The design and development of the shieldless vacuum interrupter concept

This paper briefly discusses the design and development of the shieldless vacuum interrupter concept as conceived by Vacuum Interrupters Limited (VIL) in London in the early 1980’s. The introduction of the shieldless concept was a radical departure from all previous designs and was driven by a change in design philosophy. Previously vacuum interrupter designs were complex and used a complicated multistage manufacturing process. The new design philosophy reduced the man-hours required to manufacture a vacuum interrupter by over 50% and reduced the number of components to be assembled (excluding braze material) from 16 to 7 . The success of the design is shown by the fact that over a quarter of a million devices have been manufactured to date by GEC (later ALSTOM, then AREVA) plants around the world, and after twenty years the shieldless design is still in manufacture, unchanged.