Supplying MV motors from LV adjustable speed drives

In some cases where a medium voltage motor is to be used in an adjustable speed application, the system design, equipment availability, or other factors might favor supplying the motor from a low voltage system by way of a step-up transformer. While simple in concept, the use of a transformer to step up the drive output voltage to medium voltage level is not a common practice. This paper discusses characteristics of the drive, transformer, and load that affect system performance. Using a case study for a pump application, this paper develops a method using voltage drop and starting torque calculations to analyze the system.