| 摘要 |
An electric arc detection apparatus and method is based on AC current rectification phenomena in air plasma that causes low frequency amplitude modulation of high frequency currents and voltages in the ballast when disconnecting the lamp (Lamp) from the electronic ballast with power applied . A protection circuit (R25, C27, D44, D45, C28, C27, M4) shuts off the invert er (M1 and M2) of the ballast so the duration of the arc is diminished so that the arc becomes almost non-visible. The protection circuit senses the input of the ballast inverter resonant tank (C3 and L1), which is free of transients caused by resonance, detecting arc rectification frequency which is about 25 - 30 times less than the inverter carrier frequency, and turns on a switching device (M4) for stopping oscillations in the inverter (M1 and M2). When the lamp (Lamp) is reconnected to the ballast, it resets the protection circuit and the ballast inverter restarts automatically.
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