GB424022A - Improvements in and relating to arrangements employing electric discharge devices for connecting a load to a supply - Google Patents

Abstract

424,022. Converting ; switching systems for consuming devices. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London.-(Assignees of Langmuir, I. ; 1176, Stratford Road, Schenectady, New York, U.S.A.) Oct. 18, 1933, No. 28848. Convention date, Oct. 22, 1932. [Classes 38 (ii) and 38 (iv)] [See also Group XL] In an arrangement in which a load containing inductance is supplied from a D.C. source through a valve, means are provided for absorbing the transient voltages produced when the current is suddenly interrupted in the valve, comprising a resistance having a negative impedance voltage-characteristic connected in parallel with the load. In the form shown in Fig. 1 a load 12, 13 is supplied from a D.C. supply 10 through a valve 11 provided with means for applying a positive or negative bias to its grid. Commutation of current through the valve 11 is obtained by means of a condenser 16 and a grid controlled auxiliary valve 17. Connected in parallel with the load is a resistance 21 having a negative impedance voltagecharacteristic in series with a rectifier 22 which prevents current flow during normal operation. When commutation takes place the surge due to the inductance in the load circuit passes through the resistance 21. Fig. 2 shows a parallel type inverter having auxiliary valves 38, 39 connected in series with the main valves 36, 37 and a resistance 41 having a negative impedance voltage-characteristic connected in parallel with the transformer primary 34. The valves 37, 38 cause the maximum voltage of the winding 34 to be retained on the condenser 40 until the moment it is desired to commutate. The resistance 41 forms a short-circuit path for the current surge which occurs at commutation. Specification 292,110, [Class 38 (ii)], is referred to. Reference has been directed by the Comptroller to U.S.A. Specification 1,823,684.