DC Bus Undervoltage

What does Uv1 mean?

The DC bus voltage fell below the undervoltage detection level (e.g., ~190V for 200V class, ~380V for 400V class) while the drive was running, or specific parameter conditions were met. Common causes include input power phase loss, loose wiring, unstable voltage supply, or worn main circuit capacitors.

Additional Steps

Steps 1–2 are listed in Priority Fix.

1. 3

   Check the main circuit capacitor maintenance time (U4-05); if it exceeds 90%, consider replacing the control board or the entire drive.

2. 4

   Cycle power to the drive; if the fault reoccurs, inspect the soft-charge bypass relay or contactor and its performance life (U4-06). Replace the control board or entire drive if U4-06 exceeds 90% or the component is faulty.