Abstract
Gases released from polymers placed near a burning electric arc are known to influence the behavior of the arc. In switching equipment, such ablation materials can be used to improve the interrupting capability. Current interruption experiments have been carried out with the purpose of comparing the arc-quenching capabilities of four common polymers. The test setup has static electrodes and two ablation polymer plates placed in parallel on both sides of the arc. Each ablation material is tested according to an “up-and-down” procedure that determines the current magnitude giving 50% probability for successful interruption. Current is supplied from a capacitor unit, and a sinusoidal waveform is created by means of a damped RLC circuit. The electrodes and the ablation materials are replaced after each interruption test. Polypropylene shows the best arc-quenching performance among the tested materials and interrupts about 2.7 times as high current as polyetetrafluoroethylene (PTFE), which is used as a reference material due to its low gassing. Polycarbonate and poly(methyl methacrylate) also greatly improve the current interrupting properties, interrupting a 2.2-2.3 times higher current compared to PTFE. As also pointed out by others, the arc-quenching capabilities of the polymers seem to increase with an increasing content of hydrogen in the ablation polymer. © Copyright 2013 IEEE - All rights reserved