Patent GB-190426099-A (GB)
Title: Improvements in Electric Motor Controlling Systems.
Inventor: EASTWOOD ARTHUR CLARKE
Filed: 1904-11-30
Granted: 1905-03-30
Abstract: 26,099. Eastwood, A. C. June 10, [date applied for under Patents Act, A.D. 1901]. Motors, controlling.-Series-wound motors are controlled so that, before a reversing-current can be applied to the motor, the current is cut off and the motor is connected so as to act as a generator, and brake itself ; interlocking means are provided for preventing the current-supply and shortcircuiting switches from being simultaneously closed. One arrangement is shown in Fig. 1, in which A is the motor armature, F the field, and C a controller connected as shown to the motor and the regulating-switches S, S', &c. The arrangement of the switches preferred is that described in Specification No. 26,098, A.D. 1904. If the main switch B be closed and the controller arm c' be moved from its 'off' or vertical position to the first position, the main current flows from the positive pole of the switch B, through the coil s<1>, contact c<5>, arm c<7>, and contact c' and back to the negative pole. The switch S<1> then closes, and supplies current to the motor through the resistance R', field F, contact c', arm c<7>, and contact c', armature A, and contact c, arm c<7>, and contact c<4> ; as the motor gains speed, the sections of the resistance R<I> are successively cut out, as described in Specification No. 26,098, A.D. 1904. On moving the arm c<7> off the contact e<5>, the current to the coils is cut off, the switches open, and no current is supplied to the motor. When the arm c<7> reaches the segment c<3>, the motor circuit is closed, but no field is built up until the arm c<7> bridges the segments c', c, c', c<4>, c<3>, when the motor acts as a generator, sending a current through the contact c<1>, arm c<7>, contact c<5>, resistance R, coil s, field F, and contact c' and arm c<7>, thus braking itself and coming to rest. The locking-bar T prevents the switches S, S' from closing together. The switch S may be wound with two coils, one being connected to the contact c<3> and the positive pole of the switch B, the negative terminal of which is connected to one terminal of the switch S, the other coil being connected to the field F and the resistance R. The other end of the resistance is connected to the second terminal of the switch S. With these connections the switch S closes when the arm c<7> reaches the contact c<3> ; one end of the second coil may be connected to the contact c<2> to which the field F is joined, and the other to the contact c<4>, the main, and the resistance R, which is also connected to one terminal of the switch S, the second terminal of which is connected to the field. In this case one of the two coils on the switch S is in shunt with the resistance and field, instead of being in series as before. As shown in Fig. 4, all the devices may be operated by a controller D, and additional switches S<5> &c. are provided for reversing the relative connections of the motor field and armature, and main switches S<9>, S<10>. On moving over the contact d<9> to the studs, the switches S<6>, S<8>, S close, but the coil of the latter is de-energized just before the contact d<3> is connected up. When the switches S<9>, S<10> close, the motor is energized through the switch S<10>, resistance R', field F, switch S<6>, armature A, and switches S<5>, S<9>, and, as the controller is rotated, the motor speeds up and the switches S', S', &c. successively close. On moving the controller to the 'off' position, the switches S<6>, S<5> open and the switches S<5>, S<7> close ; even if the controller be further revolved, the switch S remains closed, as the coil S<11> is energized by the motor ; the closing of the switches S<9>, S'‹, which are supplied by lock bars t, t<1>, is prevented until the motor comes to rest and the switch S opens. To prevent two sets of switches from closing together, locking-devices such as the bars t<2>, t<3> are provided. Fig. 5 shows the system applied to two motors A<1>, A<2> connected in parallel. The connections are the same as in Fig. 4, except that the switch S has but a single coil, and a double-faced controller G<3> is used such that movement of the arm in one direction operates on the contacts on one face for forward driving, and movement in the other direction operates on the other contacts for reverse driving. The switches E, E' enable one motor to be operated without the other. Specification No. 26,096, A.D. 1904, is referred to.