Leakage current test and study of room temperature vulcanizing coatings for outdoor high voltage porcelain insulators

This paper presents the result of a three-year on-site test using an on-line data acquisition system to monitor leakage current activities of 30 specimens. The on-site testing voltage source applied on the specimens is established in accordance with IEC 507 sec. 6-2. Insulators prepared for the specimens are 69 kV, post type and made of ceramic material. Three vendors of international RTV coating products compete heavily and controversially. Finally in this test, two vendors commit to apply their products on the bare surface of specimen-insulators in four different areas, namely: whole, upper-half, lower-half and none (bare). In addition to the end of the three-year leakage current test, flashover voltages of the aged specimens are undertaken in a high voltage test laboratory. The test results of leakage current trends, cumulative leakage charges and flashover voltages are compared in order to study relative performances in suppressing leakage currents.