Federal Pioneer Limited

Nxtphase Technology Srl

Perseus 2000, LLC

Glenn William Swift

Zhiying Zhang

Robert George Coish

Mark Anthony Weekes

An apparatus for monitoring and controlling the operation of an electrical power transformer includes a processor with input transducers for providing to the processor inputs indicative of electrical current in a winding of the transformer and ambient temperature outside the transformer. The processor is arranged using an algorithm based upon heat transfer to repeatedly calculate a first prediction, based upon the present values of electrical current and ambient temperature, of a time period before the hot spot temperature exceeds a pre-set allowable maximum and a second prediction, based upon the current value of power, of a time period before the accumulated loss of life exceeds a pre-set allowable maximum. If the shorter time period of the two calculations is less than a pre-set value, for example one half hour, the processor generates an alarm signal and a display counting down the time remaining in the period, together with a second alarm signal at a shorter second time of for example one quarter hour.

Apparatus and method for predicting an overload trip for an electrical power transformer

Apparatus for preventing thermal damage to an electrical power transformer

A ground fault detector for an AC circuit is responsive to resistive ground fault current but not to capacitive ground fault current. Current in the AC circuit is sensed and a corresponding signal current is produced. The direction of the signal current is reversed in each alternate half AC cycle without reversing the signal current in each intervening half cycle, the unreversed and the reversed signal current is averaged, and the presence of averaged signal current above a predetermined value is sensed to indicate significant resistive ground fault current.

Ground fault detector

Growing community of inventors

Winnipeg, Canada

Glenn William Swift