Composite arc shields for vacuum interrupters and methods for forming same
The disclosed concept pertains to vacuum interrupters and arc-resistant shields. The arc-resistant shields are positioned in between a ceramic insulator. Each end of the arc-resistant shield is hermetically sealed to the ceramic insulator. The arc-resistant shield includes an outer surface and an inner surface. The inner surface includes an arc-resistant material. Disposed within the arc-resistant shield is a pair of electrode assemblies which are separable to establish arcing. In certain embodiments, the arc-resistant material is copper-chromium alloy.
1. A vacuum interrupter, comprising:
a first ceramic insulating portion having a first end;
a second ceramic insulating portion having a second end;
an arc-resistant shield having one end and an opposite other end, positioned between the first and second ceramic insulating portions, the shield constructed of a composite material, comprising:
a metal surface having an interior surface; and
an arc-resistant material on the interior surface of the metal surface, comprising:
a copper-chromium alloy,
wherein the copper-chromium alloy comprises copper selected from the group consisting of pure copper and copper alloy, and chromium alloy comprising ferrochrome, which comprises 70% by weight chromium and 30% by weight iron, and
wherein the arc-resistant shield forms an outer surface of the vacuum interrupter;
a first hermetic seal positioned on the one end of the shield between the metal surface and the first end of the first ceramic insulating portion;
a second hermetic seal positioned on the opposite other end of the shield between the metal surface and the second end of the second ceramic insulating portion;
an inner cavity formed by the arc-resistant shield; and
first and second electrode assemblies disposed in said cavity and being separable to establish arcing.
2. The vacuum interrupter of claim 1 , wherein the first and second ceramic insulating portions and the arc-resistant shield are cylindrically shaped to form a tubular structure.
3. The vacuum interrupter of claim 1 , wherein the vacuum interrupter further comprises a first end seal connected to the first ceramic insulating portion and a second end seal connected to the second ceramic insulating portion.
4. The vacuum interrupter of claim 1 , wherein the copper-chromium alloy comprises about 10 to about 60 weight percent chromium and balance copper based on total weight of the alloy.
5. The vacuum interrupter of claim 1 , wherein the metal surface is composed of a material selected from the group consisting of stainless steel, copper, steel, nickel-iron, cupronickel and mixtures thereof.
6. The vacuum interrupter of claim 1 , wherein the arc-resistant material is co-formed within the metal surface.
7. The vacuum interrupter of claim 1 , wherein the arc-resistant material is in a coating form and is deposited on the interior surface of the metal surface to form a layer thereon.