F0003 Undervoltage fault in siemens micromaster 420 or MM420 drive - comes when line voltage failed or input supply voltage is less as compare to supply voltage of drive.
Cause - comes when line voltage failed or input supply voltage is less as compare to supply voltage of drive.
1. line voltage failed
2. shock stressing outside the permissible limits.
Diagnosis & Remedy please check the following:
1. The line supply voltage within the permissible range?
2. The line supply voltage stable with respect to sporadic failures and voltage dips (brown-outs).