Moist Tracking Investigation of Organic Insulating Materials

Moist tracking characteristics were determined for different classes of organic insulators, varying the electrolytes and electrolyte concentrations, conductor material, spacings, and temperature. The nature and concentration of an electrolyte and the conductor material were found to have a major influence upon an insulator's moist tracking behavior; the effect of conductor spacing was less pronounced, whereas temperature, up to 160°C, had a minimal effect only. Tracking was invariably associated with combustion. In agreement with prediction, aromatic polymers were observed to track at relatively low voltages, whereas compositions which decomposed by eatilization required high voltages to effect tracking. The response of a given insulator to changes in electrolyte, conductor material, and spacing appeared to depend solely on the chemical nature of the major constituent or constituents; the latter includes fillers.