AC Output Under Voltage

What does F1 mean?

This Escalating Automatic Fault indicates an AC under-voltage shutdown (below 108 V). If it occurs 3 times in 2 minutes, it becomes a manual fault, meaning the inverter has repeatedly shut down to protect connected loads.

• Excessive load current exceeding inverter's continuous rating (e.g., motor startup with high inrush current).
• Inadequate AC output cable gauge (too thin) causing significant voltage drop under load.
• Faulty AC output contactor or breaker with high resistance connections, leading to voltage drop.
• Utility grid instability or brownout condition where the incoming AC voltage itself is low.
• Improperly configured inverter output voltage settings (e.g., parameter P3-10 set below 108V).

Click steps to track your progress.

1. 1

   Measure AC output voltage at inverter terminals L1, L2, L3 (or L1, N for single phase) using a true RMS multimeter while applying a controlled load.

2. 2

   Verify inverter output voltage configuration (e.g., Parameter P3-10, P3-11) against system requirements and local grid standards.

3. 3

   Inspect AC output wiring for correct gauge sizing according to NEC/IEC standards and potential loose terminations at the inverter, contactor, and load.

4. 4

   Monitor utility grid incoming voltage at the inverter input terminals (L1, L2, L3, N) using a power quality analyzer to detect brownout conditions below 108V.

5. 5

   Check for high resistance across AC output contactor poles or circuit breaker terminals by measuring voltage drop when current is flowing (should be < 0.1V).