What should be checked if an Altivar 61 or 71 display is showing NLP?
Drive displays 'NLP'
NLP indicates that no line power is present on the L1, L2 & L3 input terminals of the drive controller.
Check voltage at the L1, L2 & L3 terminals.
Check for open circuits on line contactors, circuit breakers, disconnect switches, or fuses.
If NLP state does not change with correct voltage present on L1, L2, & L3, remove the control board and check for loose connections of ribbon cables inside the drive.
WARNING: This step should be performed while the drive is powered down, and proper personal protective equipment should be worn.
For example: In an ATV71HC25N4 a customer found a loose X3 connector from the control board to the board behind and above the control board. This connector was on a ribbon cable that was about 1 inch by 1 inch. Drive ran OK after this was reseated.