Variable Frequency Drive Troubleshooting Guide

 Variable Frequency Drives (VFDs) are essential in modern industrial environments for controlling motor speed, reducing energy consumption, and improving process performance. However, they can suffer from faults that impact productivity. In this guide, we’ll walk you through variable frequency drive troubleshooting methods to fix the most common issues faced by engineers and technicians in the field. Regular VFD maintenance is also essential to prevent many of these faults before they happen.

Variable Frequency Drive Troubleshooting

Below are five of the most common VFD faults and how to diagnose and resolve them:

1. Overvoltage Fault (EOV / E203)

This occurs when the DC bus voltage exceeds the safe threshold. It usually happens during rapid deceleration or if there's regenerative energy from the motor.

• Causes: Poor braking resistor sizing, fast deceleration, or input voltage spikes.

• Fix: Adjust deceleration time, install a braking resistor, and stabilize the power supply.

Need a downloadable checklist for common VFD drives troubleshooting issues? Access the full guide here 

2. Overcurrent Fault (OCF / F012)

An overcurrent fault means the drive is drawing too much current—usually during startup or sudden load changes.

• Causes: Short circuits, mechanical jamming, or incorrect motor parameters.

• Fix: Inspect motor connections, remove blockages, and verify motor settings in the drive.

3. Motor Overload (OL / F013)

This fault appears when the motor runs at a current above its rated limit for too long.

• Causes: Overloaded machinery, blocked ventilation, or an undersized motor.

• Fix: Reduce the load, improve cooling, or resize the motor.

4. Under voltage Fault (UV / E012)

The VFD will trigger this fault if the supply voltage drops below the acceptable range.

• Causes: Weak power source, unstable grid, or loose wiring.

• Fix: Check and tighten terminals, test input voltage, and consider installing a voltage regulator.

5. Ground Fault (GF / F005)

This indicates leakage current between the motor and ground, which can be dangerous if left untreated.

• Causes: Damaged cable insulation, moisture inside the motor, or worn motor windings.

• Fix: Use a megger to check insulation, dry the motor, and replace faulty cables.

Read More: Essential Guide to Industrial Drives Maintenance for Optimal Efficiency

Conclusion

Mastering variable frequency drive troubleshooting can save time, prevent costly downtime, and extend the life of your equipment. Whether you're dealing with basic error codes or complex electrical issues, having a solid VFD drives troubleshooting strategy is essential.