Contact structures for vacuum-type circuit interrupters having cantilevered-supported annularly-shaped outer arc-running contact surfaces

Claim 1

An alternating-current electric circuit interrupter of the vacuum-type comprising, in combination: a. a first ring-shaped electrode having a segmented ring-shaped contact-engaging surface; b. a second ring-shaped electrode having a segmented ring-shaped contact-engaging surface; c. an evacuated envelope surrounding said first and second electrodes; d. the two segmented ring-shaped contact-engaging surfaces of said first and second ring-shaped electrodes making abutting contacting engagement in the closed-circuit position of the vacuum-type circuit interrupter; e. the arc during the opening operation of the interrupter being initially established between the separated ring-shaped segmented contact-engaging surfaces; f. a rod-shaped contact-support stem (12, 14) for each segmented electrode having a termination point (12a, 14a) disposed in a plane (Z-Z) spaced axially inwardly from the support plane (YY) of the respective electrode; g. an obliquely-extending spoke (44) for each contact segment (36a) supporting the same rearwardly thereof in the support plane (y-Y); h. each spoke (44) supporting its respective contact segment (36a) at one end thereof (36b) in a generally L-shape; i. the spacing between immediately-adjacent spokes (44) being relatively wide to result in an open, vented contact construction for readily venting rearwardly of ionized products of arcing for a consequent rapid build-up of dielectric strength; j. the spokes for the first and second electrodes being mirrorimages of each other to thereby cooperatively augment the arcrotation movement of the established arc around the ring-shaped contact-engaging surfaces; and, k. the axial distance between the supporting planes (Y-Y) of the first and second electrodes being sufficiently large to prevent substantial radial outward magnetic looping of the arc.