Combination Motor Controller

Oct. 12, 2007
This white paper outlines the differences between Type E and Type F starters recently introduced by the revisions on UL508.
Combination starters are the most common type of packaged motor controllers. They are called combination because of their construction and combined functions required by the U.S. National Electric Code. UL recognizes six different constructions of combination starters that meet the requirements of a motor branch circuit. Types A through D are traditional starters that use either a listed disconnect switch and fuses or a listed circuit breaker as the disconnect means and for short-circuit protection. Each type uses a separate UL 508 listed motor controller and overload relay. Recently revisions on UL508 introduced the Type E and Type F starters. This white paper, by WEG Electric Motors Corp., outlines the differences.