Overfrequency

What does OF mean?

This fault indicates that the frequency of the incoming mains power supply has risen above the specified operating range. By default, this critical condition triggers a full TRIP, inhibiting all ignition pulses and resetting the Ready signal to prevent damage to the drive and motor that could result from operation at an incorrect frequency. Manual reset is required after the frequency stabilizes.

• Unstable or unregulated power source (e.g., poorly governed generator, microgrid anomaly) supplying the facility.
• Incorrectly set maximum frequency trip threshold parameter (e.g., P0-10) in the drive, causing premature tripping.
• Issues with the drive's internal mains frequency measurement circuit (uncommon, typically indicates hardware issue).
• Sudden shedding of large loads from a local generation source, leading to a temporary frequency overshoot.
• Resonance conditions in the power system causing frequency amplification.

Click steps to track your progress.

1. 1

   Measure the actual incoming mains frequency at the drive's input terminals (L1, L2, L3) using a true RMS multimeter or power analyzer; compare to expected 50 Hz or 60 Hz.

2. 2

   Check the drive's overfrequency trip threshold parameter (e.g., P0-10) and adjust if it is set too low (e.g., typically 53 Hz for 50 Hz system).

3. 3

   Monitor the utility grid's frequency stability over time using a data logger if the issue is intermittent.

4. 4

   Inspect the local generator's speed governor and frequency control system for proper operation and calibration.

5. 5

   Verify that there are no abnormal load shedding events on the same power bus that could cause frequency surges.