Flame Suppression Technique in Arc Tracking of Circuit Boards

Abstract

The problem of arc tracking in power electronic enclosures was studied through simple bench-top experiments aimed at understanding the phenomenon. Experiments were performed to isolate the causes of arc tracking on PCB boards with high-powered electrodes subjected to a Solventol/water mixture contamination. These experiments show that a minimum electrode spacing of 1 mm would be susceptible to arc tracking. A larger spacing of 3.2 mm appears to prevent arc tracking. In the event that arc tracking causes combustion, a passive flame suppression method is indicated. This method comprises of four layers of off-the-shelf expanded metal network. Tests show that the flame is quenched in about one minute, with minimum damage to the plastic enclosure.

Arc Tracking Control in Insulation Systems for Aeronautic Applications: Challenges, Opportunities, and Research Needs

“…This problem, typical of high-voltage systems, has also been described in 120/240 V AC systems [32]. The charred polymer becomes conductive, being able to sustain a short-circuit arc, which may spread along the wire due to a continuous pyrolyzation of the insulation material, leading to the arc tracking effect [41] due to the formation of a conductive carbon path along cracks within the insulation. In the case of multiple wire bundles in a harness, the insulation layers of other wires within the bundle may also become thermally carbonized or charred, thus starting to arc track, and ultimately leading to a complete fault of the entire bundle or even the harness [42], producing a massive current leakage and leading to the flash-over [43] and ultimately resulting in severe functionality loss [44].…”

“…When the discharge develops with a sufficient length, it can evolve to flashover. These short duration short-circuit arcs between a faulty polymeric insulated wire and another wire [40] can partially pyrolize (thermal carbonization) the insulation [41], thus generating an electrical conductance along the surface of the insulation. Small leakage currents flowing across the contaminated area degrade the base material, producing arc discharge, charring or igniting combustible substances nearby the arc.…”

“…Because of the electric resistance of the carbon path, the temperature along the conductive path increases due to the localized heat generated by the flow of a leakage current, thus pyrolyzing the insulation. Despite the small size of arcing, it can ignite combustible gases produced on the surface [41]. Arc tracking occurs because the polymer surface becomes conductive, heating up the polymeric material and finally causing ignition [46].…”

Tracking Resistance in Polymeric Insulation Materials for High-Voltage Electrical Mobility Applications Evaluated by Existing Test Methods: Identified Research Needs

“…This, in turn, raises the temperature of the insulation and causes further thermal degradation. Despite the small size of the arc, it can ignite the flammable gases that are produced on the surface of the insulation [ 64 ]. As the arcing activity continues, the new discharges expand the area of the existing conductive tracks, facilitating flashover or electrical breakdown [ 58 ], with the resulting fire hazard [ 65 ], with the resulting fire hazard [ 66 ].…”