ELECTRONIC INVERTERBALLASTING SYSTEMABSTRACTAn electronic ballast employs an electronicinverter which drives a main power transformer across theoutput of which terminals are connected for a pluralityof fluorescent lamps. A high impedance capacitor isconnected in parallel across at least one and less thanall of the fluorescent lamps. An anxiliary transformer isinterposed between the output of the main power transformerand the cathode elements of the fluorescent lamps. Uponstart-up, the high impedance capacitor initially createsa bypass around lamps with which it is connected in parallelto thereby apply the entire high voltage output of thepower transformer to start the remaining lamps. Once theselamps are started the voltage drop thereacross is reduced toallow the high voltage output to bypass the high impedancecapacitor and start the lamps connected in parallel therewith.The auxiliary transformer provides good magnetic coupling andlow voltage to the cathode elements of the fluorescent lamps.A separate feedback transformer smaller than the main powertransformer operates the electronic inverter to avoidoperation of the main power transformer at its saturationlimits.- 1 -
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