AI Under Frequency

What does F24 mean?

This fault indicates an under-frequency condition detected by the anti-islanding protection, exceeding the AC qualification limits. 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 frequency dropping below the inverter's anti-islanding protection threshold (e.g., below 49.5 Hz for a 50 Hz system).
• Sudden large load increase on the local grid segment, causing the grid frequency to sag temporarily.
• Malfunction of the grid frequency measurement circuit within the inverter, providing erroneous low readings.
• Configuration error in the anti-islanding parameters, setting the under-frequency trip point too high (e.g., Parameter G1-03 set to 49.8 Hz).
• Weak or unstable grid connection, making the inverter more susceptible to minor frequency fluctuations.

Click steps to track your progress.

1. 1

   1. Measure the actual grid frequency at the inverter's AC input terminals (e.g., using a power quality analyzer like a Fluke 435 Series II) and compare it to the inverter's displayed frequency.

2. 2

   2. Verify the anti-islanding under-frequency trip setting in the inverter's parameters (e.g., Parameter G1-03) and ensure it matches local grid codes.

3. 3

   3. Check for any recent large load changes or disturbances on the local electrical grid that could explain a frequency sag.

4. 4

   4. Power cycle the inverter to reset its internal frequency measurement circuits and clear any transient conditions.

5. 5

   5. Inspect the AC input connections for looseness or corrosion that could affect voltage and frequency measurement stability.