Electrical performance of cycloaliphatic epoxy materials and insulators for outdoor use

This paper reports the results of material tracking and erosion tests, and flashover tests of full-scale insulators made from epoxy compounds. Six different formulations, all based on the cycloaliphatic epoxy family, were evaluated as flat slabs and complete insulators rated for 25 kV (line to line) system voltage. In addition, line insulators in the range 11-66 kV, that had been operating satisfactorily for several years in light to heavy contaminated regions in different countries, were evaluated to obtain information on their future expected performance. Material tracking and erosion tests were performed using the standard ASTM D-2303 inclined plane test, and a variation of the same test that was developed in-house. Flashover tests were performed using the IEC Standard 507 “clean-fog” method. Results demonstrate that all material formulations evaluated had adequate tracking and erosion resistance for outdoor use. In addition, the insulators evaluated did not flashover at nominal service voltage (and higher) under a wide range of simulated contamination conditions. The overall good performance of the insulators has been related to material formulation, design and manufacturing of the insulators