A novel technique for energy savings by dimming high pressure sodium lamps mounted with magnetic ballasts using a centralized system

The return on investment from adopting centralized energy saving systems for street lighting can be compromised by voltage drop in long distribution lines. Large, centralized systems can reduce the output voltage sufficiently to dim distant high intensity discharge lamps. In this paper, the authors explore alternative dimming techniques and study the behavior of a 400 W HPS lamp when supplied by trapezoidal or rectangular voltages rather than the conventional sinusoidal supply. The efficiency and effectiveness of these alternatives are assessed by means of laboratory experiments.

► Alternative dimming techniques for centralized energy saving systems are explored.
► Unconventional supply voltage waveforms, trapezoidal or rectangular, are studied.
► A 400 W HPS lamp, mounted with magnetic ballast and capacitor, is considered.
► The efficiency of techniques are assessed by means of laboratory experiments.