Importance

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Abstract

A high voltage bushing has a central conductor which is surrounded by an insulation bushing core. The outer end of the conductor is bare and extends beyond the end of the bushing core. A mounting flange is also secured to the bushing core. One end of a hollow porcelain weathershed is fitted over the outer end of the central conductor and bushing core and seats against the mounting flange and defines an annular volume between the interior of the porcelain weathershed and the exterior of the bushing core. The bushing core is tapered down toward its end so that the annular volume within the weathershed has a tapered outer surface. The free end of the porcelain weathershed receives a bushing cap which seals the annular volume and can be bolted against the porcelain weathershed by a nut which is threaded onto the outer end of the conductor. The sealed volume is filled in situ by foaming a foamable material within the sealed annular volume, with the sealed volume serving as a mold to confine the foam form which is produced. The foam form is of a self-supporting, but slightly compressible, high dielectric material with foam cells filled with sulfur hexafluoride. A relief opening in the bushing cap permits excess foam to be released from the interior volume during the foaming process. The free-standing foamed body can be removed from the volume and replaced during maintenance or replacement of the bushing. The weathershed can be removed from the bushing core to allow easy removal and replacement of current transformers.

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First Claim