Patent GB-190602065-A (GB)
Title: Improvements in and relating to Electric Controllers.
Filed: 1906-01-26
Granted: 1907-01-17
Abstract: 2065. British Thomson-Houston Co., [General Electric Co.]. Jan. 26: Switches.-Relates to switches for controlling motors, particularly three-phase induction motors supplied from a single-phase source. The switch has an intermediate 'off' position, from which it is first moved to the starting position, and is then thrown to the running position, in which it is locked by a no-voltage magnet. Means are also provided for changing the bias of the operating- spring: In the starting position, the fields are connected in Y arrangement with a resistancereactance device for producing a displaced phase at the third terminal. In the running position, the fields are in # connexion with the phase-displacing device cut out, and with one field in parallel with the other two, which are in series. A three-armed lever operated by a handle 2<1>, Fig. 1, has contacts 7; 7<1>, 7<11> ; 8, 8<1>, 8<11>; 9, 9<1>, 9<11> on the underside; each trio being in electric connexion with each other but otherwise insulated. A spring 19, embracing the lever pivot and also fixed studs 20 on the switchboard and lever respectively holds the arm in 'off' position with its outer contacts normally on the shaded non-conducting segments and with its inner contacts on conducting segments 10, 11, 12. The arm is prevented from being thrown at once to running position by a hook 23 on a catch 22, which engages a pin 21 on the lever arm 5. The catch is attached to the armature 24 of a no-voltage magnet 25, and slides vertically with it. Throwing the switch to starting position causes the arm 5 of the lever to raise the armature and catch, until a piece 27 on the armature spindle bridges contacts 28, 29 and energizes the magnet 25, which then holds the armature and catch out of the way. The lever can then be moved right over to running position. In the diagram of connexions shown in Fig. 4, the points 1<a>, 3<a>, 5<a> are connected to the stud 13, segment 10, and stud 13<1> respectively, all of which are directly connected in starting position, so that they form the neutral point. In the starting position, the current passes from the line L to the segment 12, branches at the studs 17, 17<1>, part passing from the stud 17<1> through the reactance E to the winding B and the neutral point 5<a>. The other part from the stud 17 passes through the winding A to the neutral point 1<a>, thence from 3<a> through the winding C to studs 16, 15 and segment 11, and back to the line L<1>. In the running position, from the segment 12 part of the current passes through the studs 18, 17, winding A, stud 16', arm 5, and the segment 11, and to the line L<1>. The winding A is thus in parallel with the other windings, which receive, in series, the current that passes from the stud 18<1> to the conductor 39, winding B, stud 14<1>, segment 10, winding C, stud 16, arm 5, &c. The lever is locked in the running position by a hooked lever 30 pivoted at 31 and provided with a heel which is pressed by a spring 33 so that the hook. engages a stud 32 on the arm 4 of the lever. When the no-voltage magnet releases its armature, the latter drops,.and a collar on its spindle 26<1> trips the lever 30, releasing the stud 32. Fig. 7 shows a modified form nf the no-voltage mechanism for insuring that the switch is first thrown into the starting position. In this modification, it is an essential feature that the act of throwing the switch first into the starting position alters the bias of the arm to the running position. A rotatable collar 21<a> is pivoted under the switch arms, and a stud 22<a> on one of its lugs prevents the rotation of the switch arms towards the right, into the running position, before being first thrown to the starting position. The collar is prevented from rotating by a toggle composed of links 26<a>, 28<a>, the latter being pivoted to a fixed point 29<a> and also to a point 34<a> on the armature spindle of the novoltage magnet. The latter is itself pivoted so as rotate about a fixed point 31<a>. A spring 24<a> surrounds the common pivot of the collar 21<a> and switch lever, and its ends embrace studs 23<a>, 25<a> on the collar and the switch arm 5 respectively. Rotation of the switch lever raises the armature 24, energizing the magnet 25, breaks the toggle, and rotates the collar to the right. The stop 22<a> is then moved out of the path of the arm 6, and the whole switch lever, when the handle is released, rotates under the influence of the spring 24<a> to the running position. Failure of voltage enables the spring 35<a> to draw down the armature 24, throwing the switch to the 'off' position, and locking it against rotation to the running position by means of the toggle;