ABSTRACT
Every ballast design must be a compromise of size, weight, shape, performance and cost. The simple reactor-type, electromagnetic lamp ballast consists of a core and coil assembly, to which is often added a capacitor to correct the line power factor. Other electromagnetic lamp ballasts are basically a modification of the reactor ballast’s construction. There are many characteristics that influence the design and performance of ballasts used with discharge lamps. Almost at the very onset of fluorescent lamp usage, it was found desirable to operate two lamps from the same ballast. One of the lamps is connected in series with an inductor, while the other lamp is in series with a capacitor, plus an inductor, which is still needed to help limit the current. Series sequence-start ballasts are used to operate two-lamp circuits, but because of their unique design, they can be made smaller, lighter and consume less power than conventional lead-lag ballasts.
