Comparison of Preregulators as Power Savers

Many modern computer, digital communication, and industrial control equipments are furnished dc power by series-pass regulated supplies. At the voltage and current required, these supplies frequently dissipate twice as much power as they pass on to be used. With increasing interest in conserving energy, it has become desirable to minimize the losses of the supplies. This can be done at modest cost by installing a simple preregulator which is itself relatively efficient. This paper presents the experimental results of comparing three methods of preregulation. The three methods chosen can be retrofit in many existing systems. The three are 1) ferroresonant transformer, 2) replacing existing rectifiers with SCR's, and 3) triac throttling of the input. Each of the three methods has some relative advantages, and each has its detractions. On balance, it appears from measurements reported here that triac throttling is the best method.