Evaluating capacitor-switching devices for preventing nuisance tripping of adjustable-speed drives due to voltage magnification

Nuisance overvoltage tripping of pulse-width modulated adjustable-speed drives, due to switching of shunt capacitor banks at a utility's substation and the subsequent voltage magnification which can occur at an industrial customer's utilization-voltage bus, is discussed. Adjustable-speed drive design considerations affecting transient overvoltage ride-through capability are identified and discussed. A comparative evaluation of three switching devices equipped with transient overvoltage control, namely, circuit breakers with pre-insertion resistors, circuit switchers with highly damped pre-insertion inductors, and controlled closing devices, is presented.