Improvements in or relating to electric circuit arrangements for operating an electric discharge device from an a.c. supply

摘要

655,000. Supply systems for space discharge lamps. GENERAL ELECTRIC CO., Ltd., and WILLOUGHBY, A. H. Oct. 11, 1948, No. 26464. [Class 38 (iv)] An electric discharge device particularly a high pressure lamp 5 has a starting circuit independent of the operating circuit and which applies to the lamp a plurality of pulses in rapid succession substantially in synchronism with the peak values of each half cycle of the A.C. supply voltage. Preferably the means producing the pulses is rendered inoperative when the lamp discharge is fully maintained. The pulses are generated by a transformer having its secondary winding 14 connected across the lamp through a spark gap 9 and its primary winding 15 energized either direct from the A.C. source 1, 2 (Fig. 1, not shown), or from a D.C. source 16 through the contacts 17 of a relay 19 responsive to the alternations of the A.C. source. In the former arrangement a peaky transformer is employed and in the latter a high voltage transformer. To render the pulse generator inoperative when the lamp discharge is fully maintained a relay 7 responsive to the lamp discharge current opens contacts 13. A high frequency choke 8 and condenser 81 are included in the lamp-operating circuit to prevent the pulses being fed back into the supply mains. The spark gap may be provided with a de-ionising air blast. According to the Provisional Specification the relay coil 19 may be connected to the D.C. source through the secondary winding of a transformer having its primary connected across the A.C. source, thereby providing one pulse every cycle of the A.C. supply.