Combined Light and Power Systems For A-C. Secondary Networks

If the situation being created by the extensive use of combined light and power systems for secondary distribution is to be squarely met, widespread discussion is necessary. The increase of alternating-current low-voltage network systems employing automatic sectionalizing equipment has been very rapid. This move has been attended by a diversity of choice of combined light and power schemes for the secondary mains. Carrying this condition to its logical conclusion may result in an extremely complicated situation for apparatus connected to these mains. There might thus be imposed on the industry as a whole a heavy expense tending to cancel a part of the savings attributed to the advent of the combined system. Previous investigation of the probable effect of each of the principal light and power schemes on apparatus connected to the secondaries has been confined largely to general purpose motors. A study of the effects of six other types of equipment concerned showed, however, that general purpose motors are hardly more important than most of the other devices. This analysis included not only the applicability of existing apparatus standards to each of the combined systems but also the probable developments that the future may bring. For a comprehensive comparison of the various schemes it was found necessary to consider the commercial as well as the engineering aspects.