Patent GB-190524236-A (GB)
Title: Improvements in and relating to Electric Switches.
Filed: 1905-11-23
Granted: 1906-11-22
Abstract: 24,236. British Thomson-Houston Co., [General Electric Co.]. Nov. 23. Switches.-Relates to mechanism for allowing two switches to open only in a definite order, the first to be restored to its former position when the second is operated, particularly applicable to the starting and running switches of a three-phase induction motor. The bridging-contacts of the oil switch are raised by an arm 24, Fig. 1, pivoted at one end to the movable yoke, and at the other end to a fixed point in the casing. The arm is raised by a toggle 25, 26, which is extensible by means of a lever 28, connected at its outside end to a pivoted actuating-lever 22. To prevent the running switch B, Fig. 2, from being thrown while the starting-switch A is closed-and the current is flowing through the compensator to the motor, a lever 45 is pivoted at 46 midway between them. One of its arms is pressed by a spring 52 against the inside of the toggle member 26<b> of switch B. The other arm is out of the path of movement of the toggle member 26<a> of switch A but contacts with it when the switch A is in full on position. The lever 45 is locked so as to prevent the running switch from being thrown until the starting- switch has been thrown, by means of a latch 47, pivoted to the casing at 48, Fig. 6. The latch has a shoulder 53 that normally locks the lever 45 with the switch B off, but may be tripped by means of its nose 49 which is in the path of movement. of an independent lever on the same pivot 46. This lever is always held by a spring 51 against the .toggle member 26<a> of the switch A. The running switch can be opened only by means of tripping-mechanism, consisting of a plunger 57, Fig. 3, adapted to be drawn up into a solenoids and provided with a projection 58 which knocks up a pivoted arm 59. The arm 59 breaks a toggle consisting of arms 61, 62, pivoted to arm 22 and link 28, respectively, interfering with the positive engagement of the last two members. The link then slides by means of a slot 60 in its end over a projection on the arm 22 as the contacts sink over and open circuit in the oil pots. A modified form of the locking-device for the switch arms is shown in Fig. 9. A member 68 with a head 76<a> slides laterally in eyed lugs on the casing, having at one end a collar 75 which takes against a fixed bearing 69, and at the other a free engagement with a hollow stud-shaped part 74. The latter is also slidable in the other lug and has a collar 73 to limit its movement in the outward direction. A spring 76 presses the collars 73, 75 outwardly. The two parts 68, 74 are constrained to move inwardly or outwardly together b means of a pivoted oscillating link 78 connected to the collar 75, and a connecting-link 77, connected to collar 73. The parts when at rest, in the position shown in full lines so that only the starting-switch can move its member 26<a> against the inclined face of part 74. After this has been done, the square face of head 76<a> is removed from the path of the toggle member 26<b>, freeing it and allowing it to contact with the sloping surface of the head. Passage to the full-on position is prevented by the forcing outwards of the point 80 which stops against member 26<a> until the starting-switch is opened. The running switch can be thrown full on and the point 80 forced right outwards preventing the throwing of the starting-switch.