Investigating ways to prevent electrical arc flash

Koutoula, Sotiria and Timoshkin, Igor and Judd, Martin and Harrison, Emma (2015) Investigating ways to prevent electrical arc flash. In: 12th Petroleum and Chemical Industry Conference Europe, 2015-06-09 - 2015-06-11, The Tower Hotel. (

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Electrical arc flash hazard mitigation techniques focus on the reduction of hazard levels in an electrical power system. Analysis of arc incident energies pre- and post-mitigation to reduce hazard levels shows that risk control measures can lead to significant reductions in potential harm and damage should an arc flash occur. However, mitigation methods alone do not necessarily prevent arc initiation. This paper reports an investigation into the initiation of electrical arcs within the context of a study into new approaches to reduce the hazard posed by arc flash. In addition to the local physical arrangement of the busbars, onset of the arc is influenced by specific weaknesses or defects of the insulation system. However, the influence of these local factors diminishes once the arc is formed. Thereafter, arc current and the power dissipated in the arc depend both on the ability of the surrounding network to sustain the electrical discharge and on transient interactions between the impedance of the feeder network and the impedance of the arc itself. To study arc initiation with the aim of identifying factors that could reduce the likelihood of arc onset, measurements of short-term arc characteristics under various initial conditions are presented. Measurements primarily concern the time-domain transient voltage and current waveforms in an experimental configuration designed to allow variation of parameters that may influence arc initiation. These waveforms are captured on a nanosecond timescale so that the temporal development of arc power and impedance can be analysed as a function of different initiation mechanisms. Results are analysed to show how the impedance of the electrical driving circuit and the quantity of electrical energy stored in the circuit physically close to the arc affect the arc evolution and the magnitude of the power dissipated.