VFD vs VSD: Are They The Same?


By Gary Patterson, Municipal Market Manager To answer that question simply: yes and no. Though, that’s not quite so simple, is it? As with most explanations, there’s a short answer and a long answer when we compare Variable Frequency Drives (VFDs) with Variable Speed Drives (VSDs).  Variable frequency drives are variable speed drives but there are other types of variable speed drives. The most common is Eddy Current. There are two significant differences, however, and this is the short answer:  Eddy current drives change the speed of the coupling while leaving the motor speed to run at full speed.  VFD’s change [...]