by Bill Brown, PE & Jay Guditis

An important requirement of mission-critical electric power distribution systems is the need for automatic operation. In particular, the rapid and reliable transfer of the system from one power source to another during certain system events is crucial to achieving the reliability goals for such system and the facility it serves. However, the design of such an automatic transfer system is all-too-often considered “less important” than many other aspects of the over-all power system design. The results of this can be far-reaching and, in some cases, catastrophic with respect to the reliability of the system. This paper outlines the design considerations for automatic transfer in the mission-critical power environment, and gives recommendations as to how these considerations can be reliably implemented into an automatic transfer system.