Westinghouse Electric Corporation

William L Miller

James F Sutherland

Redundant trip logic microprocessors produce partial trip signals which are voted on by a pair of voters at the power interface to the actuated devices. The logic implemented by each trip logic processor is straight-forward and can be designed for each individual plant. Also included is an automatic tester and testing method which can confirm the accuracy of A/D converters, digital inputs, check the trip points of bistable, verify all the trip and voting logic, and measure the time response of each channel. The test subsystem uses a microcomputer to control the isolation of the analog field sensor signals and digital contact signals from the analog and digital inputs, control the generation and/or injection of various combinations of reference and test signals, and monitor the response of the trip logic processors and voter to the test signals.

Auxiliary reactor protection system

A power interface circuit periodically which receives test pulses to test the operation and connections thereof. Voltage and current sensors detect the result of the testing and may be used for zero-crossing detection when AC powered devices are controlled by the power interface circuit. Preferrably, asymmetrical pulses, such as those representing an ASCII character, are used as the test pulses. Three input signals are received by the power interface circuit which performs two out of the three voting on the input signals to generate a control signal for two power switches. The power switches may be connected in parallel or in series to provide additional fault tolerance.

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West Deer Township, PA, United States of America

William L Miller