DC under voltage

What does 8 mean?

If the intermediate circuit voltage (DC link) drops below the under-voltage limit, the frequency converter checks for a 24 V DC back-up supply. If no back-up is connected, the unit trips after a fixed delay. This condition can lead to unexpected shutdowns and loss of motor control.

• Significant voltage sag or complete loss of one or more phases in the incoming AC mains supply.
• Tripped upstream circuit breaker or blown fuses on the drive's input power lines (L1, L2, L3).
• Loose or high-resistance connections at the drive's input terminals, leading to voltage drop under load.
• Absence of a 24VDC backup supply connection to terminals 12/13 when required during a main power loss event.

Click steps to track your progress.

1. 1

   Measure the incoming AC mains voltage at terminals L1, L2, L3 to verify it remains above the minimum specified operating voltage during operation.

2. 2

   Inspect all fuses and circuit breakers in the supply path to the drive; replace blown fuses or reset tripped breakers.

3. 3

   Tighten all power wiring connections at the drive's input terminals (L1, L2, L3) and inspect for signs of arcing or corrosion.

4. 4

   If 24VDC backup is used, verify the backup supply voltage at terminals 12 and 13, and check its current capacity against drive requirements.