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Why is my ATV61/ATV71 drive running faster than my speed reference?

Issue:
Customer has their low speed set at 20.0Hz and is using the HMI for the speed reference.  Drive consistently runs 20.0Hz above the frequency reference displayed on the screen.

Product Line:
ATV61/ATV71

Environment:
All models, All serial numbers

Cause:
Drive does not follow the given frequency reference but runs at a fixed offset speed above or below the given reference.

Resolution:
Under menu 1.7, Application Function, sub menu Reference Operations, Check to see that reference summing, subtraction, and/or multiplication is not enabled.  If any of these functions are enabled then a mathematical function is being performed between two or more speed reference channels to arrive at the final frequency reference applied to the drive.    In this case, Input summing between the HMI and AI1 was enabled. Since the Low Speed setting was set to 20.0Hz, the input of 20.0Hz. was being added to the frequency reference set by the HMI.   Disabling input summing corrected the issue and the drive then operated as expected.
 
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