Vacuum switching device
AssigneeGEC Alsthom SA
InventorLeslie T Falkingham
Life of this patent
Estimating the term…
Abstract
In a vacuum switching device having first and second contacts, the first contact only is composed wholly or partly of a combination of at least a high-conductivity material and an arc-resistant material, e.g. chromuim, tungsten or tungsten carbide, and/or an anti-weld material, e.g. bismuth, antimony, tellurium or lead, while the second contact lacks the arc-resistant and anti-weld material. Metal vapor produced by the first contact during arcing is deposited on the opposing surface of the second contact to form a thin layer of high-conductivity and arc-resistant and/or anti-weld material which then dominates the properties of the arc and allows a low chopping current and/or an enhanced anti-weld performance of the contacts to be achieved without the expense of having both contacts of the same composition at manufacture.
Claims11
A vacuum switching device, comprising:
- a) first and second contacts movable relative to each other, for making and breaking an electrical circuit,
- b) said first contact being of one-piece construction and being constituted of a bulk material having a predetermined conductivity, and
- c) said second contact being of two-piece, welded construction and having
- i) a bottom piece constituted of a material having said predetermined conductivity, and
- ii) a top piece facing said first contact and constituted of a material having a lower conductivity which is less than said predetermined conductivity, the top piece also being constituted of an anti-weld material and an arc-resistant material.
A vacuum switching device, comprising:
- a) first and second contacts movable relative to each other, for making and breaking an electrical circuit,
- b) said first contact being constituted of a bulk material having a predetermined conductivity, and a vacuum-deposited layer on the bulk material and constituted of a material having a lower conductivity which is less than said predetermined conductivity, the vacuum-deposited layer also being constituted of an anti-weld material and an arc-resistant material, and
- c) said second contact being of two-piece, welded construction and having
- i) a bottom piece constituted of a material having said predetermined conductivity, and
- ii) a top piece facing said vacuum-deposited layer and constituted of said lower conductivity material, said anti-weld material and said arc-resistant material.
Dependencies are inferred from the claim text.