James G. Biddle Company

Eugene Gilman

Jerry Frank

The present invention is a method of and an apparatus for measuring resistances of at least one transformer winding () in configurations of connected transformers windings. The method is based on increasing driving power from the source of electrical energy () until the current reaches a predetermined level, which is below the core saturation current level of the measured transformer or the measuring device current limit, and then controls the power of the source of the electrical energy to maintain predetermined current flowing through the at least one winding over a time period sufficient to cause a L di/dt contribution to a voltage drop across the at least one winding to decrease below a threshold level. The apparatus measures simultaneously the constant current flowing in the at least one winding and the voltage drop over the at least one winding after the predetermined time period has elapsed. The resistance of the at least one winding is calculated from the voltage drop over the at least one winding and the current flowing in the at least one winding.

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Southampton, PA, United States of America

Eugene Gilman