The high current arc ignition test

A description is given of the high-current arc test, which has been under study at the NEMA/UC Insulation Laboratory for several years. In a previous paper a number of difficulties in performing the test by Middendorf (see IEEE Trans. Electr. Insul., vol.EI-17, no.5, p.429-33, 1982). One was the difficulty in seeing the candle-like flame of the burning insulation immediately after the white-hot arc disappears. The dark-glass shield supplied with the tester does nothing to resolve the great difference in luminosity of the arc and the insulation flame. In order to eliminate this problem, a liquid-crystal light attenuator was developed. Another major contribution has been the addition of a digital arc energy meter. Consistent results are now obtained.<>