Arc fault detection equipment and method using low frequency harmonic current analysis

摘要

An arc fault detection circuit includes a current sensing circuit coupled to a line conductor carrying a current. The current sensing circuit operates to sense current and output data indicative of the sensed current. A processing circuit implements a frequency transform algorithm to transform the output data to frequency data in a low frequency range and with a high spectral resolution where a minimum short time observation window is concerned. The processing circuit identifies an arc fault condition on the line conductor by identifying differences in said frequency data between at least two subsequent observation windows and identifying characteristics which exceed thresholds.

主权项

1. An arc fault detection circuit, comprising:
a current sensing circuit configured to be coupled to a line conductor carrying a current, sense said current and output data indicative of said sensed current; and a processing circuit configured to transform the output data to frequency data for frequency components of said sensed current in a low frequency range, said processing circuit further configured to identify an arc fault condition on the line conductor by identifying differences in said frequency data between at least two observation windows; wherein the identified differences comprise a plurality of difference measurements including a first group of difference measurements and a second group of difference measurements, said processing circuit further configured to identify a possible arc fault condition if any difference measurements of the first group exceed their corresponding threshold, and further confirm the arc fault condition if a majority of the difference measurements of the second group exceed their corresponding thresholds.