What effect does STEMS have on motors with a variable frequency or variable speed drives?
A. STEMS improves the quality of the power supplied to a VFD or VSD. STEMS will make these drives last longer. STEMS must be installed upstream of the VFD or VSD, or it will have adverse effect on the drive output, as the frequency changes on the output are significantly lower than the STEMS bandpass range. In addition, the savings will be less than on motors without these drives. We still make our 5% savings, but it is on a smaller load, with less wasted power, due to the VFD or VSD.
