GB423535A - Improvements relating to control systems for electric discharge apparatus - Google Patents

Abstract

423,535. Phase changing ; converting. SIEMENS - SCHUCKERTWERKE AKT.- GES., Siemensstadt, Berlin. Nov. 24, 1933, Nos. 32892 and 32893. Convention dates, Nov. 24, 1932 and Dec. 8, 1932. [Class 38 (ii)] In a control system for determining the moment of ignition with reference to the anode potential of a gas or vapour filled electric discharge vessel, a coil connected in the grid circuit of the discharge vessel is coupled with a magnetic circuit which is so saturated that variations of the magnetic flux are only produced when the excitation of the magnetic circuit on a change of direction becomes zero or approximately zero, the magnetic circuit being provided with an alternating current excitation of constant phase displacement with respect to the anode potential of the vessel, and with supplementary direct or alternating current excitation. In one form the magnetic circuit 1, Fig. 3, has a winding 2 connected to the alternating current mains, and a winding 3 connected to an adjustable direct current circuit. A third winding 4 on the same core as the windings 2, 3 is connected to the control grid of the discharge vessel 6, a biassing potential being introduced from a source 5 of direct or alternating current in the connection to the winding 4. The current in the winding 2 is given a definite constant phase displacement relatively to the potential of the anode e<a> by connecting an inductance 7 in series with the winding. When a +ve or -ve current from the battery 8 is added to the alternating current excitation of the magnetic circuit the potential impulses produced in the grid circuit are displaced in their time position so that the time of ignition of the discharge vessel can be adjusted by adjusting the potentiometer resistance 8. The arrangement may be modified by taking the grid potential from the winding 2 or 3. The method can be used for automatic currentregulation, e.g. of an electric motor, by connecting the exciting winding 3 of the magnetic circuit either across or in series with a resistance in the armature circuit of a direct current motor. Fig. 4 shows a full-wave rectification system wherein two discharge vessels 10, 11 supplying a load 12 have their grid circuits linked to separate magnetic circuits 13, 14 which are each provided with direct and alternating current excitations, the alternating current excitations being connected in the same sense, while the direct current excitations are in the opposite sense. Either or both exciting currents can be varied, for example, when supplying a direct current motor its speed may be optionally regulated by altering the strength of the alternating current, or automatic regulation may be effected by making the polarizing direct current dependent upon the load. In a further modification a magnetic circuit is provided with two alternating current excitations which are displaced in phase with respect to each other, while a third winding is connected to the grid circuit of the discharge vessel to be controlled.