GB210744A - Improvements in and relating to methods of and apparatus for regulating electric distribution systems - Google Patents

Abstract

210,744. British Thomson-Houston Co., Ltd., (Assignees of Coolidge, W. D.). Jan. 30, 1923, [Convention date]. R÷ntgen-ray and like apparatus.-By means of an electronic discharge, a substantially constant potential is maintained across an X-ray tube 1, Fig. 1, even though the voltage across the supply conductors 7, 8 varies; on a substantially constant current is maintained in the cathode of an X-ray tube 40, Fig. 3, and also through the anode thereof, even though the voltage across the supply 34 varies. In the apparatus shown in Fig. 1, the supply current passes through an impedance 13 and is then shunted through a transformer 17 to the cathode 9 and also through a transformer 4, and synchronously driven rectifier 5 to the terminals of the tube 1. An increase of supply voltage produces a corresponding increase in cathode current, and thereupon a magnified increase in the anode current through the tube, which is operating at saturation current, thereby increasing the potential drop across the impedance 13 to such an extent that the potential across the primary of the transformer 4 only rises very slightly. If a second impedance is inserted between the transformer 4 and the junction of the leads 8, 18, then the potential across the transformer can be maintained constant or even caused to drop when the supply voltage increases. The X-ray tube may be constructed to rectify its own current, whereupon the rectifier 5 can be omitted.. In the apparatus shown in Fig. 3, the tube 1 is replaced by an electron discharge device 32 operating with a low voltage drop, though still at saturation value, and the constant potential difference across the primary of the transformer 4 is utilized to supply through a transformer 43 a constant heating current to the cathode of an X-ray tube 40, whereupon the electron current through the tube 40 due to the transformer 48 remains substantially constant. Both the electrodes of the tubes are preferably made of tungsten.