Development of directly molded bushings and cable sealing ends

Demands that electric power apparatus, and other types of industrial and domestic apparatus, be light and of low cost have been increasing recently. For electric power equipment such as bushings, simple structures with short assembly times are also demanded. Since conventional bushings are made of porcelain and contain oil for internal electrical insulation, they are very heavy, do not withstand earthquakes well, and pose risks of environmental pollution if broken. As described in News from Japan in the January/February 2013 issue [1], polymer-housed electric apparatus showed much better antiseismic performance than porcelain-housed apparatus in two big earthquakes that hit Japan in July 2007 and in March 2011. Consequently, demands from Japanese power utility companies for bushings with strong seismic resistance have increased sharply. In response, SWCC Showa Cable Systems Co. Ltd., Tokyo, has developed prefabricated polymer-insulated bushings and cable sealing ends.