Patent GB-190324800-A (GB)
Title: Improvements in Electric Braking Systems
Filed: 1903-11-14
Granted: 1904-09-15
Abstract: 24,800. British Thomson-Houston Co., [General Electric Co.]. Nov. 14. Motors, controlling. - In electric braking - systems applicable to railway cars and other purposes, means are provided for allowing the operator to convert the repuls i o n propelling- motors into induction braking-generators when the machines are working at a speed greater than that of synchronism. Alternating current is supplied from a source A, through mains and controllers B, C, to a repulsion motor M, which comprises a primary member P having a winding W, a secondary member S having a winding W', and three-phase collecting-rings c, d, e connected to the winding W<1>. The brushes F, G bearing upon the co nmutator E, the collecting-rings c, d, e, and the taps f ... r on the winding W are connected to fixed contacts on the controllers, resistances R<1>, R<2>, R<3> being arranged in the collecting-ring circuits to regulate the braking effect. When the controller C is moved towards the left from the 'off' position shown into the position in which the fixed contacts 1 ... 10 lie along the dotted line 1-1, a circuit is completed from one main through the conductors 34, 35, fixed contacts 1, 2, conductor 36, tap f, winding W, tap r, conductor 37, fixed contacts 6, 5, and conductors 38, 39 to the other main, and the armature is short-circuited through the brush F, conductors 40, 41, fixed contacts 10, 9, conductors 42, 43, and brush G. These connections compel the machine to act as a repulsion motor in the starting position, and the further movements of the controller C towards the left give positions of the contacts, indicated by the dotted lines 2-2, 3-3, which compel the machine to run as a motor. Similar running in the opposite direction is obtained by turning the controller C towards the right to act in conjunction with the fixed contacts 11-20. When it is desired to convert the motor into a braking-generator, the controller B is turned towards the left until the fixed contacts 21 ... 33 lie along the dotted line 4-4, and a circuit is thus completed from one main through the conductor 46, fixed contacts 33, 32, conductor 47, tap p, winding W, tip h, conductor 49, fixed contacts 22, 21, and conductor 48 to the other main. The winding W<1> of the secondary member is connected, through the collecting-ring e, conductor 50, resistance R', and conductor 51, to the fixed contact 23, and, similarly, through the collecting-rings d, c and resistances R<2>, R<3>, to the fixed contacts 26, 29 respectively. The fixed contacts 23, 26, 29 are connected together by the controller B, so that the three-phase collecting rings are connected in Y with a resistance in each leg. If the machine now works at a speed greater than that of synchronism, it returns current to the source A by acting as an induction braking-generator. By turning the controller further towards the left until the fixed contacts 21 ... 33 lie along the dotted lines 5-5, 6-6, the corresponding sets of fixed contacts 24, 27, 30 and 25, 28, 31 are respectively connected together, the resistances in the collecting- ring circuits are varied, and, consequently, different braking effects are obtained.