Field experience with high-frequency ballasts

The Energy Conservation Office of the University of California at Berkeley has installed over 35000 high-frequency ballasts, produced by three manufacturers, in the period from 1986 to the present. The quantities of defective ballasts that are returned to manufacturers for replacement are used to estimate the failure rate of these ballasts under field conditions. It is concluded that careful selection of high-frequency ballasts will result in 20-30% energy savings and reliable quiet flicker-free operation. They provide a rapid payback when specified for new construction or when used as the replacement for failed magnetic ballasts. Depending on operating hours and the cost of electricity, the payback may be acceptable even when high-frequency ballasts are used to replace operating energy-efficient magnetic ballasts (in conjunction with cleaning and lamp replacement). The availability of partial light-output ballasts makes it feasible to fine-tune light levels in spaces that are overlit, gaining a proportional decrease in energy use