Warning /Alarm 8 in VLT Micro Drive FC301/ FC302 : DC undervoltage - If the DC-link voltage drops below the undervoltage limit, the drive checks for 24 V DC back-up supply. If no 24 V DC back-up supply is connected, the drive trips after a fixed time delay. The time delay varies with unit size.

1. Check that the supply voltage matches the drive voltage.
2. Perform an input voltage test.
3. Perform a soft-charge circuit test