Arc erosion characteristics of cables with heatproof insulations in AC series circuits at low pressure

Abstract

Abstract The droplet diameter, dripping frequency, and arc bead appearances vary significantly with pressure. This study investigated the arc erosion characteristics of copper-core cable with mica insulation (HC0) and aluminum-core cable with PI insulation (HA0) at different pressures. During arcing of HC0, the diameters of dripping droplets decrease as pressure decreases, but the dripping frequency exhibits an increasing trend. The primary arc beads (PABs) of HA0 at atmospheric pressure are mainly globular arc beads. HA0 PABs at 60 kPa are mostly coral arc beads, which is attributed to the slow oxidation rate and easier outflow of liquid aluminum through cracks at low pressure. HA0 PABs have the characteristics of coral arc beads and gradual necking, which broadens the previous theory in accident investigations that coral arc beads and gradual necking are considered as physical evidences of fire globules and short-circuit melted marks. Besides, the influence of pressure on arc duration of HC0 and HA0 is revealed. This study could provide support for fire accident investigation and arc accident prevention.