Patent GB-490721-A (GB)
Title: Improvements in or relating to electric quick-acting switches with overload release,particularly socket automatic devices
IPC: H01H71/58
Filed: 1937-09-11
Abstract: 490,721. Electrically-released switches. SIEMENS-SCHUCKERTWERKE AKT.-GES. Sept. 11, 1937, Nos. 24782, 24783, 24784, 24785, 24786, 24787, 24788, and 24789. Convention dates, Sept. 11, 1936, Sept. 21, 1936, Sept. 24, 1936, Oct. 1, 1936, July 16, 1937, July 16, 1937, Sept. 10, 1937, and Sept. 10, 1937. [Class 38 (v)] Springs, arrangement of ; arcrupturing devices.-A small quickacting switch with overload release for domestic or industrial use, comprises two latches, one of which is disengaged when automatic release occurs while the other causes the operating handle to remain in position after switching-on, and a contact-pressure producing spring-system is so arranged that it maintains the pressure only until the instant of automatic release, whereupon the switch is opened by a switch-off spring without the contact pressure spring acting on the contacts during the opening movement so as to oppose said movement. In Fig. 1, the pressure-spring 6 is pivoted at 7 and carries a pawl 11 engaging a pin 12 on the pivoted contact-arm 9. The free end of 6 is pivoted at 5 to a toggle comprising the link 4 and handle 1. When the pawl is deflected on overload, the arm 9 is moved off at once by the spring 10, the spring 6 being rendered wholly inoperative. Fig. 3 shows the contactcarrying rod 9 retained set, against the opening- spring 10, by means of the arm 21 engaging a pawl 11 which in turn is retained by a lever 16 having a pin-and-slot connection 17, 18 with one link 4 of an overset toggle 4, 14, the link 14 bearing on a stop 25 and carrying a pin 15 engageable by the handle 1. The pressure-spring 6 acts through levers 16, 21 and pawl 11, but when the latter is deflected is rendered inoperative. Opening by the spring 10 occurs, and spring 6 then acts to break the toggle 4, 14. The handle 1 can also be rotated anticlockwise to open the switch, which occurs rapidly due to the lost motion at 15. The above construction is shown in Fig. 6 applied to a bimetal-strip release 34 and trip'coil 31 acting on the pawl 11. The coil and pawl lie between two metal plates as 30 on the outer side of which the mechanism is arranged. An insulating wall. separates the coil 31 into two halves, the inner ends of which are respectively connected to the fixed contacts 8, whereas the movable rod 9 and spring 10 are located in a bore 38 in the insulating wall. The insulating base 36 is formed with a chamber 37 containing the contacts and blow-out poles 40 and the latter together with the mechanism and release elements may be applied as a unit to the base. Fig. 9 shows a preferred arrangement in which in addition to switch chamber 37 recesses 43 44 are provided for the poles 40 and metal grids 45 leading to hollow spaces 46 are provided in the arc-vicinity. Further substances such as vulcanized fibre nitrocellulose or boric acid may be arranged in grid-form in chamber 37 so as to yield gases under arc-action. The blow-out coil halves may alternatively be located in the arc-vicinity, Figs. 13, 14 (not shown). Fig. 15 shows a modification in which the pawl 107 retaining the arm 106 carrying the contact-rod 101 is carried on the pressure-spring 110. When the pawl is deflected it is necessary, for reclosing, first to rotate handle 114 to the left to break toggle 108, 113, so that 106 re-engages the pawl, and then to restore the toggle to the overset position shown, with 108 resting against pivot 116, during which movements the pivot 117 is guided in slot 119. The movable contact may, in two other forms, Figs. 18, 19 (not shown), be connected to a toggle system having one end retained by the trip pawl and the other end mounted on a fixed pivot and being driven from the handle-toggle system through the pressure-spring. Where the pawl constitutes a magnet-armature, its latching- surface is preferably formed by hard steel plates secured to the softer material of the armature, Fig. 20 (not shown). Fig. 21 shows an arrangement which avoids the need for a powerful contact-pressure spring 315, by removing the spring from between the handle 310 and contact-arm 303. The latter is retained by a toggle 306, 307 and a lever 308 which is pivoted at 309 and engages a pawl 311 which is pivoted at 312 to a lever 313 on which the spring 315 presses. A throw-off spring 305 and trip coil 316 are provided. In a modification of this form, Fig. 22 (not shown), the movable contact is arranged to have a straight-line movement and the lever 308 has a pivot on lever 313 instead of at 309. In Fig. 23, the movable contact 303 co-operates with a contact 302, which is also movable, and has a pressurespring 315 and an extension 333 beyond its pivot serving as a second armature of the trip coil 316. On slight overloads the contact 303 alone may be tripped, the contact 302 being movable only with heavy overloads. Alternatively both contacts may be movable in both conditions, the spring 315 being rendered inoperative in both cases. If desired, separate magnets may be provided for the two armatures 311, 333, or the release on light overloads may be effected by a thermal member. The Specification refers also to a contact-lever comprising two parts pivoted for collective movement on small overloads, one end being acted upon when a short-circuit occurs so as to have an additional movement imparted to it.