Circuit-interrupter grid structure for an oil-break circuit interrupter

A liquid-break type of circuit-breaker including a tank containing an arc-extinguishing liquid, a pair of terminal-bushings extending downwardly within said liquid-containing tank, each carrying an interrupter grid-unit (5), each grid unit (5) including at least three vertically segregated arc-extinguishing liquid chambers (42, 43, 44), means defining a first upper arc-extinguishing liquid chamber (42) particularly adaptable for interrupting high-amperage-value fault currents, said first chamber (42) being completely enclosed except for a lateral relatively-small vent opening (11), said first chamber (42) being partially defined by a lower-disposed valve plate (37) having only a small central opening provided therein, stationary contact means (19) disposed within said first chamber (42) including an elongated off-center finger contact (21A) extending downwardly close to said lateral restricted vent opening (11), a rod-shaped movable contact (7) movable upwardly and downwardly in its closing and opening movements and cooperable with said elongated stationary finger contact (21A) to establish an arc initially wholly within said first arc-extinguishing liquid chamber (42) while blocking said central opening (37) with valve action, means defining a second liquid interrupting chamber (43) disposed below said first chamber (42) and having said valve plate (37) forming its upper end, said second chamber (43) having at least two lateral vent openings (12, 13) in alignment with said first-mentioned restricted vent opening (11) and having at least one splitter plate (39) therebetween for effecting arc looping therearound into said two lateral vent openings (12, 13), said second chamber (43) being particularly adaptable for interrupting medium-value fault currents, a second valve plate (37) with a relatively-small central opening closing the lower side of said second interrupting chamber (43) with said movable rod contact (7) making valve action therewith, means defining a third interrupting chamber (44) disposed below said second chamber (43) and particularly adaptable for interrupting low-value currents and additionally having at least a pair of lateral vent openings (15, 16) therein also in alignment with the aforesaid vent openings (11, 12, 13), said third chamber (44) being located below said second-mentioned valve plate (37) and having its lower end closed by a third valve plate (49) having only a small central valve opening therein, a splitter plate disposed between the two lateral vent openings (15, 16) of the third interrupting chamber (44) to provide arc looping around the said last-mentioned splitter plate, again the movable contact-rod (7) making valve action with said last-mentioned valve-plate, at least one additional lowermost separate liquid completely-confined interrupting chamber (50, 51) for assisting in the interruption of the low-value-amperage currents having no lateral venting whatsoever, said lower-most additional liquid chamber (50, 51) having its upper and lower boundaries defined by valve-plates (49), and said interrupting unit 5 having a bottom apertured nozzle member (62) with a central orifice opening therein out of which the movable contact rod (7) moves at the end of the opening operation.