Patent GB-227098-A (GB)
Title: Improvements in and relating to electric switches
IPC: H01H71/50
Filed: 1924-12-23
Abstract: 227,098. British Thomson-Houston Co., Ltd., (Assignees of Walle, L. S.). Dec. 31, 1923, [Convention date]. Automatic circuit-breakers etc.; electric motor actuation ; switches, actuating. - An electric switch-operating mechanism of the kind including a toggle adapted to be held by electromagnetic means in thrust-transmitting position during and after the closing of the switch, has means responsive to reverse current for rendering the electromagnetic means ineffective. An additional trip free mechanism for maintaining the toggle in .thrust-transmitting position, comprises a second toggle and an overload device for tripping the second toggle. The toggle links 6, 7, Fig. 1, are pivoted respectively to a crosshead 3 on a rod 4 slidable in the bridging-member 1 and to a cross-head 10 slidable on a guide 11. The latter pivot 9 carries a roller 13 engaging a cam 16 .driven by a motor 14 through reduction gearing 15, the cam being formed with a part 20 of constant radius, a lip 21, and an undercut part 22, and being adapted to make a complete revolution to re-set the breaker. The motor circuit is automatically opened when the roller engages the part 20 of the cam, the momentum carrying the cam till its lip 21 engages the roller 13. The toggle 6, 7 is held underset by a, link 23 pivoted to the armature 25 of the magnet 27, the armature being in turn pivoted at 26. The, magnet 27 has a voltage coil 28 and a reserve current winding 29 comprising a bar bent to make a single turn 30 about a laminated core 31 bridging the air gap of the magnet. Release of the armature allows the toggle to collapse and the switch to open. Rotation of the cam to re-close causes the roller 13 to ride over the lip 21 to the part 22 when the links straighten and the armature falls back. In the modification shown in Fig. 2, the link 23 forms with a link 34 a second toggle carrying - roller 35 adapted to be engaged by the plunger 39 of an overload coil 38. Where the cam is rotated at high speed to re-close, means for positively restoring the links 6, 7 are used and comprise a slotted link 43, the slot of which engages a pin 44, and a crank 42 on the camshaft so that rotation of the. latter causes the armature to return and force the roller 13 against the part 22 of the cam. Similar means may be used to restore the links 23, 34, or, alternatively, a spring 46 may be used if the speed of rotation is not too great. Fig. 3 shows a circuit for the breaker which is in series with the reverse current and over-load windings, wheil the voltage winding may be shunted by a switch 49 for manual operation or may be de.-energized. To close the breaker a switch 53 is first closed whereby the switch 54 is operated to close the motor circuit. The circuit of switches 53, 54 is first closed through a switch 52, adapted to be closed when the breaker opens, then as the cam rotates it is completed through contact 50 and segment 51 until the latter separate when the switch 54 opens the motor circuit. The contacts 50, 51 separate. when the roller engages the part 20 of the cam and re-engage when it passes over the lip.