Hollow composite insulators are being used in railway transportation. These insulators have a central glass reinforced polymer (GRP) tube and many other materials such as an elastomeric housing (silicone, Ethylene-Propylene Diene Monomer EPDM, Ethylene Vinyl Acetate EVA, etc.) and metallic elements (connections, copper braids, etc.). The durability of hollow composite insulator is affected by structural and external environmental factors and is subjected during service to a large range of electrical, physical and chemical stresses.
The experimental results of the above study correlated to the premature failure of hollow insulators and the formation of corona discharges. These discharges were detected at triple point junctions of the metal fitting – dielectric – and air and created Ozone. Ozone, a highly oxidizing gas, corroded the metallic parts and induced the mechanical breaking of the Nitrile piston seal, known for poor Ozone resistance. Such results ascertain the need for routine inspection with DayCor® Rail.