The anticipation of demand, and the economic selection, provision and lay-out of plant (power systems)

Abstract

The author points out that the problem of dealing with growth in the electric supply business is radically different in nature from that of the telephone business and gives an instance to illustrate the nature of the difference.To make a fair comparison with a telephone system covering a considerable area, he assumes that for comparative purposes one might deal with an area having a radius of 10 or 15 miles from the generating centre and that an alternating current system of distribution is adopted.The problem divides itself into three main heads: (1) Distribution; (2) Feeder system, and (3) Generating plant.(1) The distribution system is, of course, the root of the whole matter and it is impossible to formulate any general rules or system, especially when there is a considerable development in new buildings. The matter becomes still more difficult when factories spring up in unlikely places.Reference is made to some rough figures indicating the load which may be expected under certain circumstances, the size of distributors which might be employed, and to a flexible system which enables additional load to be handled.(2) It is pointed out that the feeder capacity must be considerably in advance of the existing distribution load, as it is not a paying proposition to put in very small extra- high-pressure feeders. Considerations of duplicate feed and economy in copper covering a given area indicate a pioneer single-line system, forming eventually part of a ring or interconnected network.(3) The problem of dealing with the situation in the generating station is one which, in future, will be very largely out of the hands of supply undertakers, and the best method is undoubtedly to plot a curve indicating the maximum load experienced from year to year. From such a curve future tendencies may be closely approximated, and the problem then resolves itself into a convenient size of unit.It is pointed out that the most economical arrangement is generally to have units of the same size; this reduces the proportion of spare plant and has certain advantages in connection with lay-out and so forth. This matter, however, is too large to be gone into at this time and is dealt with only in a general way