DC link voltage low

What does WARNING 6 mean?

The DC-link voltage is lower than the warning limit, which depends on the frequency converter's voltage rating. The unit remains active but operating at a reduced DC link voltage can affect motor performance or lead to an undervoltage trip.

• Low incoming AC mains voltage or significant voltage sag below 340V during heavy load transients.
• Loose or high-resistance connections on the incoming AC mains terminals (L1, L2, L3).
• Insufficiently sized or overly long mains supply cables, leading to excessive voltage drop under load.
• Overloading the frequency converter beyond its rated capacity, causing high current draw and voltage sag.
• Faulty input rectifier bridge or DC-link capacitor bank within the frequency converter.

Click steps to track your progress.

1. 1

   Measure the incoming AC mains voltage (L1-L2, L2-L3, L3-L1) under load and verify it is within the frequency converter's specified operating range.

2. 2

   Check for loose or corroded connections on the frequency converter's input terminals (L1, L2, L3).

3. 3

   Review the cable sizing for the mains supply to ensure it is adequate for the frequency converter's current rating and cable length.

4. 4

   Monitor the DC-link voltage on the frequency converter's display (parameter 16-01 DC Link Voltage) during operation to identify sag events.

5. 5

   Reduce the motor load or consider a higher-rated frequency converter if continuous low DC-link voltage is observed under normal operating conditions.