Electrical and mechanical performance of porcelain suspension insulators removed from a 230 kV transmission line after 35 years of service

This paper presents the results of an experimental investigation into the electrical and mechanical characteristics of suspension insulators removed from a 230 kV transmission line after 35 years of service. The electrical characteristics of the insulators were evaluated by determining the 60 Hz dry flashover voltage of individual insulator units. The electrical characteristics of the insulator strings were evaluated by determining the 60 Hz dry withstand voltage, 60 Hz dry and wet flashover voltage, critical flashover voltage (CFO) using positive lightning impulse, and the radio influence voltage (RIV) at working voltage. All electrical measurements were performed at the Mississippi State University High Voltage Laboratory. The mechanical characteristics of the insulators were evaluated by determining the combined mechanical and electrical ultimate strength and the mechanical impact strength of individual insulator units