Rte Corporation

Michael J Estes

A relay for tripping a circuit breaker in a high voltage power line, the relay including a current transformer having first and second turns ratios, a heat radiation circuit including a plurality of lamps connected to the current transformer and a sensing circuit including a phototransistor which responds to heat radiation from one of said lamps, the turns ratios and lamps being selectively connectable to provide different minimum trip current levels of the relay.

Multiple range inverse time overcurrent relay

A temperature sensing transformer primary switch for a distribution transformer, the switch being mounted within the distribution transformer below the level of the dielectric fluid and being manually operable externally of the transformer for opening the primary circuit and deenergizing the transformer, the switch including a temperature sensing device mounted on the internal end of the transformer below the level of the dielectric fluid to open the primary switch in response to overload temperatures produced on the transformer's secondary circuit. The temperature sensing device includes a compression spring and a wax motor for releasing the energy stored in the compression spring as the temperature of the dielectric fluid reaches a predetermined maximum temperature. The spring is preloaded sufficiently by a manual operation to actuate the switch at the maximum temperature. A pressure responsive switch assembly is provided for opening the primary switch.

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Waukesha, WI, United States of America

Michael J Estes