Patent GB-668243-A (GB)
Title: Improvements in or relating to high power electric circuit-breakers
IPC: H01H3/30
Filed: 1950-02-20
Abstract: 668,243. Automatic circuit-breakers. NAAMLOOZE VENNOOTSCHAP FABRIEK VAN ELECTRISCHE APPARATEN VOORHEEN F. HAZEMEIJER & CO. Feb. 20, 1950. [Feb. 25, 1949] No. 4331/50. Class 38 (v). The "trajectory-force" diagram A of a source of energy e.g. a spring for closing a circuitbreaker is adapted to the diagram B required by the contacts, by means of an angled guidepiece or equivalent guide-system. As shown at a in diagram A the initial energy of a spring when released, is high and falls off gradually towards the quantity b, whereas as shown in the diagram B, initially the energy is required to increase slowly, then rapidly and finally less rapidly. The spring (not shown) pulls downwardly on a rod 1 pivoted at 2 to a lever 3 having a thrust rod 6 pivoted thereto at 5. The lower slotted end of rod 6 engages a pin 7, which carries a roller 8 and is fixed on a rod 10 connected through links 12,13 to the contactcarrying rod 16. The roller, in the " open " position shown, engages a flat surface 9a on a guide piece 9 and as the rod 1 is pulled down, the roller moves down the surface 9a causing a slow movement of rod 10, to the right until the roller moves on to the segmental part 9b of guide 9, the rod 10 then being moved rapidly to the "closed" position. The part 9a preferably makes an angle of nearly 90 degrees with the axis of rod 6 and with the chord of the segment 9b. In a modification, Fig. 4, the guide surfaces 9a, 9b are formed on a member 20 pivoted at 21, and connected at 22 to one link 23 of an elbow lever 23, 24 having a fixed pivot 26. The hinge 25 of the lever 23, 24 normally bears against a D-shaped abutment 28 so that the sideways force exerted on the member 20 by the roller as it passes along the guide surfaces can produce no movement of member 20. The mechanism is retained in the "on" position by engagement of the roller 8 in a recess 32 in a hook-shaped member 29 also pivoted at 21 and urged counter-clockwise by a spring 35, this latching permitting the rod 6 to be returned to its normal position to re-strain the spring. If the abutment 28 is now rotated so as to free the hinge 25, the member 20 moves to the left, and the roller escapes from the recess 32 and then moves upwardly to the initial position so opening the contacts. The member 20 is immediately pulled to the right by a spring 36 and the elbow lever 23, 24 is reset, the part 24 having an abutment 33 which holds the abutment 28 in its rotated position until the parts restore. The abutment 28 may also be rotated to produce release while the rod 6 is still in its lower position, thus providing a "loose handle" property. In a further modification, Figs. 7a, 7b (not shown), the guide piece rocks about a pivot on the member 20 under the action of the roller so as to produce the desired effect, and in a further modification, Fig. 8 (not shown), the guide surfaces are again formed on the member 20 which is, however, mounted to the right of the roller. In Fig. 9, the guide surfaces 909 are formed on a member 920 pivoted to the rod 906 at 50 and to a member 52 at 51. The member 51 is pivoted at 53 and connected at 54 to an elbow lever 923, 924, so that the member 920 normally pivots about point 51, the co-operating roller 55 being slidable in a slot 56. In a further modification, Fig. 10 (not shown), the guide surfaces co-operate with a roller movable in the slot 56, and are formed on the rod 906, which also co-operates with a roller on a further member connected to the elbow-lever.