NEMA Design E motors and controls

Abstract

While considerable information has been published on the new NEMA design "E" motors themselves, little attention has been given to the associated equipment used to control them. This paper first discusses the motor design and related topics and then moves to the unique issues that Design E motors present to the control and protection devices used with them. Issues to be covered include: the characteristics of NEMA Design E motors; the impact of the 1997 Federal Mandate on energy efficient motors; UL and NEC ramifications on control and protection equipment for use with NEMA Design E motors; and the potential for nuisance tripping of overload relays and instantaneous circuit breakers when used on Design E motors.