Patent GB-633035-A (GB)
Title: Improvements in and relating to variable speed electrical power plant such as for vehicle lighting systems
IPC: H02J7/30
Filed: 1947-11-20
Abstract: 633,035. Supply systems depending on variable speed generators. PESTARINI, J. M. Nov. 20, 1947, No. 30804. Convention date, Nov. 20, 1946. [Class 38 (iv)] In a train-lighting or like supply system comprising a reversible and variable speed generator operating in association with a storage battery to supply a load which may include fluorescent lamps, the generator is of the metadyne type and charges the battery, the load being supplied at constant voltage by a constant speed auxiliary set driven by the battery and including also means for providing a higher voltage suitable for starting lamps. The metadyne machine has secondary variator excitation responsive to battery voltage, whereby, irrespective of the speed of the machine, charging current is automatically reduced to zero when the battery is in fully charged condition. In the train-lighting system shown in Fig. 1 an axle-driven metadyne 2, supplies in conjunction with a battery 1 and motor generator set 3-5 a load comprising incandescent lamps 11 and fluorescent lamps 12, the last being associated with switches 13 whereby the lamps may be connected either to the constant voltage bus-bars 33, 34 for normal running, or to a higher voltage starting bus-bar which is connected to bus-bar 34 through the generator 5 (a metadyne) of the motor generator set. Motor 3 has an unsaturated field so as to drive the set at constant speed irrespective of the battery voltage, whereby generator 4, which is a level compounded machine, supplies constant voltage to the bus-bars 33, 34. Metadyne 2 has a variator winding 19 permanently connected to the constant voltage bus-bar and providing secondary axis excitation irrespective of the speed of that machine, whilst further windings 17, 18 assisting and opposing, respectively, the winding 19 and energized, respectively, from the constant voltage bus-bars and the battery, so as to provide a resultant excitation dependent upon the difference between the bus-bar voltage and the battery voltage, are switched in by a relay 14-16, 20, 21 when the machine 2 is running above a predetermined speed. When the machine 2 is stopped or running slowly, relay contact 14 short-circuits the secondary circuit of the machine through a winding 21 of the relay and opens the battery-metadyne circuit. Contacts 15, 16 are also open. With increase in vehicle speed winding 21 becomes sufficiently energized to change over contacts 14 and close contacts 15, 16, thereby completing the batterymetadyne circuit and connecting the charging- control-windings in circuit. Upon fall of speed, the increasing primary circuit current of the metadyne causes a further winding 20 of the relay to restore the initial connections. In modified arrangements the winding 20 is a reverse-current winding in series with the battery; or the contacts 14-16 may be centrifugally operated by the metadyne speed. Instead of supplying the entire voltage across the constant voltage bus-bars, the machine 4 may be in the form of a reversible booster supplying these bus-bars in series with the battery, as shown in Fig. 2, the voltage of machine 4 being controlled by a field winding 22 which is energized in accordance with the voltage difference between the battery and a shunt generator providing a constant reference voltage. The main machine 2 may have a primary variator winding 27 to reduce primary current and thus copper losses. In further arrangements, Figs. 3-6 (not shown), the machines 3, 4 of Fig. 1, or any two of the machines 3, 4, 6 of Fig. 2, are replaced by a single metadyne machine combining the functions of the two replaced machines. Specification 633,036 is referred to.