The chemistry of insulation tracking with copper electrodes

The mechanism of insulation failure when copper electrodes are used for the comparative tracking index test was investigated. It was found that exothermic reactions initiated by the scintillation increase the intensity of the microarcs. The observation of color difference between test sites where failure occurred and test sites where there was no failure when using copper electrodes as well and increase in the brightness of scintillation when copper was used led to the hypothesis that Cu/sub 2/O released by the electrodes and spread out over the insulation surface is oxidized to CuO. This hypothesis was confirmed by performing tests in which platinum electrodes were used on insulation surface covered with a layer of commercially prepared Cu/sub 2/O.<>