DC auxiliary power system minimum and arcing ground faults in industrial facilities

Abstract

The importance of short-circuit current evaluation for the design of any power system, including DC systems, is very well known. Every DC system is subject to faults, in fact, short-circuits and ground faults can be expected at any point. Even if the maximum and minimum values are generally defined with reference to bolted-fault conditions, bolted faults are rare and the fault usually involves arcing and burning (impedance). Therefore, the limiting value of minimum short-circuit depends on the arcing fault. Since an uninterrupted DC arcing fault can cause significant power system equipment and building damage from the fire and smoke that can be produced (i.e., burning cable insulation), it is necessary to: identify critical fault points; estimate the modes and effects of these faults; examine ways in which they can be located; select the best protection methods to isolate the fault; mitigate system damage and outage time; and maintain personal safety. In addition, surveillance and system configuration management programs should be established to prevent the potential for arcing faults to occur. Finally, this paper discusses the extent of damage that can result from a DC arcing fault and recommends system and protection enhancements to significantly limit this damage.