Damage to the rectifier of the variable frequency drive is generally due to the grid voltage or an internal short circuit. Exclude internal short circuit case, the replacement of the bridge rectifier. At the scene to deal with failure, should focus on examination of the grid situation, such as the grid voltage, with or without welding machines and other contaminated equipment on the grid and so on. Damage to the VFD drive module is generally caused by the motor or cable is damaged and the drive circuit failure.

In the repair of the drive circuit, the measured drive waveform in good condition, replace the module. Drive's board is replaced, it must also pay attention to check the motor and connection cable. Determine without any fault, run the variable frequency drive. Power-on in general may also be damaged due to the switching power supply is damaged or soft charge circuit to the DC circuit caused by direct current, such as the startup resistor is damaged, the panel damage.

Displayed after the power voltage or under voltage, generally due to the input shortage relative to aging, the circuit board caused by damp, to find out the voltage detection circuit and the detection point, replacement of damaged devices. Displayed after power-on current or shorted to ground is due to the current sensing circuit is damaged, such as the Hall element, the op amp. The start display the current drive circuit or frequency drive module damage caused. No-load output voltage is normal, overload or overcurrent load, the situation is generally due to the aging of the parameter is set incorrectly or drive circuit module damage caused.