GB502255A - Improvements in circuit arrangements comprising a mercury rectifier having an ignition electrode - Google Patents

Abstract

502,255. Converting. GENERAL ELECTRIC CO., Ltd., and PRINZ, D. G. Sept. 17, 1937, Nos. 25302/37 and 14689/38. [Class 38 (ii)] In a circuit arrangement, including a dis. charge device having an ignition electrode, in which the circuit constants are such that a short ignition impulse is insufficient to effect ignition, provision is made whereby control is obtained either by altering the circuit constants sufficiently to render the ignition impulse effective, or by lengthening the duration of the ignition impulse. Due to the inductance 7, 8, Fig. 1 (14689/38), and capacity 6 in the circuit, an oscillatory discharge commences when the ignition electrode 9 receives an impulse, and under certain conditions the discharge current reduces to zero after the ignition impulse has ceased, and effective ignition fails to take place. Various ways of adjusting the circuit constants are described. The inductance 8 may be varied by an adjustable air gap in its core, or by means of a presaturating winding or by varying the number of turns. Alternatively, damping resistances may be connected in circuit to reduce the oscillatory component. This may comprise a thermionic valve, the effective resistance of which is adjusted by means of grid bias. The capacity in circuit may be varied to increase the frequency of the oscillatory component. To increase the duration of the ignition impulse, a " back up " circuit may be provided comprising a D.C. source 10, Fig. 1 (25302/37), connected through a control switch 9 to an auxiliary electrode 7, to give a sustained discharge when an ignition impulse is given to electrode 4. Opening the switch 9 renders the discharge device inoperative. In a modification of this, a condenser, connected between the cathode and electrode 7 through the resistance 8, is charged from the battery 10 through the switch 9 and a further resistance. In a further modification, the switch 9 is replaced by a light-sensitive cell. The arrangement may be provided with a relay to operate under fault conditions.