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What can cause an ULF motor underload fault on the ATS48 soft starter?

Published date: 10 June 2020

ATS48 tripping on ULF or motor underload fault.

Product Line:
Altistart ATS48


The soft starter is programmed for activation motor underload (ULL) in the Pr0 menu.
The motor underload threshold parameter (LUL) is set to 60% and the drive is running only 58% or lower motor torque viewed in the SUP menu parameter (Ltr).

Check Motor underload threshold parameter (LUL) in menu PrO and compare it the motor torque parameter in the SUP menu.   If your LUL parameter is set lower then the Ltr in the SUP then the soft starter will trip on ULF fault.

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