automatic transfer switch

automatic transfer switch

1. A combination of an electrically operated, double-throw transfer switch and a control panel. Under normal circumstances, the connected load is energized from the utility source. Upon failure of this source, the transfer switch automatically connects the load to an emergency power generator until power supplied by the utility is restored, at which time it reconnects the load to the utility source.

2. In an electric circuit, a switch which automatically transfers a specific load from the normal source to an emergency source if the former fails or if the voltage of the normal source drops below a preset minimum.

McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.