19 Inverter Fault Codes

The use of Inverters in modern industry has become very common. Although the use of Inverter is becoming safer, more efficient, and more energy-efficient, it is also inevitable that Inverter will malfunction during operation. When the Inverter malfunctions, the corresponding fault code usually appears. So what are the faults that occur in the Inverters when these fault codes appear? How should we handle it?

The following nineteen common fault codes and their handling methods are for reference only.

1. Inverter overcurrent fault

※ Fault code: OCF

(1) Fault name: Inverter overcurrent fault

(2) The cause of the malfunction: incorrect input of data on the motor nameplate: the load being dragged by the motor is too heavy: mechanical jamming. The motor is locked.

(3) Method to solve the problem: Check whether the motor nameplate data in the Set and Motor Control menus is correctly entered; Whether the overcurrent protection threshold is appropriate: check the selection of Inverter and whether it is suitable for the motor and load, and check whether the motor is blocked; Check if the machine is stuck.

2. Motor short circuit fault

※ Fault code: SCF

(1) Fault name: The Inverter can display SCF1 motor short circuit based on the degree of short circuit; SCF2 has impedance short circuit; SCF3 is short circuited to ground.

(2) Reason for failure: SCF1: When a short circuit occurs between the output phases of the Inverter or between the output and ground, hardware is used to detect the fault and respond quickly (several microseconds). The current threshold that triggers the fault is between 3-4 times the rated current of the Inverter.

(3) SCF2: Due to impedance short circuit between the output phases or the output phase to ground of the Inverter, software is used to detect this fault for a few milliseconds. Possible reasons for the grounding of the Inverter output include: short circuit of the motor itself; Long motor cables, if multiple motors are connected in parallel and the cable length between the motor and the Inverter exceeds 80 meters, without using a motor reactor or a sine wave filter on the output side of the Inverter to reduce ground leakage current.

(4) The cause of the fault: insulation problem of the cable from the motor or Inverter to the motor; Current transformer fault; Power board including | GBT power part failure; Control board malfunction. SCF3: When the motor starts or runs, it detects a short circuit between the output of the Inverter and the ground, and the Inverter detects a large leakage current between the output and the ground.

(5) Solution to the fault: Check the cable insulation between the Inverter and the motor; Check the insulation of the motor; If the cable between the motor and the Inverter is too long, a motor reactor or a sine wave filter on the output side of the Inverter should be used to reduce ground leakage current; Reduce the switching frequency of the Inverter and check if the GBT power section is normal.

3. Braking overspeed fault

※ Fault code: OBF

(1) Fault name: Braking overspeed.

(2) The cause of the fault: Due to excessive braking or large load inertia, the internal DC bus voltage of the Inverter suddenly increases.

(3) The method to solve the problem is to increase the deceleration time of the Inverter as much as possible; The deceleration time adaptation (brA) function can be activated without using a braking resistor; If necessary, additional braking resistors should be added and the resistance and power of the braking resistor should be correctly calculated according to actual requirements.

4. Inverter overheat fault

※ Fault code: OHF

(1) Fault Name: Inverter Overheating Fault

(2) Reason for malfunction: Check the motor load; Check if the cooling fan of the Inverter is malfunctioning. The reason is that the temperature of the power part of the Inverter is too high due to the heavy load of the motor or poor heat dissipation of the Inverter.

(3) Method to solve the problem: Check if the ventilation of the Inverter is good and if there is any dirt blocking. Check if the ambient temperature of the Inverter is too high. Take appropriate measures to reduce the ambient temperature to ensure the cleanliness of the operating environment of the Inverter. When the Inverter overheats, wait for the temperature of the Inverter to drop before starting the Inverter.

5. Motor overload fault

※ Fault code: OLF

(1) Fault name: Motor overload fault.

(2) The cause of the fault: Due to excessive current in the motor, the thermal protection of the motor inside the Inverter was triggered.

(3) Solution to the fault: Check the load condition of the motor; Check the motor thermal protection parameter settings of the Inverter; Wait for the motor to cool down before starting it.

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6. Motor phase failure

※ Fault code: OPF

(1) Fault name: Motor phase loss fault.

(2) Reason for the malfunction: The Inverter is not connected to the motor; The motor power does not match the Inverter power, and the motor is too small; The motor runs at no load, and the running current of the motor is unstable and discontinuous, resulting in the Inverter not being able to detect the motor current.

(3) Solution to the fault: Check the connection between the Inverter and the motor; If conducting small motor testing, the motor phase loss protection function of the Inverter should be turned off, and the output phase loss setting (○ PL)=not set (nO); Check if the motor rated voltage (UnS), motor rated current (ncr), and IR stator voltage drop compensation (UF) parameters are set correctly, and perform self tuning (tUn) operation.

7. Input overvoltage fault

※ Fault code: OSF.

(1) Fault name: Inverter input overvoltage fault.

(2) The cause of the fault: The input main power supply voltage of the Inverter is too high, and the instantaneous fluctuation of the main power supply voltage is too large.

(3) Solution to the fault: Check the main power supply voltage, and the voltage fluctuation range should not exceed the allowable range of the Inverter.

8.Communication failure of Inverter 

※ Fault code: SLF.

(1) Fault name: Communication failure of Inverter.

(2) The cause of the malfunction is a communication interruption on the Inverter communication bus.

(3) Solution to the problem: Check if the communication connection is normal; Check communication timeout settings; Check the communication program.

9. Inverter undervoltage fault

※ Fault code: USF.

(1) Fault name: Inverter undervoltage fault.

(2) Reason for malfunction: The input main power supply voltage of the Inverter is too low. The instantaneous fluctuation of the main power supply voltage is too large.

(3) Solution to the fault: Check the main power supply voltage, and the voltage fluctuation range should not exceed the allowable range of the Inverter; Check if the Under Voltage Management (USb) parameter settings are appropriate.

10. Inverter input phase failure

※ Fault code: PHF

(1) Fault name: Inverter input phase loss fault.

(2) The cause of the fault: the inverter power supply is out of phase or incorrect; The Inverter is powered by a DC bus

(3) Solution to the fault: Check the power supply connection of the Inverter; Check the power supply voltage and phase sequence of the Inverter; Check if the incoming fuse is blown; If the Inverter uses DC bus power supply, input phase loss (IPL)=N ○ should be set to shield the input phase loss protection.

11. Short circuit fault of Inverter braking unit

※ Fault code: BUF

(1) Fault name: Short circuit fault of braking unit.

(2) The cause of the fault: the braking resistor of the Inverter is burnt out, causing a short circuit in the braking unit; Short circuit of braking unit output; The brake unit is not connected to certain models of Inverter.

12. Fault in the pre charging circuit of the Inverter

※ Fault code: CrF

(1) Fault name: Inverter pre charging circuit fault.

(2) The cause of the fault: The relay or pre charging resistor in the internal charging circuit of the Inverter is damaged.

(3) The method to solve the problem: The Inverter should be powered off first and then powered on later. If the problem cannot be eliminated, the Inverter must be repaired.

13. Motor overspeed fault

※ Fault code: SOF

(1) Fault name: Motor overspeed fault

(2) The cause of the malfunction is unstable operation of the motor; The inertia of the load dragged by the electric motor is too large.

(3) Method to solve the problem: Check the parameter settings related to the motor nameplate data, inverter gain, and stability in the Inverter parameters; If necessary, the braking resistance can be increased.

14. Motor self-tuning fault

※ Fault code: TNF

(1) Fault name: Motor self tuning fault.

(2) The cause of the malfunction: Due to the use of a special motor or the power of the motor not matching the Inverter, or the motor not being connected properly, the Inverter failed to complete its self tuning during the motor self tuning.

(3) Solution to the fault: Check the connection between the Inverter and the motor; Check and confirm that the Inverter and motor are compatible with each other.

15. Speed feedback loss fault

※ Fault code: SPF

(1) Fault name: Speed feedback loss fault.

(2) Reason for the malfunction: During the operation of the Inverter, the encoder feedback signal was lost.

(3) Solution to the fault: Check the connection between the Inverter and the encoder; Check the encoder.

16. Encoder malfunction

※ Fault code: EnF

(1) Fault name: Encoder fault.

(2) The cause of the malfunction: The encoder has malfunctioned.

(3) Solution to the fault: Check the parameter settings of the number of pulses (PG |) and encoder type (EnS) related to the encoder in the Inverter; Check the mechanical and electrical connections of the encoder.

17. The Chinese panel of the Inverter cannot be connected or the screen is black

(1) The cause of the fault: there is a fault in the Chinese panel of the Inverter, the internal power supply of the Inverter is faulty, and the Chinese panel of the Inverter is not connected properly.

(2) Method to solve the problem: Check the connection between the panel and the Inverter, and check the 24 V power supply of the Inverter; Replace the Chinese panel.

18. Inverter display nLP

※ Display code: nLP

(1) Code name: The Inverter has no main power supply.

(2) The cause of the malfunction: The Inverter only has control power supply, and the main power supply is not supplied or the fuse on the input side of the Inverter is blown.

(3) Solution to the fault: Check the incoming power supply of the Inverter; Check the fuse, the power of the Inverter is relatively low, check the connection of the short connectors of PO and PA+, and whether the bolts are tightened. If DC reactance is used, ensure that the DC reactance is connected to PO and PA+.

19. Inverter display PrA

※ Display code: PrA.

(1) Code name: The power off function of the Inverter is effective, and the Inverter is locked.

(2) The reason for the malfunction: Some Inverter have added safety application functions, and the PWR control terminal of the Inverter is not powered on.

(3) Solution to the fault: Check the PWR control terminal of the Inverter.

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