Characteristics of High-Current Arcs Between Insulating Chute Materials

An experimental study has been performed to measure the fundamental characteristics of parallel rail arcs confined in polyester and glass mica slots. The voltage gradients of stationary arcs within polyester slots are higher than those for arcs within glass mica slots. The opposite characteristic was found for moving arcs. That is, moving arcs in glass mica slots produce the highest voltage gradients. For glass mica chutes the arc velocity is linearly dependent on current and inversely dependent on wall gap. Polyester wall materials result in overall lower arc velocities that increase with current at a rate that slows with increasing current. In addition, tests show that under certain conditions the arc velocity decreases significantly with decreasing slot width. The comparison of these arc characteristics is presented along with a description of the possible mechanisms controlling this behavior.