AI Over Frequency

What does F25 mean?

This fault indicates an over-frequency condition detected by the anti-islanding protection. This mechanism ensures the inverter disconnects from the grid if grid power is unstable or absent, preventing dangerous backfeeding and potential damage to equipment.

• Grid supply frequency exceeding the inverter's configured upper threshold (e.g., 50.5 Hz or 60.5 Hz) for the anti-islanding protection.
• Transient frequency spike on the grid due to nearby generator synchronization, sudden load shedding, or instability within the utility network.
• Inverter's internal frequency measurement circuit experiencing drift or failure, leading to an erroneous over-frequency detection.
• Anti-islanding parameter P_AI_Freq_High set too close to the nominal grid frequency, making the system overly sensitive.

Click steps to track your progress.

1. 1

   Using a true RMS multimeter with frequency measurement, monitor the incoming grid frequency at the inverter's AC input terminals (e.g., L1-L2) over a 15-minute period.

2. 2

   Compare the recorded frequency against the inverter's configured anti-islanding high-frequency trip point (e.g., Parameter P_AI_Freq_Max).

3. 3

   Inspect the integrity of the AC voltage sensing connections on the inverter's input terminals for any signs of corrosion or looseness.

4. 4

   If measured grid frequency is stable and within limits, consider increasing the anti-islanding over-frequency threshold (e.g., Parameter P_AI_Freq_Max by 0.2 Hz) only if compliant with local grid codes.

5. 5

   If the fault persists despite stable grid and parameter adjustments, initiate an inverter self-diagnostic routine to assess the internal frequency measurement hardware.