E.OV2 Fault in Mitsubishi FR-E700 Drive

E.OV2 Regenerative Overvoltage Trip During Constant Speed in the Mitsubishi FR-E700 Drive indicates that the DC bus voltage has exceeded the allowable limit while the motor is operating at constant speed. During operation, the motor may generate regenerative energy due to sudden load changes or overhauling loads. If the regenerated energy cannot be absorbed or dissipated, the DC bus voltage rises above the protection threshold, causing the drive to generate Fault E.OV2 and stop the motor to protect the inverter power electronics.

E.OV2 Fault in Mitsubishi FR-E700 Drive


This fault generally indicates a problem with the load conditions, regenerative energy handling, braking configuration, or stall prevention settings, rather than a hardware failure of the drive.

Possible Causes

  • Sudden reduction in motor load.
  • Sudden load change during constant speed operation.
  • Overhauling or regenerative load.
  • Excessive regenerative energy.
  • Parameter 22 – Stall Prevention Operation Level set too low.
  • Regeneration avoidance function not enabled.
  • Incorrect settings for Parameters 882–886 (Regeneration Avoidance Function).
  • Brake resistor not installed where required.
  • Brake resistor disconnected or defective.
  • Brake unit malfunction.
  • Incoming supply voltage too high.
  • High-inertia load producing excessive regenerative energy.
  • Incorrect drive sizing for the application.
  • Internal brake circuit fault.

Solutions

  • Keep the mechanical load as stable as possible.
  • Check for sudden load changes during operation.
  • Verify that Parameter 22 – Stall Prevention Operation Level is correctly set.
  • Enable and configure the Regeneration Avoidance Function (Parameters 882–886) if applicable.
  • Install a brake resistor if the application requires regenerative braking.
  • Verify the brake resistor is correctly connected and in good condition.
  • Check the brake unit for proper operation.
  • Verify the incoming supply voltage is within Mitsubishi specifications.
  • Reduce regenerative energy by modifying the application if possible.
  • Confirm the drive is correctly sized for the load.
  • Inspect braking components for damage.
  • Restart the drive after correcting the cause.
  • Contact Mitsubishi technical support if the fault persists.

Additional Information

The Mitsubishi FR-E700 continuously monitors the DC bus voltage to protect the inverter from excessive voltage caused by regenerative energy.

During constant-speed operation, sudden load reductions or overhauling loads can cause the motor to operate as a generator. The regenerated energy flows back into the DC bus, increasing its voltage.

If the drive cannot absorb or dissipate this energy, it generates Fault E.OV2.

Mitsubishi recommends checking:

  • Sudden load changes.
  • Parameter 22 – Stall Prevention Operation Level.
  • Parameters 882–886 – Regeneration Avoidance Function.
  • Brake resistor or brake unit installation where required.

Unlike E.OV1, which occurs primarily during deceleration, E.OV2 occurs while the motor is operating at constant speed, typically due to changing load conditions.

Common Symptoms

  • Drive trips with E.OV2.
  • Fault occurs while the motor is running at constant speed.
  • Sudden load reduction before the fault.
  • High DC bus voltage.
  • Drive stops unexpectedly.
  • Fault occurs with overhauling loads.
  • Frequent trips during regenerative operation.
  • Fault clears after reset but returns under similar conditions.
  • Production process is interrupted.
  • Brake resistor may become excessively hot if undersized.

Recommended Troubleshooting Sequence

  1. Check for sudden load changes.
  2. Keep the mechanical load as stable as possible.
  3. Verify Parameter 22 – Stall Prevention Operation Level.
  4. Check Parameters 882–886 – Regeneration Avoidance Function.
  5. Enable regeneration avoidance if appropriate.
  6. Inspect the brake resistor.
  7. Verify brake resistor wiring.
  8. Check brake unit operation.
  9. Measure the incoming supply voltage.
  10. Review application load characteristics.
  11. Confirm correct drive sizing.
  12. Restart the drive.
  13. Test operation under normal load conditions.
  14. Monitor the DC bus voltage.
  15. Contact Mitsubishi technical support if the fault persists.

Regenerative Overvoltage Check Table

Check PointAction
Load stabilityEliminate sudden load changes
Parameter 22Verify Stall Prevention Operation Level
Parameters 882–886Configure Regeneration Avoidance Function
Brake resistorVerify installation and condition
Brake resistor wiringInspect connections
Brake unitCheck proper operation
Supply voltageVerify within specification
Regenerative loadEvaluate application conditions
Drive sizingConfirm suitability for the application
DC bus voltageMonitor during operation
Mitsubishi technical supportContact if the fault remains after inspection

Preventive Maintenance Tips

  • Maintain stable mechanical loading during constant-speed operation.
  • Configure Parameter 22 – Stall Prevention Operation Level according to the application.
  • Enable the Regeneration Avoidance Function (Parameters 882–886) for applications with regenerative loads.
  • Install a correctly rated brake resistor or brake unit when required.
  • Periodically inspect braking components and wiring.
  • Verify the incoming supply voltage remains within Mitsubishi specifications.
  • Monitor DC bus voltage during operation using drive diagnostics.
  • Ensure the drive is correctly sized for high-inertia or regenerative applications.
  • Replace damaged braking components promptly.
  • Record recurring regenerative overvoltage trips to assist long-term diagnostics.

Proper adjustment of Parameter 22 – Stall Prevention Operation Level, correct configuration of the Regeneration Avoidance Function (Parameters 882–886), maintaining a stable mechanical load, and using a properly rated brake resistor or brake unit where required will help prevent recurring E.OV2 Regenerative Overvoltage Trip During Constant Speed faults in Mitsubishi FR-E700 drives, ensuring reliable control of regenerative energy, stable DC bus voltage, and dependable long-term operation of the drive system.

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