Patent GB-724335-A (GB)
Title: Improvements in and relating to electrical power systems
IPC: B60L50/10
Filed: 1953-04-13
Abstract: 724,335. Transmitting mechanical power; automatic current-control systems. GENERAL ELECTRIC CO. April 13, 1953 [Feb. 18, 1952], No. 10016/53. Class 38 (4). [Also in Group XXXVII] In a traction system, a generator 1 has a separately excited field winding 2 and is connected to a number of traction motors 4. The field winding 2 is energized from an amplidyne 5, both the machines 1 and 5 being driven by a prime mover 7. A control winding 6 of the amplidyne is supplied from lines 8, 9, in series with a resistor 10 across which is developed a variable bucking voltage derived from rectifier 20. A magnetic amplifier 11 provides the input voltage for the rectifier 20, and has one control winding 23 energized from a resistance bank 25 in order to establish the desired level of generator current, whilst another control winding 24 of the amplifier is energized in accordance with the generator current thereby to maintain that current at the desired level. The control winding 23 is connected in series with an amplifier control winding 22 which acts additively with the winding 24, and the winding 23 is shunted across the resistance bank 25 which is regulated by a controller 45 so that operation of the controller progressively shortcircuits sections of the resistance bank to increase the voltage applied to winding 23 and decrease that applied to the winding 22. Thus, when the controller contact 37 is closed, the winding 23 is short-circuited and the voltage across lines 8 and 9 is applied to winding 22. The reactor 12 is highly saturated so a low voltage appears across points 18 and 21 and a high voltage across points 19 and 21. The input voltage to the rectifier 20 is at a correspondingly high level with variations of the voltage applied to the winding 24 producing variations in the rectifier output about that level. A high value of bucking voltage is applied to resistor 10, the generator field winding 2 having low excitation. With all the contacts 37-43 open in the last position of the controller 45, maximum voltage appears across the winding 23 and the voltage applied to the rectifier 20 is at a minimum. In order to provide an additional notchless control of tractive effort, a continuously variable potentiometer 51 is connected in circuit. A hump shunting controller 54 adjusts the potentiometer 51 and a switch 52, so that, when the controller is in the position shown and a reversing controller 57 is in an operative position, a relay 35 is energized and the resistance bank 25 and resistor 36 is connected to line 8 through potentiometer 51 and train wire 55. Advance of the controller 54 smoothly reduces the generator current for any given position of the controller 45. The train wire 55 enables operation of the controller 54 in a leading vehicle to provide regulation throughout the train. Since the controller 57 is in the leading vehicle, alteration of the potentiometer 51 in a trailing vehicle does not disturb the setting by the driver. The handle of the controller 45 is linked with the regulator of the prime mover 7 so as to provide simultaneous regulation of the speed and excitation of the generator 1.