VFD tripping frequently, what are the common causes?
My VFD has started tripping frequently, sometimes multiple times a day. It's not always the same fault code, but it's interrupting production. What are the most common reasons for a VFD to trip?
Frequent VFD trips indicate an underlying issue that needs diagnosis. While fault codes can vary, common causes often relate to power supply, motor issues, or environmental factors. Start by checking the VFD's fault log for recurring patterns and inspect the motor and cabling.
Likely causes and checks
1Overcurrent or Ground Fault
- Points to it
- These are very common trips. They often indicate a problem with the motor, motor cabling, or a mechanical issue causing the motor to draw excessive current. Signs include sudden stops, burning smell, or visible damage to cables.
- Check
- Isolate and lock out the VFD. Check motor winding resistance and insulation to ground. Inspect motor cables for damage, proper shielding, and correct termination. Verify the motor is not mechanically overloaded or jammed.
2DC Link Voltage Fluctuations (High/Low)
- Points to it
- Trips related to DC voltage suggest issues with the incoming power supply or the VFD's internal rectifier/capacitor bank. This can be caused by unstable grid voltage, sags, swells, or loose connections. You might notice other electrical equipment also behaving erratically.
- Check
- Check incoming line voltage stability at the VFD input terminals with a multimeter. Inspect input power connections for looseness or corrosion. If possible, monitor the DC link voltage in the VFD's diagnostic menu for fluctuations before a trip.
3Overload (Motor or Inverter)
- Points to it
- Overload trips indicate the motor is drawing more current than its rated capacity or the VFD's capacity for an extended period. This can be due to mechanical binding, incorrect VFD programming, or an undersized motor/VFD for the application. The motor or VFD might feel excessively hot.
- Check
- Verify the VFD's motor parameters match the motor nameplate data. Check the mechanical load on the motor for any binding, excessive friction, or blockages. Ensure the motor and VFD are correctly sized for the application.
4Over-temperature (Drive or Motor)
- Points to it
- Temperature-related trips mean the VFD's internal components or the motor are getting too hot. This can be caused by blocked cooling fins, failed cooling fans, high ambient temperature, or excessive load. The VFD or motor housing will be hot to the touch.
- Check
- Inspect VFD heatsinks and cooling fans for dust, debris, or obstruction. Verify the VFD's internal cooling fan is operating. Check the ambient temperature around the VFD and motor. Ensure the motor's cooling fins are clean and its fan is intact.
Next check: After addressing the most likely causes, if the VFD continues to trip, review the VFD's fault log for any recurring specific fault codes and consult the drive's manual for detailed troubleshooting steps for those codes. Consider contacting technical support if the issue persists.
What it typically looks like in the data
Related questions
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