| 摘要 |
A ballast ( 20 ) for powering one or more gas discharge lamps ( 70,72,74,76 ) comprises an inverter ( 200 ), an output circuit ( 300 ), and an arc protection circuit ( 400 ). Arc protection circuit ( 400 ) monitors an electrical signal within the output circuit ( 300 ). When an arcing condition occurs at the ballast output connections ( 302,304,306,308,310 ), the electrical signal includes a high frequency component having a fundamental frequency that is much greater than the normal operating frequency of the inverter ( 200 ). In response to the high frequency component exceeding a predetermined threshold, arc protection circuit ( 400 ) disables the inverter ( 200 ) for a predetermined shutdown period. Arc protection circuit ( 400 ) also provides a restart function for periodically attempting to ignite and operate the lamps. Arc protection circuit ( 400 ) is preferably realized using a microcontroller integrated circuit ( 440 ) with associated discrete circuitry, and is especially well-suited for use in ballasts for powering multiple lamps via a current-fed self-oscillating inverter and an isolated parallel resonant output circuit.
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