Arcing fault detection in underground distribution networks-feasibility study

In some circumstances, arcing faults on insulated low-voltage conductors can sustain or reignite intermittently for several or even several dozen minutes, generating large amounts of heat and gases. In underground secondary distribution cables in ducts, the decomposition gases escape to the ends of the duct, typically manholes, where they can ignite fire or explode, throwing out the manhole cover. Detection of arcing faults may be difficult using standard overcurrent protections because some arcing faults generate relatively low currents. To study the feasibility of detecting arcing faults in underground networks, personnel from Consolidated Edison Company of New York, Inc., New York, NY, conducted an experiment in one secondary network by staging arcing faults and collecting data at the fault location and several nearby vaults. The data were analyzed to examine the feasibility of developing a detection algorithm. This paper presents some results of this analysis in time, frequency, and time-frequency domains.