Patent GB-190314079-A (GB)
Title: Improvements in Controlling Systems for Electric Motors.
Filed: 1903-06-24
Granted: 1904-06-16
Abstract: 14,079. British Westinghouse Electric and Manufacturing Co., [Westinghouse Electric and Manufacturing Co.]. June 24. Motors, controlling.-A pair of motors is changed by steps from series to parallel, or vice versÔ, without the use of external resistances. Fig. 2 shows the successive steps. In No. 1, the armatures A, B and fields C, D of the two motors, and the starting-resistance E, are shown in series. Nos. 2, 3, 4, and 5 show the gradual cutting out of the starting-resistances. No. 6 shows the two fields in parallel, the intermediate steps being shown at 5<1>, 5<2>, namely, the field C is first shortcircuited and then cut out entirely, and finally the parallel arrangement is made as shown. No. 7 shows the next arrangement desired, namely, with the two armatures A, B and the field C in parallel, Nos. 6<1>, 6<2>, and 6<3> representing intermediate stages. In No. 6<1>, the field C is short-circuited; in No. 6<2>, the circuit is broken at several points, whereby several arcs form which tend to maintain the circuit relations of the position 6<1>, and in a measure superimpose the connections of that position upon the connections shown in No. 6<3>, in which the armature B is short-circuited. In No. 7<1>, the circuit is again broken at several points, and then re-connected in parallel as shown in No. 8. Any controller capable of making these changes may be used, a form of the usual rotary drum type being illustrated, in which the development of a controller drum agrees with that shown at F in Fig. 5, while the combined reversing and motor cut-out switch is of a well-known type. This method is applicable to more than two motors, used in groups. To enable a motor when disabled to be cut out of circuit without interfering with the operation of the remaining motor, the arrangement shown diagrammatically in Fig. 5 is used. The references A, B, C, D, and E correspond to those in Fig. 2, and the dotted lines 1 to 8 in the development of the drum F to the corresponding numerals in that Figure. The six operative positions of the reversing and cut-out switch G are indicated by the dotted lines II to VII. At the positions II and III, the motor comprising the armature A and the field C is in circuit alone, and is running backwards and forwards respectively, while at the positions IV and V both motors are in circuit running forwards or backwards respectively, and, at the positions VI and VII, the armature B and field D are alone in circuit, running backwards and forwards respectively. In the positions II and III, the fingers 121, 122 connected with the field D, and the fingers 129, 133 connected with the armature B, have no contact engagements, while in the positions VI and VII, the fingers 125, 126 connected with the field C, and the fingers 130, 136 connected with the armature A have no contact engagements. As an illustration, the following are the circuits when the switch G has its contact-fingers in engagement with the contacts on the line III, and the switch F with the fingers on the lines 1 to 8 :-When on the line 1, the circuit is from the trolley 50 to the finger 49, contact 32, 31, finger 48, finger 131, contact 109, finger 130, armature A, finger 136, contact 117, finger 135, finger 45, contacts 23, 24, finger 46, finger 128, contacts 96, 92, finger 126, field C, finger 125, contacts 88, 86, and finger 123 to and through the resistance E to ground. At the positions 2, 3, 4, and 5, the circuits are the same except that the resistance is gradually cut out by means of the grounded contacts 9, 10, 11, and 12. The position at 6 is the same as at 5. At the position 7, the circuit is from the trolley 50 to the finger 49, contacts 34, 33, finger 48, finger 131, contact 109, finger 130, armature A, finger 136, contact 117, finger 135, finger 45, contacts 28, 25, finger 44, finger 127, contacts 94, 92, finger 126, field C, finger 125, contacts 88, 86, finger 123, and finger 40 to grounded contact 12. At the position 8, the circuit is the same as for the position 7, except that the contacts 34, 36 and 26, 27 are in use instead of the contacts 33, 34 and 25, 28. When the switch G is in the position II, the circuits are similar, but the direction of the current through the field C is reversed.