A LABORATORY TEST FOR TRACKING AND EROSION RESISTANCE OF HV OUTDOOR INSULATION

A new laboratory test for evaluating the tracking and erosion performa nce of Hv outdoor polymeric insulating materials is described. The mat erials evaluated include various formulations of HTV (high temperature vulcanized) silicone rubber and polyolefin polymers. The test is base d on combining some features of the ASTM D2132 DF (dust and fog) test and the ASTM D2303 IP (inclined plane) test. The new test employs Ip t est geometry, rp test equipment, and Ip specimen plaques. The plaque i s coated with a mixture of clay and salt similar to the contaminant of the DF test and identical to the contaminant used in the IEC clean fo g test to rate ceramic insulators for use in contaminated environments . A liquid contaminant with a conductivity similar to that of the DF t est is applied to the test specimen in the same way as in the ip test. Data collected from the field on the maximum concentration of insolub le and soluble ionic materials on surfaces of contaminated insulators which have been for 21 years in contaminated regions, provide a basis for choosing the minimum concentration of the solid contaminant to app ly to the specimens. This choice also serves to define, at least tenta tively, the geographical area where the results of this test have sign ificance. It is expected that this test could be used also for screeni ng materials and obtaining a relative ranking of the tracking and eros ion resistance of various materials. Measurements of the leakage curre nt via a computerized data acquisition system, and the discharge activ ity with a high speed camera were performed, and have resulted in a be tter understanding of the onset of material degradation.