Plc controller and discharge lighting ballast receiver with high noise immunity

Abstract

A power line communication system communicates a ballast dimming level to an electronic ballast over an AC power line. A power line controller is operable to generate the ballast control signal and to insert that signal on the AC power signal being transmitted over the AC power line. A power line receiver receives the AC power signal and extracts the ballast control signal from the AC power signal to generate the dimming level signal corresponding with the desired ballast dimming level. To insert the ballast control signal on the AC power signal, the power line controller has a transformer coupled to the signal pattern circuit. The secondary winding of this transformer is connected in series with the AC power line to insert the ballast control signal on the AC power signal. This AC power signal is then transmitted to the electronic ballast. To extract the ballast control signal out of the AC power signal, the power line receiver has a resonant circuit connected in series with the AC power line. The resonant circuit should be tuned to transmit the ballast control signal and to filter out the AC power signal. A dimming level sensing circuit then senses the signal pattern on the ballast control signal and generates a dimming level signal corresponding to the desired ballast dimming level.