Cause : DC under voltage comes when the intermediate circuit voltage (UDC) is lower than the inverter’s Undervoltage limit the inverter will be switched off until the UDC once more goes above the undervoltage limit.

1. If the UDC remains under the undervoltage limit, the inverter will trip after a set time.
2. The time depends on the device, and is set at 2 - 15 sec.
3. An undervoltage can occur when the connected mains voltage is too low.
4. Check whether the supply voltage is suitable for the frequency converter, see Technical data.
5. When the frequency converter is switched off a alarm 8 (and alarm 6) is displayed briefly and a trip reset is generated.
6. Note: Voltage warning low (warning 6) will thus also be able to generate an alarm 8.