Patent GB-460284-A (GB)
Title: Improvements in or relating to circuit breakers
IPC: H01H71/38
Filed: 1935-04-16
Abstract: 460,284. Automatic circuit-breakers. TRINKL, H. April 16, 1935, No. 11718. Void. Convention date, April 16, 1934. [Class 38 (v)] An automatic circuit-breaker comprises rotary contact members 19, 20 engaging fixed contacts 4 in separate insulating chambers 3, the axis of rotation of the rotary contact members being so arranged that the whole volume of the chambers is used in separating the contacts. In the construction shown, applied to a threephase circuit-breaker with a double break on each phase, the chambers 3 are formed by placing together two insulating shells a, b, each shell being provided with insulating partitions 1, 2 to form the separate chambers. The fixed contacts 4 are mounted on semi-cylindrical walls 6 of the shells, the connections from the fixed contacts to the terminals 15, 16 being made through blow-out coils 21, the coils for each shell being mounted on common magnetic cores 29, 30 provided with flanges or polepieces 31 for each phase. The rotary contacts 19, 20 for each phase are connected together by bridge members mounted on a common spindle 11. The operating mechanism comprises a control spindle 55, Figs. 13 and 14, connected through toggle linkage 64, 65 and 66, 67 to the contact spindle 11. The spindle 55 carries a toothed segment 58 which is rotated to close the circuit, by means of a rack 56 carried by a push-button 57. The lever 64 is rigidly secured to the spindle 55, and the lever 67 to the spindle 11, so that rotation of the spindle 55 moves the toggle linkages to the position shown in Fig. 14 and rotates the spindle 11 to close the circuit. The lever 67 has an arm 71 connected to a spring 73 which is placed in tension on closing the circuit, while another arm 72 of the lever engages a fixed stop 74 in the open position of the switch, Fig. 13. The spindle 55 carries a spring-controlled pawl lever 82 which during the first part of the closing movement engages a projection 85 on an arm 87 of a two-armed lever pivoted at 86, and rotates the lever against the action of a spring 94 until the nose of the arm 87 engages a notch 90 in a spring-controlled pawl 44 pivoted at 47 ; the two-armed lever is then held by the pawl 44 while the pawl lever 82 escapes past the projection 85 as shown in Fig. 14. The switch is retained in the closed position by the overset toggle mechanism until the pawl 44 releases the two-armed lever, whereupon the arm 88 of the latter is drawn to the right by the spring 94 and strikes a sharp blow on the cup-shaped surface 97 of the toggle link 66 to break the toggle and permit the switch to open under the action of the spring 73. The release of the pawl 44 may be effected by electromagnetic means on heavy overload or by thermal means on moderate overloads. The electromagnetic release is effected by an armature 32 which extends across the polepieces 31 of the blow-out coils 21 on the left-hand side of the apparatus, Fig. 6, the armature being carried by a frame 37 pivoted on two pivots 36. The free ends of the side members of the frame are provided with slots 39 engaged by regulating members 40, which permits the air-gap between the armature and polepieces to be adjusted. The armature is normally held away from the polepieces by springs, but, on overload it is attracted to the polepieces, and an adjustable screw 42 carried by the armature acts on an arm 43 carried by the pawl 44 and rotates the latter to -release the arm 87 of the two-armed lever, with consequent opening of the circuit. The armature may also be moved mechanically to open the circuit by a push-button (not shown). The thermal release comprises U- shaped bimetallic members 27 connected in each phase, which are adapted on bending to engage stops 49 carried by metal blades 48 on a spindle 47 carrying a lever 45 adapted to engage the arm 43 on the pawl 44. Adjusting members 51 are provided for regulating the distance between the stops 49 and the ends of the bimetallic members 27. To compensate for ambient temperature variations, the blades 48 may also be bimetallic. The lever 65 is formed with a toothed segment 77 which, in the latter part of the closing movement, slips past a spring arm 79, but if it is attempted to retract the push-button 57 before the switch is completely closed, the lever 65 pivots about the engaged tooth of the sector and the toggle is upset.