When the frequency converter breaks down, it is necessary to deal with the fault of the frequency converter in a timely and effective manner. Generally, the fault of the frequency converter will report the corresponding fault code. You can quickly judge the fault of the frequency converter by comparing the fault code table. Today, let's learn the common fault codes and fault handling methods of the frequency converter.

1. Fault code: OCF (frequency converter overcurrent fault)

Cause of failure: incorrect input of motor nameplate data: the load driven by the motor is too heavy: the machine is stuck; The motor is locked.

Troubleshooting: check whether the motor nameplate data in the set and DRC menus is correctly input; Whether the overcurrent protection threshold is appropriate: check whether the selection of frequency converter is appropriate to the motor and load, and whether the motor is locked; Check whether the machine is stuck.

2. Fault code: SCF (motor short circuit fault)

The frequency converter can display the short circuit of scf1 motor according to the different degree of short circuit; Scf2 has impedance short circuit; ScF3 is short circuited to ground.

Cause of fault: insulation problem of cable from motor or frequency converter to motor; Current transformer fault; The power board includes | GBT power part failure; The control board is faulty.

Scf1: when there is a short circuit between inverter output phases or output to ground, use hardware to detect the fault and respond quickly (a few microseconds), and the current threshold triggering the fault is between 3~4 times the rated current of the inverter.

Scf2: the inverter has an impedance short circuit due to the inverter output phase to phase or the output phase to ground. Use software to detect this fault for several milliseconds. The possible reasons for the inverter output grounding are: the short circuit of the motor itself; For long motor cables, if there are multiple motors in parallel, the length of the cable between the motor and the frequency converter is more than 80 meters, without using the motor reactor or the sine wave filter on the output side of the frequency converter to reduce the ground leakage current.

ScF3: when the motor starts or runs, it is detected that there is a short circuit between the output of the frequency converter and the ground, and the frequency converter detects that there is a large leakage current between the output and the ground.

Troubleshooting: check the cable insulation between the frequency converter and the motor; Check the motor insulation; If the cable between the motor and the frequency converter is too long, the motor reactor or the sine wave filter on the output side of the frequency converter should be used to reduce the ground leakage current; Reduce the switching frequency of the frequency converter and check whether the GBT power part is normal.

3. Fault code: oBf (braking overspeed fault)

Cause of fault: the voltage of DC bus inside the frequency converter rises suddenly due to excessive braking or too large load inertia.

Solution: increase the deceleration time of the frequency converter as much as possible; When the braking resistor is not used, the deceleration time adaptation (BRA) function can be activated; If necessary, the braking resistor shall be added, and the resistance value and power of the braking resistor shall be calculated correctly according to the actual requirements.

4. Fault code: OHF (frequency converter overheat fault)

Cause of fault: check the motor load; Check whether the cooling fan of the frequency converter is faulty: the temperature of the power part of the frequency converter is too high due to the heavy load of the motor or the poor cooling of the frequency converter.

Troubleshooting: check whether the inverter is well ventilated and blocked by dirt. Check whether the ambient temperature of the inverter is too high. Take appropriate measures to reduce the ambient temperature and ensure the cleanness of the inverter operating environment. When the inverter overheats, wait for the temperature of the inverter to drop before starting the inverter.

5. Fault code: OLF (motor overload fault)

Cause of fault: the motor thermal protection inside the frequency converter is triggered due to excessive current in the motor.

Solution: check the load of the motor; Check the motor thermal protection parameter setting of the frequency converter; Wait for the motor to cool before starting it.

6. Fault code: OPF (motor phase failure)

Cause of failure: the frequency converter is not connected to the motor; The motor power does not match the inverter power, and the motor is too small; When the motor runs at no-load, the running current of the motor is unstable and discontinuous, resulting in the failure of the frequency converter to detect the motor current.

Solution: check the connection between frequency converter and motor; If the small motor test is carried out, the motor phase loss protection function of the frequency converter should be turned off, and the output phase loss setting (○ PL) = not set (no); Check whether the motor rated voltage (UNS), motor rated current (NCR) and IR stator voltage drop compensation (UF) parameter settings are correct, and carry out self-tuning (Tun) operation.

7. Fault code: OSF (input overvoltage fault)

Cause of failure: the input main power supply voltage of the frequency converter is too high, and the instantaneous fluctuation of the main power supply voltage is too large.

Solution: check the main power supply voltage, and the voltage fluctuation range should not exceed the allowable range of the frequency converter.

8. Fault code: SLF (frequency converter communication failure)

Cause of failure: communication interruption on the communication bus of frequency converter.

Solution: check whether the communication connection is normal; Check the communication timeout setting; Check the communication procedure.

9. Fault code: USF (inverter undervoltage fault)

Cause of failure: the input main power supply voltage of the frequency converter is too low, and the instantaneous fluctuation of the main power supply voltage is too large.

Troubleshooting: check the main power supply voltage, and the voltage fluctuation range should not exceed the allowable range of the frequency converter; Check whether the undervoltage Management (USB) parameters are set properly.

10. Fault code: PHF (inverter input phase failure)

Cause of failure: the power supply of the frequency converter is out of phase or incorrect; The frequency converter adopts DC bus for power supply

Solution: check the power supply connection of the frequency converter; Check the power supply voltage and phase sequence of the frequency converter; Check whether the incoming fuse is blown; If the frequency converter adopts DC bus power supply, input phase loss (IPL) =n ○ should be set to shield input phase loss protection.