Determination of Leakage Current through Dry Insulated Coating of 10 kV Overhead Transmission Line Wires in case of Their Contact with Trees and Other Earthed Objects

Abstract

Investigations that were conducted with the help of overhead transmission line model reflecting such situations as wire swinging cross, their contact with fallen trees and other earthed objects have shown that the overhead transmission line may operate rather long under such conditions. However leakage current may lead to dangerous high potentials on these objects and around them.The results of calculations and experimental research have revealed that in the case of dry surface of polyethylene coating of overhead transmission line wire leakage current on earthed object and insulation resistance is determined by object-wire capacitance and it does not depend on specimen length and object resistance. Leakage current does not exceed 1 mA and insulation impedance is not less than 50 Nffi for real overhead transmission line spans.