Abridgment of combined light and power systems for A-C. secondary networks

The increase of a-c., 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. A study of the effects on seven types of equipment concerned showed 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. If the operating companies decide to employ the combined light and power system universally for secondary networks, it is urged that they will soon apply the practise of standardization to the combinations of connection and voltage. In this regard, due consideration should be given to the bearing of numerous trends in the industry. Widespread discussion of the situation is now desirable.