GB801596A - Circuit for energizing at least one gaseous electric discharge lamp - Google Patents

Abstract

801,596. Supply systems for space-discharge lamps; protective arrangements. CLAUDE PAZ ET VISSEAUX. Nov. 25, 1955 [Nov. 26, 1954], No. 33867/55. Class 38 (4). In a discharge lamp circuit comprising a large magnetic leakage transformer having a primary winding 8 connected through a condenser 3 across an A.C. source and at least one secondary winding 5 energizing one or several series connected discharge lamps 7, at least the greater part of the secondary winding and possibly also at least a portion of the primary winding is shunted by a resistor 6 having a very high negative temperature coefficient of resistance and whose ohmic value is high when the lamp discharges normally but decreases largely and gradually when, while the circuit is still energized, the lamp discharge current is either nil or very small during at least every other half-cycle of the source. Thereby, should the lamp rectify in operation, or fail to strike the consequent voltage rise in the primary circuit, which may then be near resonant and produce dangerously high voltage and currents, is prevented by the transformer open circuit voltage causing the resistor 6 to heat up, pass a higher current, and constitute a lead of the same order as that of the lamp when discharging normally. As shown, the transformer is double wound, the large magnetic leakage is provided by a shunt 4, and the circuit is operated in parallel with a known lagging current lamp circuit to prevent flicker or stereoscopic effect and to improve the power factor. But in other embodiments, not shown, the latter circuit is not provided in which case an inductor may be connected across the input terminals 9, 10 to improve the P.F., and the transformer may be auto-connected, one end of the secondary winding being connected to an end or to a tapping on the primary winding and the resistor 6 being connected across both windings. The lamp may have, not shown, an outer starting band connected to one electrode through a resistance and when there are several lamps they start either simultaneously or successively. The transformer may be of the shell type.