| 摘要 |
A ballast (10,20) for powering a gas discharge lamp load (30) comprises a protection circuit (300,600) operable to monitor an electrical signal (40) in the ballast and disable the ballast for at least a predetermined period of time in response to a disturbance wherein at least a portion (44) of the electrical signal (40) exhibits a time-rate-of-change that exceeds the time-rate-of-change of the signal during normal operation of the ballast and gas discharge lamp load. Protection circuit (300,600) is capable of disabling the ballast within a response time that is less than twice the period of the electrical signal. In a preferred embodiment that is suitable for ballasts with driven-type inverters, protection circuit (300) comprises a latching device (310) and a triggering circuit (330). In a preferred embodiment that is suitable for ballasts with self-oscillating type inverters, protection circuit (600) comprises a pull-down circuit (640) and a negative voltage source (610).
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