Patent GB-403564-A (GB)
Title: Improvements in or relating to transportation systems
IPC: B66B1/16
Filed: 1933-05-17
Abstract: 403,564. Master control of several D.C. motors; actuating controllers. WESTINGHOUSE ELECTRIC & MANUFACTURING CO.,.East Pittsburg, U.S.A.- (Assignees of Stour, N. W.; 6818, Reynolds Street, Pittsburg, U.S.A.) May 17, 1933, No. 14273. Convention date, May 18, 1932. [Class 38 (iii).] A transportation system comprises in combination a plurality of platforms or vehicles disposed on adjacent and/or substantially parallel lines, electric motors for propelling the platforms in the same direction at variable velocities, control means, e.g. sequence drums, face plate rheostats, &c., for starting and for controlling the speed of the motors to accelerate and decelerate the platforms in a predetermined cycle, and a regenerative system for utilizing the energy given up by a decelerating platform to accelerate another platform. As one (highspeed) platform is decelerated to a low speed, another (low-speed) platform is accelerated to the same speed to permit exchange of passengers between the platforms, the fast platform being subsequently accelerated and the slow platform being decelerated to permit loading and unloading of passengers. The system described comprises two platforms 10, 11, the platform 10 being driven by motors M1, MG while the platform 11 is driven by a motor M2. The motors are all compound wound and each pair is connected in series, energy for exciting the shunt-field windings of the motors and for energizing the control equipment being supplied by a direct-current exciter 19 driven by an induction motor 21. The machines MG are mechanically geared to the motors M1 which are connected to power conductors 17, 18 and the machines MG, M2 are so connected that when platform 11 is accelerating the machines MG act as generators furnishing current to the motors M2 while when the platform 11 decelerates the machines M2 act as generators furnishing current to the motors MG. In both cases when the machines are functioning as generators they are driven, entirely in the case of the machine M2 and partly in the case of the machine MG, by the platform to which they are mechanically connected. A continuouslyoperating sequence drum 23 driven, through electrically-operated gear-and-clutch mechanism 28, by a synchronous motor 24 operated by a motor-generator set 47, is provided in each station of the system and controls the speeds of the platforms by progressively varying resistances 25, 26, 27 connected in the shunt-field circuits of the motors M1, MG, M2, the resistances being varied by electrically-operated switches controlled by contact segments on the drum. The generator set 47 includes an A.C. generator 48 driven by a motor 49. By varying the speed of the generator 48, its frequency is varied and hence the speed of all the synchronous motors 24 and the periodicity of the system may be controlled. Another drum 29 also driven by the motor 24 but through clutch-and-gear mechanism 31 automatically controls the motors M1, MG, M2, by means of electrically-operated switches governed by contact-segments on the drum, during the starting of the platforms from rest and makes one complete revolution before being stopped automatically. As the drum 29 begins its rotation it closes (a) through contacts 87, 94, 102, switches 82, 83, 84 which connect the motors M1, MG to the power source (b) through contact 114, a switch 113 which energizes the shunt field windings of the motors MG by connecting them to the conductors P, N energized by the exciter 19 and (c) through drum segment 129, switches 123, 172, 174, 176, 178 which shunt the entire resistance 26. As the drum rotates, switches 41, 42 are closed through contacts 135, 142, successively shunting the resistance 37 to accelerate the motors M1, MG. The motors M1 are next temporarily shunted and the motors MG are connected across the power source in series with the resistance 37 by contact 147 closing switch 146 and contact 87 opening switch 82. The switches 41, 42 are then again closed to shunt the resistance 37 from the motor circuit after which contact 162 closes switch 155 to energize the separatelyexcited field windings on the motors M1 and switches 156, 181-184 are closed to shunt resistance 25. The speed of the motors is still further increased to accelerate the platform 10 by the resistances 25, 26 being inserted step-bystep. When platform 10 has accelerated to full speed, contacts 94, 147 open switches 83, 146 disconnecting motors MG from conductors 17, 18. As the drum nears the completion of its revolution segment 186 engages contact 185 closing switch 99 to connect motors M2 in parallel with machines MG. The motor connections are thus established for normal operation of both platforms 10, 11 and the drum 23 is now started by closing a switch 204 which causes energization of the clutch 28 which connects the shaft of the drum 23 to the shaft of the motor 24. At the beginning of the rotation of drum 23 the resistances 25, 26 are connected in the circuits of the motors M1, MG but resistance 27 is shunted out of the circuit of the motors M1 to the conductors P, N. As drum 23 advances resistances 25, 26 are shunted step-by-step thereby decreasing the speed of the motors M1 and increasing the of the motor M2 since switches 213, 214 are both closed by contacts 215, 218. Also switch 113 is closed by contact 223 to connect shuntfield windings of motors MG to conductors P, N. A holding circuit was previously established during the rotation of drum 29 for the switch 155 which connects the shunt-field windings voltage of the machines MG, which function as generators supplying current to the motors M2. Accordingly the platform 10 is decelerated and transfer platform 11 is accelerated. The two platforms run at the same speed for a definite time to permit transfer of passengers, after which as the drum 23 advances the resistances 25,26 are inserted step-by-step so that the slow platform 11 is decelerated and the fast platform 10 accelerated. During this period the machines M2 act as generators supplying current to the machines MG which help to accelerate platform 11. As the drum approaches the end of its cycle switches 44, 248 are closed by contacts 249, 255 and platform 11 is stopped or is moved at a very slow speed to permit unloading and loading of passengers. Emergency stopping of both platforms is effected by throwing switch 35 to the " stop " position thereby actuating drum-switch 32 to its " stop " position. Full field-strength is then applied to the machines MG, M2 by the subsequent closing of the switches 113, 123, 214 thereby ensuring that the machines will function as generators and quickly stop the platforms by dynamic braking, the stored energy of the platforms being dissipated through the resistances 37, 38. The conductor E + and the contact segments 102, 151, 185 on the drum 29 are de-energized, thus causing the switches 84, 91, 99 to be opened thereby disconnecting the motors M1 from the power source and interrupting the connections between the motors M1, M2. Switches 261, 248 are closed to establish dynamic braking circuits for the motor M2, MG respectively. The resistances 37, 38 are connected in the circuits of the motors MG, M2 in order to reduce the current flowing through the motors at the beginning of the dynamic braking action and are shunted step-by-step by switches 41, 42 and 43, 44 controlled respectively by current-limit relays 45 and 46.