Steady State Characterization of Arcing in 540 V dc Distribution Systems

As applications in aerospace, transportation and data centers are faced with increased electric power consumption, their dc operating voltages have increased to reduce cable weight and to improve efficiency. Electric arcs in these systems still cause dangerous fault conditions and have garnered more attention in recent years. Arcs can be classified as either low impedance or high impedance arcs and both can cause insulation damage and fires. Low impedance arcs release lots of energy when high voltage becomes nearly shorted to ground. High impedance arcs can occur when two current-carrying electrodes are separated, either by vibration of a loose connection or by cables snapping. The high impedance arc decreases load current due to a higher equivalent load impedance seen by the source. This complicates the differentiation of a high impedance arc fault from normal operation. The topics of high impedance arc generation; characterization and modeling; and detection have all been studied in the literature for system voltages below 300 V dc. This paper presents new findings in each topic for system voltages up to 540 V dc. Previous arc generation methods use either stepper motors or vibration tables for electrode separation. A spring-based arc generation method is proposed to better emulate a cable snapping. Based on the new experimental parameters, an improved empirical model of steady state arcing is presented and compared with previous models. The results attained here establish the basis for a future comprehensive study of high impedance arc characteristics for emerging applications in aerospace vehicles, transportation and more. Finally, wavelet and statistical detection methods are evaluated for this new data.