| 摘要 |
1,108,736. Supply systems for discharge lamps. GENERAL ELECTRIC CO. 28 Feb., 1966 [23 March, 1965], No. 8596/66. Heading H2H. Two groups of series-connected filamentheated discharge lamps L 1 -L 12 are supplied with alternating current of substantially square waveform by connecting between each group and its respective A.C. mains supply 18, 19 and 21, 22, capacitors C 1 C 2 and C 3 C 4 , each series combination of lamps and capacitors being connected in parallel with a saturable reactor X 1 X 2 arranged to saturate at a predetermined point in each half cycle of the mains supply, e.g. at or near the peak voltage. Operation of the circuit is discussed with reference to typical voltage waveforms across the capacitors, reactors and lamps, Fig. 5 (not shown), the lamp reversing suddenly in each half cycle when the reactor saturates and the capacitors discharge through the reactor-lamp circuit. The other circuit elements are conventional in construction and function. In another arrangement for two series-connected filament-heated lamps, Fig. 2 (not shown) the reactor is replaced by a five layer diode, which in turn may be replaced by other bidirectional semi-conductor switching arrangements, e.g. a silicon controlled rectifier or a four layer diode in a full wave bridge. The saturable reactor may be used as the starting transformer for the lamp circuit and such an arrangement, again for two series-connected lamps, is described, Fig. 4 (not shown). In this arrangement a further reactor (X3) is provided in series with the A.C. supply to perform the ballast current-limiting function and to isolate the lamp operating loop from the A.C. supply when the saturable reactor saturates to effect reversal of the lamp current. |
