TOP 10 common faults and troubleshooting methods of VFD

When frequency inverter faults, there often have obvious abnormal manifestations, which may be shown in the following aspects:

1. Alarm code display: most frequency converters are equipped with display screens, and specific codes will shown when there is a fault;
2. Abnormal sound or vibration: sharp noise or severe vibration is emitted during operation, the noise level should below 65 decibels during normal operation; 
3. Overheating or smoking: If the cooling fan stops running or blocked, the temperature will exceed 85 ℃, which will trigger overheating protection.

When the above obvious abnormalities occur, we need to check the role and operating conditions of the frequency converter in the equipment:

1. If this is a newly installed VFD, We need to determine whether the parameters have been fully adjusted;
2. If the VFD used for some time, it is necessary to check the operating conditions mentioned, such as whether the start signal is properly connected to the frequency converter and whether the signal conditions of the control circuit are all right;
3. Whether the input voltage is within the rated requirement range, and whether the output voltage and current are within the rated range, etc;
4. Learn under the circumstances when the fault shutdown occurs;
5. Alarm codes for VFD;
6. Check if the wiring of the frequency converter is secure, free from looseness or poor contact.

TETRANCA summarize the TOP 10 reasons and solutions for the most frequent VFD faults:

1. Accelerate overcurrent

Possible causes of the malfunction include:

1. The output circuit of the frequency converter is grounded or short circuited
2. The control method is vector and no parameter identification has been performed
3. The acceleration time is too short
4. Manual torque increase or inappropriate V/F curve
5. Low voltage
6. Start the rotating motor
7. Sudden increase in load during acceleration process
8. The selection of VFD power is too small

The countermeasures:

1. Eliminate peripheral faults
2. Identify motor parameters
3. Increase acceleration time
4. Adjust manual torque or V/F curve
5. Adjust the voltage to the normal range
6. Choose to start with speed tracking or wait for the machine to stop before starting again
7. Cancel sudden load
8. Choose a VFD with a higher power level

2. Deceleration overcurrent

Possible causes of the malfunction include:

1. The output circuit of the frequency converter is grounded or short circuited
2. The control method is vector and no parameter identification
3. The deceleration time is too short
4. Low voltage
5. Sudden increase in load during deceleration process
6. No brake unit or brake resistor installed

The countermeasures:

1. Eliminate peripheral faults
2. Perform motor parameter identification
3. Increase deceleration time
4. Adjust the voltage to the normal range
5. Cancel sudden load
6. Install brake unit and resistor

3. Constant speed overcurrent

Possible causes of the malfunction include:

1. The output circuit of the frequency converter is grounded or short circuited
2. The control method is vector and no parameter identification
3. Low voltage
4. Is there a sudden increase in load during operation
5. The selection of frequency converter is too small

The countermeasures for troubleshooting include:

1. Eliminate peripheral faults
2. Motor parameter identification
3. Adjust the voltage to the normal range
4. Cancel sudden load
5. Choose a VFD with a higher power level

4. Accelerated overvoltage

Possible causes of the malfunction include:

1. Input voltage is too high
2. During the acceleration process, there is an external force dragging the motor
3. The acceleration time is too short
4. No install brake unit or brake resistor

The countermeasures:

1. Adjust the voltage to the normal range
2. Cancel additional power or install braking resistors
3. Increase acceleration time
4. Install brake unit and resistor

5. Deceleration overvoltage

Possible causes of the malfunction include:

1. Input voltage is too high
2. During the deceleration process, there is an external force dragging the motor to operate
3. The deceleration time is too short
4. Equipped with brake unit and brake resistor

The countermeasures for troubleshooting include:

1. Adjust the voltage to the normal range
2. Cancel additional power or install braking resistors
3. Increase deceleration time
4. Install brake unit and resistor

6. Constant speed overvoltage

Possible causes of the malfunction include:

1. Input voltage is too high
2. There is external force dragging the motor during operation

The countermeasures for troubleshooting include:

1. Adjust the voltage to the normal range
2. Cancel additional power or install braking resistors

7. Undervoltage fault

Possible causes of the malfunction include:

1. Instantaneous power outage
2. The input voltage of the frequency converter is not within the range required by the specifications
3. Abnormal bus voltage
4. The rectifier bridge and buffer resistor are abnormal
5. Driver board abnormality
6. Abnormal control board

The countermeasures for troubleshooting include:

1. Reset fault
2. Adjust the voltage to the normal range
3. Seeking technical support from manufacturers

8. Overload of frequency converter

Possible causes of the malfunction include:

1. Is the load too large or is there motor stalling
2. The selection of frequency converter power is too small

The countermeasures for troubleshooting include:

1. Reduce the load and check the motor and mechanical condition
2. Choose a frequency converter with a higher power level

9. Output missing items

Possible causes of the malfunction include:

1. The lead from the frequency converter to the motor is abnormal
2. The three-phase output of the frequency converter is unbalanced during the operation of the motor
3. Driver board abnormality
4. Module abnormality

The countermeasures for troubleshooting include:

1. Eliminate peripheral faults
2. Check if the three-phase winding of the motor is normal and eliminate the fault
3. Seeking technical support from manufacturers

10. Module overheating

Possible causes of the malfunction include:

1. The ambient temperature is too high
2. Air duct blockage
3. Fan damaged
4. Module thermistor damaged
5. Inverter module damaged

The countermeasures for troubleshooting include:

1. Reduce the ambient temperature
2. Clean the air duct
3. Replace the fan
4. Replace thermistor
5. Replace the inverter module

How to avoid frequency converter faults, TETRANCA Electric engineers give you some suggestions!

1. Regular cleaning: Based on the on-site environmental conditions, we recommended to regularly clean the interior of the VFD, cooling fans and air ducts, to avoid dust accumulation that can cause poor heat dissipation and damage to components.
2. Parameter backup: Save the parameter settings for normal operation, which can be quickly restored after fault recovery.
3. Replacement of vulnerable parts: The lifespan of electrolytic capacitors is about 5 years