Cause : Overvoltage comes when the input power supply voltage to the drive has exceeded the permissible limit. This protective function safeguards the drive from potential damage.

"0u" fault in Fuji FRENIC-VG drive indicate "Overvoltage" condition. This means the DC bus voltage inside the drive has exceeded the permissible limit. This can occur when the incoming supply voltage is too high, when there is excessive regenerative energy from the motor (such as during deceleration), or due to a malfunction in the drive’s power circuitry.

Troubleshooting Steps:

1. Check Input Voltage:

   • Measure the AC input voltage to the drive and ensure it is within the specified range. If the voltage is too high, corrective actions, such as voltage regulation or adjustment of the power supply, may be needed.

2. Review Deceleration Parameters:

   • Check the drive’s deceleration time settings. If the deceleration time is too short, try increasing it to allow the motor to slow down more gradually, reducing the amount of regenerative energy returned to the drive.

3. Inspect the Braking System:

   • If the drive is equipped with a braking resistor or regenerative braking system, check that it is functioning correctly. Verify the connections and test the resistor for proper operation.
   • If the braking resistor is damaged or not functioning, replace it to ensure proper dissipation of regenerative energy.

4. Monitor Power Supply Stability:

   • Observe the stability of the power supply and look for any signs of surges or spikes that could be causing the overvoltage fault.
   • Consider using surge protection devices or a more stable power source if power fluctuations are identified.

5. Test the Drive:

   • If external factors appear to be in order, the issue may lie within the drive itself. Perform a diagnostic test on the drive’s power components and voltage detection circuits to identify any internal faults.
   • If a hardware issue is detected, the drive may require repair or replacement.