Joliet Technologies Blog Variable Speed Drives – Myths and Facts

There is a good deal of knowledge, and more than a little misperception, about the use of variable speed drives (VSDs). The term “variable speed drive” encompasses both variable frequency drives (VFDs) used for controlling AC asynchronous and synchronous motors, and DC variable speed drives for controlling DC motors. In either case, determining if and when to use a drive will be much easier once the facts and myths about these controllers are clear. Let’s examine some of the more prevalent ones. Myth: “My process flow application is already controlled by control valves, so I don’t need a VFD.” Fact: In many cases, a VFD can more accurately control flow while reducing power consumed by the pump motor. If the flow control valves (FCVs) are being used mainly to throttle flow, you could instead use a VFD to reduce the speed of the motor, thus […]