抄録
This paper describes on a diagnostic method using gas analysis for terminals in aged 66-77kV XLPE cable lines. It was revealed from fundamental experiments and gas analysis of 45 terminals in actual XLPE cable lines that acetylene was particular gas produced by discharge at interface areas in terminals and the most suitable gas for diagnosis. It was cleared from the results of gas analysis and dismantlement carried out for another 96 terminals that a large amount of brownish-red deposits including black ones were observed at the interface area between XLPE and pre-molded insulations for terminals with high concentrations of acetylene gas, which strongly suggested the generation of partial discharge at that area. It was also found from the correlation between gas-analysis and dismantlement results that concentration of acetylene gas increased rapidly with degree of aging degradation, which showed that acetylene gas analysis was applicable to deterioration diagnosis for aged terminals in actual XLPE cables. In addition, easy and safe on-site gas sampling was established with the installation of a gas cock in metal casing of the terminal.
