Patent GB-746461-A (GB)
Title: Improved control system for an engine-electric locomotive
IPC: B60L15/20
Filed: 1954-08-25
Abstract: 746,461. Control of D.C. motors; controllers. GENERAL MOTORS CORPORATION. Aug. 25, 1954 [Oct. 29, 1953], No. 24758/54. Class 38(3) A locomotive has a compression-ignition engine E coupled to a main generator G which supplies power to traction motors M1-M4 having field winding F1-F4, each connected to a pair of contacts 8 engageable with fixed contacts 4. The contacts 8 are mounted on a rotatable shaft 10 so that the field windings are reversed by turning the shaft through a predetermined angle by means of a rack 14 on a piston rod 26 of a servomotor 16. When a switch SW is in the "forward" position, the solenoid of a valve FOR is energized, the valve being opened to supply air under pressure to cylinder 18 so moving the piston rod 26 to the right. The cylinder 20 is connected to an exhaust through port 30 which is opened when the valve REV is closed. At the same time a switch FR, which is carried on shaft 10 by an arm L, is closed, so energizing the coil of a time delay relay TDC which opens its contacts to prevent energization of valve RCV and relay RR. Movement of the switch SW to the "reverse" position energizes the coil of the valve REV which opens to supply air under pressure to the cylinder 20 and to move the piston rod 26 to the left. The interlock ER is closed to energize the relay TDC When the switch SW is moved to the neutral position, the coils of valve RCV and relay RR are energized, the closure of the normally-open. contacts of the relay RR effect- /ing energization of the coils of the valves FOR and REV. The valves RCV, FOR, and REV are thus opened and pressure is applied in cylinder 18 or 20, according to the position of the pistons, whilst the other cylinder is exhausted through conduit 33 or 32 and conduits 34 and 30. The piston rod is thus moved to the centre position in which the pressures are equal and the rack 14 moves to disconnect the field windings from the motor circuits. Simultaneously, a cam plate 42 is centred to allow a pin to enter notch 46 so that a, spring-biased arm 48 swings about its pivot point to close switch 60. The relay TDC is thereby energized and the opening of its contacts breaks the circuits to the coils of the relay RR and valve RCV. The coils of the valves FOR and REV are therefore de-energized, the spring 54 maintaining the reverser in the centred position so long as no high-pressure air is supplied to the cylinders of the servomotor. A switch ST can then be closed to connect the generator G to battery BAT for operating the generator as a cranking motor to start the engine. 746,470. Control of several A.C. motors. BRITISH THOMSON-HOUSTON CO., Ltd. Dec. 13, 1954, No. 36039/54. Class 38(3) [Also' in Group XXXV] A variable speed alternator 1 supplies the armature of a synchronous induction motor 2, the field windings 3, 4 of the alternator and motor respectively being supplied with excitation current from a polyphase. source 5 through a transformer 6 and rectifier group 9. The field windings of the, machines are each arranged as described in Specification 647,681 with a first section short-circuited and with a second section along the quadrature axis connected to the rectifier 9. Since the field windings from a a closed low-impedance loop circuit, the' surge voltage, which is normally produced when switch 14 is closed, is damped. Resistors 12 are used for adjusting the starting torque of the motor, and resistors 13 regulate the field current. A partial short-circuit of the motor field winding for starting purposes is afforded by a resistor 15, which also produces an additional damping-effect for the high induced voltages of the motor. Resistor 15 may be of the non-linear type, so providing a low resistance path at high voltages and a higher resistance path at. low voltages. More than one motor can be supplied from the alternator, each being accelerated to synchronism with the machine by closing the appropriate switch, whereupon the motors so interconnected with the alternator will remain in synchronism therewith at the desired speed.