Abb Technology Ag

Ratan Das

John M Peterson

Mohamed Y Haj-Maharsi

Sethuraman Ganesan

The present invention is directed to a method and a system for fault detection analysis in a power device which is operatively associated with a differential protection unit. The power device has one input side and one output side through which an input current and an output current flows into and out from it, respectively. Signals representative of the input and output currents are processed in order to verify if an occurring fault is external to the power device. Under a condition of an external fault, the differential protection unit is disabled for a determined interval of time.

Method and system for through fault detection in electrical devices

A technique for dynamically determining the occurrence of a high impedance fault (HIF) independent of load. An HIF algorithm provides the energy value for a given number of samples of the input signal that is phase (load) currents and/or neutral (residual) current. The input signal energy value is multiplied by a factor that ranges from about 110% to about 300% to calculate a threshold energy value and the result of that calculation is stored in a buffer. A HIF detection signal is generated when the energy value determined for samples of the input signal that are the same in number as the given number of samples and taken after the given number of samples is greater than an energy value derived from a predetermined number of the calculated threshold energy values.

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Wilkes Barre, PA, United States of America

Ratan Das