Importance

Loading Importance Indicators...

Abstract

A system is disclosed for sequentially disconnecting multiple phases of a first power source (12) from an electrical load (14) requiring a minimum of interruption and connecting a second power source (28) to the electrical load. A first embodiment of the invention disconnects immediately the phase in which a trip condition requiring disconnection of the first source power is detected and disconnects phases of a first power source (12) in which a trip condition is not detected upon the detection of zero current flow in those phases. In a second embodiment of the invention, each of the phases of the first power source (12) is disconnected immediately from the electrical load (14) upon the detection of a trip condition in any one of the phases requiring disconnection of the first power source. In both embodiments of the invention, the phases of the second backup power source (28) are connected upon the detection of the occurrence of zero voltage points in the respective phases. One of the features present in this system is an inhibiting signal which is created when the second backup power source, not on line, goes bad which prohibits a disconnection of the first power supply from the electrical load.

Loading the Abstract Image...

First Claim