F157 fault in WEG CFW900 Drive indicates an IGBT Undertemperature. This means the internal components are far below their minimum rated operating temperature, triggering a safety trip.
Cause:
Fault of undertemperature measured by the sensors in the IGBTs, rectifier, power and/or control below -30 °C.
- Ambient temperature around the inverter ≤ -30 °C.
Remedy:
Check the installation environment. Provide heating element control inside the cabinet for operation in cold environments.
