GB420872A - Improvements in or relating to vapour or gaseous electric discharge devices - Google Patents

Abstract

420,872. Converting. WESTINGHOUSE ELECTRIC & MANUFACTURING CO., East Pittsburg, U.S.A.-(Assignees of Ludwig, L. R. ; 738, Princeton Boulevard, Wilkinsburg, Pennsylvania, U.S.A.) May 11, 1934, No. 14247. Convention date, May 27, 1933. [Class 38 (ii)] [See also Group XL] The exciting anode 4 of a mercury vapour discharge tube is surrounded by a shield 7 which extends close to the cathode 3 ; the shield is insulated from the anode 4 by spacing or a quartz inset, and its potential is controlled by a switch 11. The main discharge to the anode 2 cannot be instigated even if this anode is at a positive potential, until the shield is made positive. As shown in Fig. 1 the main discharge is interrupted by means of a circuit including a condenser 13, battery 16 and switch 15 ; a spark-gap 14 is placed across the condenser 13. For use in converting continuous to alternating current, two discharge tubes 1, 1<1>, Fig. 2. are connected to the ends of an inductance 24 in the alternating circuit, the mid-point 23 being connected to the generator 21. A condenser 27 connected between resistances 26, 26<1> in circuits to the shields 7 controls the potentials of these shields and the working of the tubes. Instead of mercury cathode and vapour filling, thermionic cathodes and gaseous filling may be used. The shield need not completely surround the anode 4. A number of anodes in one tube can be controlled by a single shield 7. In an inverter system using two tubes the arc in one can act as the extinguishing means for the arc in the other.