Patent GB-190418203-A (GB)
Title: Improvements in Electric Motor Control Systems
Filed: 1904-08-22
Granted: 1905-08-03
Abstract: 18,203. British Thomson-Houston Co., [General Electric Co.]. Aug. 22. Motors, controlling.-Electric motors for traction purposes are adapted for both alternating, and direct supply by the use of a transformer and a controller which connects portions of the divided fields of the motors in parallel or in series and cuts out resistance from the motor circuit, the lighting, heating, and compression-brake circuits being at the same time similarly adapted to the two different sources and the blow-out coils cut out when the motors are on alternating current. The Figure shows the arrangement for a fourmotor equipment. When the switch D, described in Specification No. 18,202, A.D. 1904, is closed, thereby opening the switch A, the trolley or other source T is connected to the contact e<16> of the commutating-switch E, which adapts the motor to the two sources. The contacts d, d of this switch are next moved to engage with the contact-fingers e<1> to e<18>, and the reversing-switch R is turned to have its movable contacts on the lines f, rf in engagement with the fixed fingers f<1> to f<16>. If the series-parallel controller C is now moved to its first position, a circuit is completed through the trolley T, switch D, contacts e<16>, e<17>, e<8> e<7>, blow-out coil B, contacts c', c', resistance I, contacts f<8>, f<16>, f<5>, f<15>, armatures of the motors M<1>, M<2>, contacts f<13>, f<7>, f<6>, f<14>, lower halves of the fields of the motors M', M', contacts e<14>, e<13>, upper halves of the fields of the motors M', M', contacts c<9>, c<8>, f<4>, f<12>, f<3>, f<9>, armatures of the motors M<4>, M<3>, lower halves of the fields of the motors M<4>, M<3>, contacts e<5>, e', and upper halves of the fields of the motors M<3>. M<4> to earth. The motors are therefore connected in series with the two portions of the field of each motor in series also. Further movement of the controller cuts out the resistance I, and then the motors are connected in parallel and the resistance I reinserted, to be cut out again step-by-step. A circuit is also closed from the switch D through the fuse d<1> and choke-coil d<3>, contacts e<16>, e<17>, lamps L, heating-coils H, and compensator t to earth. If the switch s is closed, a further circuit is completed through the switch D, contacts e<16>, e<17>, switch s, governor g of the auxiliary motor m which drives the air-compressor for the brakes, armature of the motor m, left-hand half of the field of the motor m, contacts e<1>, e<2>, and right-hand half of the field of the motor m to ground. To change the motors to alternating current, the switch A is closed, thereby opening the switch D, and the commutator switch E is moved in the opposite direction to the position a, a. The trolley T is then connected to the primary of the transformer T', and the motors are driven from the transformer secondary. With this arrangement the motors are connected in series with one another with all the resistance in circuit, but the parts of the field are in parallel with each other, the blow-out coils B now being idle. The compensator t has its left-hand terminal connected to the right-band terminal of the secondary winding of the transformer T', and has an intermediate point connected to earth, so that the terminal voltage of the compensator is greater than that of the secondary of the transformer, and, if the compensator t be properly proportioned, the lamps L, which are connected across the terminals of the compensator through the contacts e<17>, e<18>, will be supplied with the same voltage on alternating as on direct current. The same changes are effected in the field connections of the small compressor motor m as those made in the driving-motors of the vehicle.