Mains phase fault

What does 0x3120 mean?

This fault is triggered by a failure in one or more phases of the mains power supply. The inverter will immediately disable.

• Loss of one or more phases in the incoming AC supply to the drive due to tripped breaker, blown fuse, or utility fault.
• Loose or corroded connections at the mains input terminals (L1, L2, L3) of the inverter or upstream switchgear.
• Unbalanced mains voltage exceeding the permissible tolerance (e.g., >5% phase imbalance) causing the drive's detection circuit to trip.
• Faulty mains contactor or input rectifier section within the inverter, preventing proper sensing of all three phases.
• Transient voltage sag or brownout on the mains supply, especially during heavy load switching, causing momentary phase loss.

Click steps to track your progress.

1. 1

   Verify all three incoming AC phases (L1, L2, L3) are present at the drive's input terminals using a multimeter.

2. 2

   Check all upstream fuses and circuit breakers for continuity and reset any tripped devices.

3. 3

   Tighten all mains power connections at the drive (terminals L1, L2, L3) and upstream distribution panel.

4. 4

   Measure the voltage between each phase (L1-L2, L2-L3, L3-L1) and phase-to-ground, ensuring balance and correct voltage level.

5. 5

   Inspect the mains contactor for proper operation, checking auxiliary contacts if applicable.