Westinghouse Electric Corporation

Ronald M Stefanick

Edward J Cham

A power transformer having a magnetic core winding assembly disposed within a casing, which contains multiple sensing means to sense abnormalities in fault conditions of the transformer, and an annunciator, having electro-mechanical relay circuits responsive to the sensing means for energizing an alarm circuit. The electromechanical relay circuits are arranged to provide two or more alarm point indication circuits, a pulse circuit and a bistable switching circuit adapted to energize external protective apparatus. The pulse circuit translates one or more sensing means signals of undetermined duration to a single 'pulse' signal of predetermined duration. This pulse signal is used to control a switching circuit with a contact connected to operate external protective devices such as an audible alarm. The pulse circuit provides for isolation of the indication circuits from the switching circuit such that each may be reset independently of one another. This provides the annunciator with the capability of silencing an audible alarm without interfering with the ability of the annunciator to respond to another abnormal condition by energizing the audible alarm circuit. The electromechanical relay annunciator is capable of operating with the high voltages and vibrations encountered in the operation of power transformers.

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Hubbard, OH, United States of America

Ronald M Stefanick