Patent ID: 6281784
Filing Date: 2001-08-28
Classification: H04B

Abstract:
A monitoring device for an electric lamp system including a ballast, a first electric lamp, and a second electric lamp connected together and energized over an alternating current power line installation, the monitoring device comprising:a current sensing circuit to sense electric current at a power input of the ballast;a first comparator connected to the current sensing circuit to compare the sensed current to a first reference;a second comparator connected to the current sensing circuit to compare the sensed current to a second reference; anda microcontroller connected to the first and second comparators and programmed to output for transmission over the power line respective codes corresponding to respective outputs from the first and second comparators, wherein the respective codes include a first code output in response to the first and second comparators indicating the first and second lamps are conducting operating current, a second code output in response to the first and second comparators indicating one of the first and second lamps is conducting operating current and the other of the first and second lamps is not conducting operating current, and a third code output in response to the first and second comparators indicating neither of the first and second lamps is conducting operating current.