DC UNDERVOLT

What does 3220 mean?

The intermediate circuit DC voltage is insufficient, typically due to a missing supply voltage phase, a blown input fuse, or an internal rectifier bridge fault. This condition prevents the drive from powering the motor correctly, leading to a shutdown or inability to start.

• Loss of one or more phases (L1, L2, L3) of the incoming AC supply voltage to the drive.
• Blown input fuses (e.g., F1, F2, F3) or tripped input circuit breaker (e.g., Q1) on the supply side of the drive.
• Insufficient incoming AC supply voltage (e.g., below 340V for 400V drives) due to sag or overloaded supply transformer.
• Failure of one or more diodes in the drive's internal rectifier bridge.
• Loose or corroded power connections at the drive's input terminals or supply contactor.

Click steps to track your progress.

1. 1

   1. Measure the incoming AC line voltages (L1-L2, L2-L3, L3-L1) at the drive's input terminals and verify all phases are present and at nominal voltage.

2. 2

   2. De-energize and lock out power, then measure continuity of all input fuses or verify state of input circuit breaker.

3. 3

   3. Measure the DC bus voltage at the drive's intermediate circuit terminals (DC+, DC-) and compare it against the expected voltage (e.g., ~560VDC for 400VAC input).

4. 4

   4. With power isolated, perform a diode check on the drive's internal rectifier bridge using a multimeter in diode mode.

5. 5

   5. Check all power wiring connections at the drive's input terminals, supply contactor, and main disconnect for tightness and proper seating.