Patent GB-190615835-A (GB)
Title: Improvements in Motor Operated Electric Switches.
Filed: 1906-07-12
Granted: 1907-09-12
Abstract: 15,835. British Thomson-Houston Co., [General Electric Co.]. July 12. Switches.-Large switches are closed by a spring previously wound up by an electric motor, while the parts are temporarily' held against movement by an abutment having the form of a toggle, which is tripped to allow the closing' movement to take place. The spring works by straightening a second toggle and compressing a weaker spring in which power is stored for reopening. To reopen, the second toggle is tripped, at will or under an overload, the same trip coil and striker being employed as served to release the first-mentioned toggle. Means are provided for winding up the spring by hand if the motor becomes inoperative, the speed of opening and closing being unaltered. Fig. 5 shows the toggle abutment 55 holding a crank 37 on a rock-shaft 34, against the effort of the previously - compressed spring 89 to straighten out toggle-levers 50, 44. The shaft 34 is connected by means of an arm 36, Fig. 2, through a rod 26 of adjustable length, to the switch arm 8, cramping- levers 9, 10, and contact-brush 4. The contactbrushes for the respective phases are separated by shields 7, and are worked through separate connecting parts. Fig. 2 shows the switch in its closed position, after the toggle 55, Fig. 5, has been tripped and the toggle 50, 44 straightened by the sudden expansion of the spring 89. The tripping is performed by the rise of a lever 61, which is actuated either electro-magnetically by the core of a coil 66, or manually by a rod and handle 75, Fig. 2. The tripping-lever is arranged to fall back immediately after its upward movement, and, if caused to rise again, trips the operating-toggle and allows the switch to open, partly under the action of a spring 38 which was compressed by the closing movement, and partly under its own weight, the parts assuming the positions shown iii Fig. 4. After the switch has thus opened, the electric motor for winding up the spring 89 comes into action automatically. The arrangement of the controlling - circuit and subsidiary switches for effecting this is shown in Fig. 7, in the state that the parts assume with the main switches 4 closed. Leads 100, 101 of the control circuit are connected through a two-way hand-switch 104, 105, provided. with signal lamps 106, 107 to show which side has been closed and thus the state of the main switch. To open, the two-way switch is closed on the side 105, sending a current through the trip-coil 66 by way of the switches 42<a>, 96<a>. The main brush, in moving off, closes a switch 25, sending current to the motor 84<a> by way of a switch 49<a>. The motor begins to run, turning a wheel 78 and a cam 76 in the direction of the arrows. The opening of the main switch has also caused the arm 41 on the sbaft 34 to rock so as to open the switch 42<a> and close 42b, thus de-energizing the trip-coil 66. As the cam 76 rotates, it raises a roller-ended arm 46, which, as shown in Figs. 4 and 5, is provided with a hanging rod 85 to compress the spring 89. Simultaneously, the arm 44, rigidly united to the arm 46, is moved towards the position shown in Fig. 5. The first part of the travel of the motor acts by means of a cam 79 on the wheel 78, to open the switch 96<a> in series with the trip-coil, thus temporarily preventing the latter from being closed by interfering with the two-way switch 104, 105. The same cam 79 also closes a switch 92<a>, forming an additional path for the motor current. Subsequently, the switches 49<a>, 92<a> open in successive order, cutting off current from the motor just after the high part of the cam 76 has passed from under the arm 46, leaving the spring 89 fully wound up. The momentum of the motor carries it on far enough to close the switch 96<a> in the tripcoil circuit. To close the main switch again, the two-way switch is set over to the side 104, exciting the trip-coil, breaking the toggle-abutment 55, and allowing the spring 89 to expand and the toggle 50, 44 to straighten. A slot 47, Fig. 5, for inserting a bar, is provided to allow the switch to be closed by hand power if necessary. Overload magnets 17, adapted to close switches 22, are operative at any time to excite the trip-coil if excess current is flowing, and to open the main switch or prevent its closure.