Toshiyuki Kuroyagi

Development of line post type polymer insulation arm for 154 kV

Based on the results of basic studies on the housings and FRP cores of polymer composite insulators, a line post type polymer insulation arm for 154 kV with a truss structure formed by three polymer insulation arm units, i.e., two horizontal units with an open angle between them and one suspension unit, was experimentally manufactured. Samples of the polymer insulation arm were tested to verify the withstand voltage performance under polluted conditions, the impulse and power-frequency withstand voltage performance, and the mechanical performance by a full scale test against longitudinal loads.

Evaluation of time variation of hydrophobicity of silicone rubber using dynamic contact angle measurement

Dynamic contact angle measurements based on the Wilhelmy method were performed to evaluate the time variation of hydrophobicity of silicone rubber. The technique can determine both advancing and receding contact angles of a plate sample and evaluate the change of hydrophobicity in a short time. By changing the immersing time of silicone rubber into water, some aspects of overturn and/or re-orientation of polar groups at the surface were observed as a change of the contact angle. Also, the contact angle of silicone rubber was compared with that of fluorinated silicone rubber.

Mechanical characteristics of line post type polymer insulation arm for 154 kV

This paper describes the mechanical characteristics of a 154 kV line post type polymer insulation arm that functions both as the steel arm and as the porcelain insulator of the currently used steel transmission towers. The 154 kV line post-type polymer insulation arm consists of polymer composite insulators, called units, that include two horizontal units with an open angle, to respond to a longitudinal load of 40 kN, and a suspension unit to respond to a vertical load. Its installation length is about 2.3 m. Samples of the insulation arm were installed at different places on an electric wire to form a truss structure and a frame structure, in order to examine their mechanical characteristics. For the truss structure, neither remarkable bending stress nor torsional stress was observed in the FRP core. The mechanical force design of the insulation arm can be evaluated in reference to the axial force of the FRP core only. The buckling coefficient, for evaluating the axial force of the insulation arm with the truss structure, was experimentally identified. Moreover, we were able to show that a static load test, for evaluating the mechanical force performance of the insulation arm against a longitudinal load, is more severe than an impact load test at the same longitudinal load. ©1998 Scripta Technica, Electr Eng Jpn, 126(2): 23–30, 1999