GB330861A - Arrangement for converting direct current into alternating current by means of electric vacuum valves - Google Patents

Abstract

330,861. Maschinenfabrik Oerlikon. Nov. 9, 1928, [Convention date]. Vapour and vacuum or lowpressure apparatus, arrangements of.-In an arrangement for converting D.C. to A.C. by means of electric vacuum valves in which the valves are rendered electrically conductive by alternating rhythmic ionization, condenser circuits in parallel with the valves are connected through the windings of a transformer so that the condenser discharge current at the moment of ionization of one valve induces a quenching current in the condenser circuit of the other valve. In the circuit shown in Fig. 1, assuming that, at a given moment, the valve V1 is conductive whilst the valve V2 is non-conductive, then the condenser C1 is short-circuited through the valve V1 whilst the condenser C2 is charged up to the potential of the anode A2. If now the valve V2 be energized through the ionizing anode Z2, the condenser C2 will discharge via the transformer T1 and valve V2 and the current induced in the circuit of condenser C1 will quench the valve V1. As the potential of the anode A1 rises the condenser C1 becomes charged and when valve V1 is rendered conductive the same cycle is repeated. The rhythmic ionizing of the valves V2 and VI is thus accompanied by a rhythmic quenching of the valves V1, V2. Fig. 2 shows a modification of the above circuit so that in the event of overload or short-circuit the valves are rendered non- conductive and the source of ionizing potential cut off. If the current from the source Q increases above a certain amount the switch Sch opens and removes the short across the part of the third winding of the transformer T1 so that the whole of the turns become effective and a voltage is induced in the two condenser circuits and the valve that is conducting at that moment is cut out. To cut off the ionizing supply the return lead 3 has in series a valve V3 across which is connected a circuit 03, R3 coupled by a transformer T11 to the positive lead from the source Q. Normally this valve is conductive, but when switch Sch opens due to overload the whole of primary winding of transformer T11 becomes effective and a potential is induced in the condenser circuit which quenches the valve V3.