Patent GB-657036-A (GB)
Title: Overhead and underground traction power supply systems for high-frequency electrified transport with contactless energy transfer
IPC: B60L5/00
Filed: 1946-03-26
Abstract: 657,036. Electric traction. BABAT, G. I. March 26, 1946, No. 9270. [Class 104 (iii)] In a high-frequency induction system with vehicles receiving current through two coupled oscillatory circuits, one a conducting network along the roads and the other a receiving frame on the vehicle, the conductors are sub-divided into separate insulated lengths l equal to #/2 (the half wave length corresponding to the particular high frequency) and are longitudinally displaced from each other a fraction of their length to obtain a uniform current transmission to the vehicle. The conductors are arranged in overlapping manner and may be at an angle to the line of traffic and may be straight, zig-zag or angular, and the crosssection of the conductors may decrease from the centre to their ends. Fig. 3 shows angular conductor lengths l displaced longitudinally from each other by an amount l/4 and with choke coils L connected to the centre of each length l. The coils may be connected to the ends of the lengths ; a choke coil may be connected to each length or only to one in two or more lengths. The conductor lengths may be installed vertically in deep channels or upstanding barriers at the sides of the road. The choke coils may be placed in wells 12', Fig. 12, along the channels which have insulating covers 12<5>. The conductor lengths are shown at 12<2> and the feed and return lines 12<3>. The conductor lengths 12<2> may consist of concentric tubes supported on ribbed insulators. Radiation losses are reduced by the supply conductors being arranged in a transposed manner. To reduce eddy currents and localize the transverse electric field, the channels for the conductor lengths 2, Fig. 8, are provided with transverse screen wires 3 which are not connected longitudinally. The distance between the screen wires must be less than their distance from the conductor 2. The screen wires may be laid on the surface of the road bed and covered over or placed in grooves which are then filled in, or they may be wound around ceramic or asbestos tubes in which the conductors are placed. The soil may be treated with mineral oil, coal tar, resin soap, and iron sulphate and divided by partitions to reduce eddy currents therein. Large areas may be supplied uniformly by employing moving magnetic fields. As shown in Fig. 14 a zigzag three-phase system is formed of conductors A, B, C supplied from valve generators and having delta-connected inductances 14L at the joins of the zig-zags. The coils may also be connected in star or zig-zag fashion. The use of two travelling fields at an angle of 90 degrees to each other will enable the vehicle frame to absorb the same energy independently of its azimuth. To avoid interference between the two fields, the power supply to the two generators is arranged to work alternately by connecting the generator anodes to the half windings of a single phase transformer ; their frequencies should be sightly different but their amplitude constant. To give increased power to vehicles at turns, the tractive power may be concentrated into lanes by installing at the turning area auxiliary closed circuits inductively coupled to the main circuits, Fig. 21 (not shown). Likewise, on inclines the power may be similarly concentrated. Specifications 615,916, [Group XXXV], and 657,035 are referred to.