Effects of voltage sags on different types of ballasts for 150-W HPS lamps

By F Ortiz et al

Nowadays, energy efficiency is a hot topic in a very demanding environment. Improvements in lighting applications, which are a significant point of energy consumption, would be very much welcomed. Electronic ballast may serve this goal, since it is focused on achieving energy savings, reduction in the utility line's harmonic content and reactive power, and implementation of dimming control and some other parameters of interest in lighting applications.

On the other hand, power quality problems are very common in our power system, and any new electrical device should be designed taking them into account. One of the typical problems in electrical distribution systems is voltage sags. These have a great incidence in electrical equipment connected to the network in the same area. The sags cause more damage than other disturbances because they occur with greater frequency.

In this work, the effects of voltage sags on several 150 W high pressure sodium lamps combined with two different types of electronic ballast have been studied. One of the ballasts supplies the required voltage to minimize the reactive component in the resonant inverter while the other regulates the power supplied by the utility line to be constant in the long term, the resonant inverter also being in open loop at constant switching frequency providing the short term stability.

The results of these electronic ballasts will be compared with those obtained with traditional electromagnetic ballast. The influence of the lamps' age will be also considered in the approach. The final goal of this study is to improve the performance of the ballast prototypes under voltage sags.