overvoltage protection. There are also three magnetic chip capacitors, one end of which is connected to R, s and t respectively, and the other end of the three capacitors is connected to the ground terminal of the frequency converter after forming a point. If the frequency converter is only powered on and does not operate, it is 220V voltage to the ground. There must be leakage in at least one of the three capacitors. You can find the manufacturer to replace it or cut off the capacitor directly. If there is no leakage when the power is on, the leakage will occur after the operation of the frequency converter. Generally, it is caused by the high-order harmonic generated by the frequency converter itself, which needs to be reliably grounded. However, at any time, the inverter must be grounded in case of personal safety accidents caused by electric leakage.
1、 Daily inspection of frequency converter
Once every two weeks, check and record the output three-phase voltage of the frequency converter in operation, and pay attention to comparing the balance between them; Check and record the three-phase output current of the frequency converter, and pay attention to comparing the balance between them; Check and record the ambient temperature and radiator temperature; Check whether the frequency converter has abnormal vibration, sound and whether the fan operates normally.
2、 Frequency converter maintenance: each frequency converter shall be cleaned and maintained once a quarter.
During maintenance, dust and dirt should be removed from the inside of the frequency converter and the air path, and the surface of the frequency converter should be wiped clean; The surface of the frequency converter should be kept clean and bright; At the same time of maintenance, carefully check the frequency converter to see whether there are heating and discoloration parts in the frequency converter, whether the cement resistance is cracked, whether the electrolytic capacitor has expansion and leakage, whether the explosion-proof hole is prominent, whether the PCB board is abnormal, and whether there are heating and yellow parts. After the maintenance, restore the parameters and wiring of the frequency converter, power on, and operate the motor at the low frequency of 3Hz for about 1 minute to ensure the normal operation of the frequency converter.