Aep Energy Services, Inc.

Robert C Carruth

Eugene L Fromholtz, Deceased

Stanley K Farlow

Eric J Beltz

A method and system for indicating the position of a nuclear reactor control rod which is suspended from a shaft sliding vertically inside a travel housing. Primary and secondary coils are wound around the travel housing and an AC current travelling through the primary coil induces a secondary voltage across the secondary coil and a primary voltage across a secondary coil of an isolation transformer. The primary and secondary AC voltages are low pass filtered, rectified into DC voltages, and low pass filtered a second time. The secondary DC voltage is divided by the primary DC voltage and a ratiometric signal is produced. The ratiometric signal is compensated by decoupled zero and span adjustments and by a temperature compensation adjustment. A linear correction offset is calculated from data stored in an EPROM and summed with the ratiometric signal yielding a module output signal which is a linear representation of the control rod position.

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Worthington, OH, United States of America

Robert C Carruth