A. B. Chance Company

Vance B Martin

Melvin B Goe, Jr

George D Allen

Harold D Haubein

Kenneth A Toeniskoetter

A rigid, unitary, externally mounted combination bus bar and current interrupter especially adapted for protecting pad-mounted transformers from the effects of fault currents is provided which precludes catastrophic transformer failures by ensuring that all energized parts within the transformer tank are on the protected load side of the current interrupter while also providing an external, insulated bus bar having strategically spaced, line-connecting, loop feed bushings which preclude arcing-over therebetween and permit the transformer to be safely system-installed according to established practices with preexisting feeder lines. The assembly preferably includes a rigid, encapsulated bus bar carrying a central conductor which electrically connects the spaced terminator-receiving bushings thereon in order to define an external electrical feed loop, with an integrally attached, oil-submersible high-range current limiting fuse extending from the bar and into the tank of the protected transformer. This construction permits safe, desirable double-fusing of the transformer with a series-related internal low-range expulsion-type fuse in order to enhance overall system coordination and ensure that only the easily replaceable expulsion fuse operates in the case of normally encountered low-range faults.

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Charlotte, NC, United States of America

Vance B Martin