Basler Electric Company

Sidney B Harden

Timothy M Wilkerson

Richard A Freeman

An apparatus for protecting an electrical power system supplying electrical power to an electrical load comprises a transformer for sensing an operating condition of the electrical power system and for producing an analog signal representative of the operating condition, and a microcomputer for periodically sampling the analog signal and for converting the analog signal into a series of digital signals. The microcomputer includes circuitry for deriving a digital value representative of a square root of the series of digital signals and circuitry for processing the digital value over time to determine a processed value which is a function of both the sensed operating condition and time. A circuit breaker is responsive to the microcomputer for disconnecting the power system from the load in the event that the processed value is not within preset limits. The microcomputer also generates a relay signal representative of the status of the relay and the relay includes an output port responsive to the relay signal, for communicating the status of the relay to a remote station.

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St. Louis, MO, United States of America

Sidney B Harden