AI L1L2 Under Voltage

What does F36 mean?

This fault indicates an L1-L2 under-voltage condition (108 V equivalent based on F34 reference) detected by the anti-islanding protection, triggering a slow disconnect. This mechanism ensures the inverter disconnects from an unstable grid, protecting both the inverter and grid from potential damage due to insufficient voltage.

• Grid L1-L2 phase-to-phase voltage dropping below the equivalent of 108 V phase-neutral (e.g., approx 216V line-line for 208V system) for a sustained period.
• Widespread utility grid under-voltage condition, brownout, or high impedance feeder cable causing voltage drop across L1 and L2 phases.
• Inverter's internal L1-L2 voltage measurement hardware showing inaccuracies or component fatigue, leading to false low voltage readings.
• Anti-islanding parameter P_AI_L1L2_Volt_Min_Slow set too high, causing nuisance trips on minor grid voltage fluctuations.

Click steps to track your progress.

1. 1

   Using a true RMS multimeter, continuously monitor the L1-L2 phase-to-phase voltage at the inverter's input terminals over several hours to observe any sustained readings below the expected 108V equivalent.

2. 2

   Compare the measured L1-L2 voltage values against the inverter's configured anti-islanding slow trip threshold (e.g., P_AI_L1L2_Volt_Slow).

3. 3

   Inspect the integrity of the AC input cabling from the grid connection point to the inverter (e.g., conductor termination, correct cable sizing).

4. 4

   Contact the utility provider to report sustained low voltage conditions on the grid and inquire about local power quality or ongoing maintenance.

5. 5

   If grid conditions are confirmed stable, consider adjusting the L1-L2 slow under-voltage parameter (e.g., P_AI_L1L2_Volt_Min_Slow) downwards slightly, if allowed by grid codes.