Design and application considerations for motors in steep-fronted surge environments

A large body of research has been conducted in the past 15 years into steep-fronted surges in electrical systems and their propagation in AC machine windings. This paper reviews the nature of the surge, the factors that determine its amplitude and rise time, and how it affects the motor winding. It then explains how its harmful effects can be controlled by system and winding design and by effective quality control. Related national and international standards are discussed and their shortcomings pointed out. Uncertainties in the prediction of amplitude and rise time of surges are explained, and guidance for cost effective specification of motors for application in a surge environment is given.