The Development of a Suspension-Type Insulator

Increasing voltages employed in transmitting large amounts of power over long distances emphasize the need of a better line insulator for this purpose. This paper outlines the conditions under which a suspension-type insulator has been experimentally developed for such use. In the form described, it consists of metallic terminal members to suitably distribute the electric flux and an insulating, impregnated wood (or other material) mechanical strain member, concentric with the hollow electric field produced between the metallic terminal members. The unit described is designed for use on 110,000-volt power lines, two similar units in series for 220,000-volt lines and, when necessary, three units in series on 330,000-volt lines. The fundamental principles of the insulator are established and later continued experience in service may or may not modify detail.