Scissor-type disconnect switch with contact elements having wear-resistant armatures

In an electrical switch comprising a first contact element fixedly secured to a power line, and a pair of mutually symmetrical second contact elements constituting extremities of a pair of scissor arms operable to grip said first contact element between them for connecting said power line to a load circuit,

• the improvement wherein said first contact element comprises a metallic supporting rod of cylindrical shape with a reduced-diameter longitudinal cylindrical section and a pair of wear-resistant conductive part-cylindrical face plates respectively confronting said second contact elements while being detachably countersunk in said reduced-diameter section, each of said face plates having a thickness substantially corresponding to the difference between the radii of said reduced-diameter section and a pair of adjoining rod sections whereby said face plates have outer surfaces substantially flush with those of said adjoining rod sections, wherein each of said face plates comprises several metallic layers including an inner layer of silver overlain by a protective layer of tin, the latter being overlain by an outer layer of silver positioned for pressure engagement with and retraction from a silver surface of the confronting second contact element.

In an electrical switch comprising a stationary first contact element and a movable second contact element engageable with said first contact element to connect a power line to a load circuit,

• the improvement wherein at least one of said contact elements comprises a metallic support and a wear-resistant conductive armature secured to said support, and
• wherein said armature comprises several metallic layers including an inner layer of silver overlain by a protective layer of tin, the latter being overlain by an outer layer of silver positioned for pressure engagement with and retraction from a silver surface of the opposite contact element.

In an electrical switch comprising a stationary first silver-surfaced contact element and a movable second silver-surfaced contact element engageable with said first contact element to connect a power line to a load circuit,

• the improvement wherein at least one of said contact elements comprises a metallic supporting rod and a wear-resistant conductive part-cylindrical face plate detachably secured to a peripheral surface portion of said rod, part of said face plate being constituted by a stack of several metallic layers including an inner layer of silver, an intermediate protective layer of tin and an outer layer of silver.