GB901102A - Improvements in switchgear operating mechanism - Google Patents

Abstract

901,102. Automatic circuit-breakers; switches held set and freed mechanically. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. Feb. 2, 1961 [April 28, 1960], No. 14994/60. Class 38 (5). A circuit-breaker spring-operated closing mechanism comprises a handle pivoted to swing in a vertical plane for charging a spring and for releasing same at a predetermined point in a downstroke of the handle to close the breaker, and a control device normally preventing slow manual closing, but manuallyoperable to prevent the release of the spring in the downstroke and allowing slow closing under manual control in an immediately following upstroke. The mechanism is shown in the fully-open condition in Fig. 2A, and to close the contacts, the handle 16 is lifted clockwise about its pivot 17 to overset a toggle 20, 25, the upper point 32 of which remains stationary, whilst its lower point 22 is lowered. The handle is then moved counter-clockwise and the overset toggle transmits the movement to a lever 33 pivoted at 34 to compress the closing spring 6. At the same time a toggle 39, 40 between lever 33 and a lever 41 connected to the contacts (not shown) is also overset. The mid-point 44 of this toggle is connected by a linkage 49 ... 52 to a roller 54 which becomes latched by a member 46. When the spring is fully stressed, a lug 73 on the handle engages a pin 72 on the toggle link 20 and further movement of the handle breaks toggle 20, 25, thereby allowing lever 33 to move counter-clockwise under the action of spring 6, thereby closing the contacts via the toggle 39, 40 and lever 41. The mid-point 44 of this toggle rides over a spring-loaded stop 57 and engages a surface 57a thereon to resist opening movement of the contacts. The manual control device for allowing slow closing comprises a lever 60 pivoted at 63 and having an arm 67 engaged by a spring 68 which normally biases the lever clockwise). The lever 60 also has two pawls 61, 62 co-operating respectively with notches 64, 65 in a boss 66 on the handle 16. When the handle is being moved clockwise to set toggle 20, 25, the pawl 62 engages notch 65 and pawl 61 is moved away from the notch 64, to allow such movement of the handle. During the charging stroke of the handle, movement of the lever 33 removes the spring pressure from lever 60 which tilts counter-clockwise by gravity to remove pawl 62 from the path of notch 65 to allow the full downward movement of handle 16 to occur. However, the lever 60 may be pressed clockwise manually during the down stroke of the handle 16, so that movement of the latter is stopped by pawl 62 and notch 65, which stoppage occurs before the lug 73 trips the toggle to free the closing spring. Thus the handle can now be raised slowly to allow the spring 6 to close the contacts slowly. If the contacts do not close properly, the latch member 46 is tripped by a pin 85 on a lever frictionally engaging the lever 41. The member 46 is normally tripped by manual or solenoid-operated means.