| 摘要 |
A zero current crossing capacitive switching scheme for controlling the switching of a capacitor into and out of an HID lead ballast circuit at a time when a current through the capacitor is at or near zero. The capacitor switching enabling bi-level operation of an HID lamp such that the HID lamp operates at full power mode or in a reduced power mode. The zero current crossing is achieved by delaying the capacitor switching, a duration equal to about 5 DEG to 10 DEG lag from the zero volt crossing. The device can be used in a method of controlling a plurality of HID lamps using an isolated class 2 wiring scheme. Potential damage to the HID lamp caused by aborted lamp ignitions is also disclosed. The method includes suppressing off input signals during the warm up period.
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