Vaccum Switch Chamber with a Protective Sleeve that is Applied by Heat Shrinking

Abstract

A resin-encapsulated pole piece is provided and includes a vacuum interrupter chamber having an outer surface. A protective sheath covers the outer surface of the vacuum interrupter chamber. The protective sheath is composed of a heat-shrinkable material. The protective sheath has been pulled over the vacuum interrupter chamber and then heat shrunk so as to be in firm contact with the outer surface of the vacuum interrupter. An outer casing encapsulates the vacuum chamber covered by the protective sheath. The outer casing is composed of a cast epoxy resin and is in contact with the protective sheath.

1 . A resin-encapsulated pole piece comprising:
 a vacuum interrupter chamber having an outer surface;   a protective sheath covering the outer surface of the vacuum interrupter chamber and being composed of a heat-shrinkable material, wherein the protective sheath has been pulled over the vacuum interrupter chamber and then heat shrunk so as to be in firm contact with the outer surface of the vacuum interrupter; and   an outer casing encapsulating the vacuum chamber covered by the protective sheath, the outer casing being composed of a cast resin and being in contact with the protective sheath.   
     
     
         2 . The resin-encapsulated pole piece of  claim 1 , wherein the cast resin comprises an epoxy resin. 
     
     
         3 . The resin-encapsulated pole piece of  claim 2 , wherein the heat-shrinkable material has the property that it can be mechanically stretched and will remain in a stretched condition unit it is shrunk with the application of heat. 
     
     
         4 . The resin-encapsulated pole piece of  claim 3 , wherein the heat-shrinkable material is elastic, elastomeric or plastomeric. 
     
     
         5 . The resin-encapsultated pole piece of  claim 4 , wherein the outer surface of the vacuum interrupter chamber is cylindrical.