Concepts, Configurations, & Benefits of Motor Starting and Operation with MV AC Adjustable Speed Drives

Modern MV AC adjustable speed drives [MV ASDs] are frequently used for industrial process optimization and to provide energy savings over fixed speed solutions or mechanical ASD solutions. However for over 20 years MV ASDs have also be used to accelerate motors and their connected loads to line frequency equivalent speed and then connect them to the power grid. When properly done, this synchronized starting causes little impact on utility current or voltage beyond normal running values for the motor and load. This paper reviews the power system impact of starting large motors, and the broad topic of ASD synchronized starting. Other topics covered are system performance, equipment selection, relative economics and complexity.