Protective relay circuit for detecting arcing faults on low-voltage spot networks

Abstract From the Canadian patent

A protective relay for detecting power arcing faults on a low-voltage spot network. The protective relay can monitor the voltage difference between each phase conductor, the voltage difference between each phase conductor and the neutral conductor, or the current on each phase conductor. Using one of these three sets of values, the protective relay first filters the input signal so that only frequencies indicative of a power arcing fault on the low-voltage spot network are analyzed. The signals passed by the filter are amplified rectified, and averaged and the peak of each signal detected. If the peak has a duration longer than a predetermined value a, fault indication is provided.