A circuit interrupter, such as a vacuum switch, comprises a pair of relatively movable contacts, at least one of which is a relatively flat disc made of high-cathode drop material, such as molybdenum and having one or more spiral slots extending inwardly from the periphery of the contact filled with solid low-cathode drop material, such as antimony to cause rotation of an arc between said contacts and to facilitate movement of the arc terminal as the arc rotates.
An electrical contact structure of a vacuum interrupter wherein a pair of electrical contacts 2 are provided within a vacuum vessel 1 through a pair of contact rods 14 so that one is in contact with the other or away therefrom. The electrical contact 2 comprises a substantially disk-shaped contact body 2b made of high electric conducting metal portions and metallic pipes having a low electric conductivity, and a plurality of major current flowing sections 22 made of metal having a high electric conductivity, penetrated in the contact body 2b in a manner to be penetrated in the direction of the thickness of the contact body 2b and separated from each other. As an alternative form, the electrical contact 2 may comprise a substantially disk-shaped contact body 2b of ceramic pipes 21 having a low electric conductivity and a plurality of penetrating portions (21a, 21d) wherein each portion (21a, 21d) along the inner and outer periphery of which a chromium oxide film 21b, 21c is formed, is filled with copper to form a plurality of major current flowing portions 22. As a further alternative form, the electrical contact 2 may comprise a substantially disk-shaped contact body 2b of ceramic pipes 21 having a low electric conductivity and a plurality of penetrating portions 21a, 21d and a plurality of major current flowing portions 22a formed by filling copper containing a chromium oxide material of about 0.1% to 0.6% by weight.
An electrical contact assembly includes a contact, a contact support integrally connected to a first surface of the contact, and an insert disposed proximate a second, arc-supporting surface of the contact for stabilizing an electrical arc. In one embodiment of the invention the insert comprises an electrically insulating material inset in the arc-supporting surface and forming a metal-insulator boundary therewith. In another embodiment of the invention, the insert comprises a material having a relatively higher electrical resistivity than the contact, and disposed inside the contact so as to leave an integral metal current path from the arc supporting surface of the contact to the contact support, substantially through the center of the contact.
