Otis · DSD 412 Elevator System
The Phase Locked Loop has lost synchronization with the 3 Phase AC input power supply. This sets the Severe Fault flag and forces the current reference to zero, shutting down the drive. It is generally caused by AC input power problems and is often self-correcting, frequently occurring with an F904 fault.
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Inspect the 3-phase AC input power supply for stability and proper voltage.