Investigation of composite insulators with microvaristor filled silicone rubber components

This paper reports possible applications of microvaristor filled silicone rubber at composite insulators. Different insulator variations fitted with microvaristor filled sheds or shanks have been investigated. The insulators are dimensioned for U m = 170 kV and U m = 420 kV. Different variations of the 420 kV type were tested for their a.c. behaviour under artificial rain. In these tests the insulators with microvaristor filled silicone rubber components showed interesting properties. The suitability of microvaristor filled silicone rubber for application both in the sheds and in the sheath are discussed based on these positive results. The applicability for outdoor applications is investigated by an "inclined plane test" (material test) as well as by a "weather ageing test" under salt fog (material and design test).