Horizontal series fault comparison in AC
Estes, Hunter Blake
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This research focuses on empirical observations of horizontal series arc faults. These faults differ from ground faults, for series faults encompass the electromagnetic transient effects of arc formations in series with sustained current flow when there is a break in the circuit. This may happen intentionally (as in a breaker) or unintentionally (as in a loose, damaged, or severed cable). This paper studies some of those transient effects during arc ignition, propagation, and cessation. Emphasis is on dc systems, for series faults present some of the more challenging safety concerns relating to widespread dc micro-grid acceptance and proliferation. However, arc behavior is also compared to that of ac systems under “quasi-equivalent”, passive circuit parameters. Variables of study primarily include arc voltage, current, and their relationship to electrode spacing under dynamic conditions. Results indicate that interruptions in dc current, while appearing more chaotic from a localized standpoint, do not produce the fast-acting transients associated with ac disturbances. Additionally, if dc arcs propagate over a slowly increasing distance of separation, they can be modeled as quasi-static in nature. An equation model is developed and curve-fitting parameters match well with historically tabulated constants.