What should be checked if an Altivar 61 or 71 display is showing 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 check for loose connections of ribbon cables inside the drive. 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.