Patent GB-190224455-A (GB)
Title: Improvements in Controlling Devices for Electric Motors Applicable to the Motors of Elevators and the like.
Filed: 1902-11-07
Granted: 1903-03-19
Abstract: 24,455. Waygood & Otis, [Otis Elevator Co.]. Nov. 7. Motors, controlling.-Relates to controlling-devices for electric motors, specially applicable to the control of electric lifts, for stopping the car at a given level with varying loads whether ascending or descending. As the car approaches the given level, a variable resistance is introduced in series with the armature to decrease its speed, if the car is ascending and the armature is being used as a motor, or to increase its speed, if descending and used as a dynamo. A resistance is then thrown in parallel with the armature, and a circuit containing a magnet is completed across the armature terminals. The magnet controls the amount of resistance in shunt, and varies the series resistance, and its operation depends on the potential of the armature after the series resistance is first included. The armature circuit is shown in heavy lines in the diagram, Fig. 1, extending from the positive side of the potential switch S by the wire 24 to the lower brush 19 of the reversing-switch A, then through one side of the switch, the armature B, and the opposite side of the switch to the point 42, then through the starting-resistance C, the series field winding D, electromagnet L, and auxiliary armature resistance E to the contacts 25 controlled by the electromagnet J, and on by the wire 24 to an overload electromagnet F and the negative side of the switch S. The switch A consists of segments 17, 18 bearing against brushes 19, and on the same shaft are arranged switches G, H, I with long segments 20 and short segments 21 bearing respectively against brushes 22, 23. The switch G is operated at the same time as the switch A to complete a circuit from the point 28 through the brushes 22, 23, wire 29, and magnet J to the negative main, thus closing the contacts 25 and completing the armature circuit. A shunt circuit is also completed from the point 2 through an electromagnet K and the wire 30 to the point 31, and then through the resistance 50<a> to the armature circuit at the point 32. The magnet K is momentarily energized, and, as the contacts 33 close, a circuit containing the electromagnet X is completed across the armature brushes. The electromagnet X is completed across the armature brushes. The electromagnet X controls a shunt circuit to the armature containing a resistance R and an extra field winding B<1>. The switch H is operated immediately after the switch G to complete a circuit from the point 34 through the lower brush 22, brush 23, and wire 30, thus short-circuiting the magnet K. A brake magnet Z is controlled by the switch G, and is included in a circuit from the point 35 to the magnet J, a resistance 37 being in the circuit. A shunt across the resistance contains the contacts 38 of the electromagnet Z in the armature circuit. The resistance is adjusted so that the magnet Z is unable to remove the brake when the contacts 38 are open and the armature circuit is incomplete. When the motor reaches its normal speed, the magnet L is short-circuited and the resistance 37 is placed in the brake circuit, but the brake remains lifted. The switch I is next operated to close a circuit from the point 39 through the wire 40, solenoid P, and wire 41. The solenoid increases in power as the potential of the armature rises, and it operates by steps the contacts 3, 4, 5, 6, which are provided with springs of different strengths, or are placed at different distances from the solenoid, so as to be operated one after the other to cut out the resistance C graduaily through the armature circuit, the contact 6 cutting out the series field winding D. Electromagnets Q, Q<1> connected across the line are so wound that, when the magnet J closes the armature circuit, they short-circuit the resistance E step by step to admit gradually the maximum current allowed by the resistance C. Magnets 0, 0<1> in a circuit between the points 47, 32 are so adjusted that, when the potential rises above the normal limit, the contacts 3<a>, 4<a> are opened and resistances are introduced into the circuit of the solenoid P. The wire 29 from the switch G includes one winding 27 of a doubly-wound electromagnet M controlling contacts Y in the circuit of an electromagnet N which holds the switch S closed when energized, and allows it to open when de-energized. From the coil 27 the wire 29 passes to the electromagnet J, then forms an opposite winding M<1> for the magnet M, and passes on to the switch S. Normally the magnet M exerts no force, but, if grounds or leakages occur in any part of the circuits, one of the windings is weakened, and the other is enabled to open the contacts Y in the circuit of the magnet N, which is then de-energized. The overload magnet F, when the current is excessive, similarly opens contacts in the circuit of the magnet N. The operations take place in the reverse order in stopping the motor, and, when the car approaches the given level, contacts 12, 13, 14 in the circuit of the switches I, H, G are successively opened by hand, or automatically by a moving part of the apparatus, to reduce the speed of the motor. When the contact 5 is closed, the back contact 5<a> is opened to throw the resistance 5<b> into the circuit of the magnets Q, Q<1> to prevent them from using too much current. By opening the contact 6<a>, the magnets 0,0<1> are cut out of the circuit. When the contacts 13 are opened, the short-circuit round the magnet K is broken, the contact 33 is closed, and the electromagnet X is brought into operation to put the resistance R in shunt with the armature terminals, either alone, or combined with an extra field winding T to slow down the armature. The magnet X, being placed across the brushes of the armature, varies in strength as the speed of the armature varies, and it is arranged to short-circuit the resistance R gradually according to the load by operating the contacts 7, 7<a>, 7<b>, 7<c>. The back contacts 8<a>, 8<b> are opened as the contacts 7<a>, 7<b> are closed, the circuits of the magnets Q, Q' are thus broken, and the contact 2<a>, 1<a> open and introduce part, or the whole, of the resistance E in series into the armature circuit. With a descending load, the armature is driven as a generator, the resistance C, when introduced, tends to increase the speed of the armature, and the magnet X then closes sufficient contacts to increase the resistance E sufficiently to slow down the armature. The contacts 14, when broken, break the circuit of the magnet J, and the contacts 25 open to break the armature circuit and stop the motor. The diagram, Fig. 2, shows automatic means for making and breaking the motor circuits. The circuits to the switches G, H, I are controlled by a stopmotion switch W consisting of an insulated disc with concentric segmental contacts over which radial contacts a, b move. The central segments d are electrically connected to each other and to the wire 151. The wires c', f<1> connect the segments c, f respectively to the switch H ; the wires g', h<1> connect the segments g, h respectively to the switch I, and the wires i<1>, j<1> connect the segments i,j respectively to the switch G. The switch W is shown with the car in mid position. To start the car, the switches A, G, H, I are moved, say, to the right, and the armature circuit is closed as before. When the switch G joins the brushes 22, 23, a circuit is completed from the point 50 by the wire 51 through contacts d, a, i to the brush 22 of the switch G, through the switch and by the wire 51<a> to the winding 27 of the magnet M, and to the point 53 at which the circuit branches, one branch passing through the wire 52 to the negative main, while the other passes by the wire 54 to the magnet J which closes the armature circuit. When the switch H is closed, the current passes from the contacts d through the contacts a, e, wire e<1>, and brush 22 to the magnet K and on to the negative main. By closing the switch I, a circuit is completed from the switch W by the wires g<1>, 55 to the solenoid P, which cuts out the resistance C and series field winding D as the speed of the motor increases. To stop the car, the contacts a, b are moved automatically to the positions 1, 2, 3, to cut out the solenoid P, then to energize the magnets K, X, Q, Q<1>, and finally to cut out the magnet J which breaks the armature circuit. In the arrangement shown in Fig. 3, the motor B is controlled from the switch C', which may be on the car, or at a distance, and is connected to the controlling-circuits through the switch W'. Two solenoids P', P' are used to control the armature resistance C, and the magnets U, V control the reversing-switch A'. The car is stopped at the limits of its travel by means of the switch W<1>. The positive main is led to the switch A', which consists of contacts k, l, m, n, so arranged that, by raising the core p of the magnet V, the contacts m are closed, and the core 0 of the magnet U is drawn down, closing the contacts l, the contacts k, n being open. The armature circuit is thus completed through the wire 65 and the potential switch S' to the negative main. The contacts 68 of the switch W<1> are connected to the magnets U, V ; the contacts 69, 69<a> are connected to the inner contacts s, s<1> of the switch C<1>. The outer contacts of the pairs 70, 70<a> are connected to each other ; the inner ones are connected to each side of the switch A' ; the outer contacts of the pairs 71, 71<a> are connected to each other, and the inner ones to the outer contacts s, s<1> of the switch C'. To start the motor, the arm q of the switch C' is moved, say, to the left to the position 2<b> ; a circuit is then closed from the point 66 on the positive main through the magnet V, contact b<1> of the switch W', wire 72, and switch C' to the negative main. The magnet V closes the reversing-switch, and completes the armature and field circuits of the motor. By moving the arm q to the pos