D.—l

54

As compared with last year these figures show a larger proportion of country supply, there being 1,990 county consumers as against 1,250 last year. With the development of the Electric-power Board districts it is anticipated that in the, early future the number of country consumers will increase very rapidly, thus fulfilling the main object of hydro-electric supply in stimulating the output of primary products, and attracting the population to the country districts. With regard to the systems of supply, the fifty-five stations of the Dominion (Table P) are operating on the following systems :— Number. Kilowatts. Proportion. Three-phase, 50 cycles. . .. .. ..18 26,690 58-3 Three-phase, 60 cycles. . .. .. .. I 550 1-2 Single-phase, 40 cycles .. .. .. I 235 0-5 Single-phase, 50 cycles .. .. ..4 1,335 2-9 Single-phase, 60 cycles .. .. .. I 75 0-2 Single-phase, 80 cycles .. .. .. I 4,500 9-8 D.C., 3-wire, 460 volts. . .. .. ..21 11,251 24-6 D.C., 2-wire, 230 volts.. .. .. ..7 794 1-7 D.C., 2-wire, 550 volts.. .. .. ..I 375 0-8 55 45,805 100-0 The three-phase 50-oyclc system, has been adopted as the standard for the. Dominion. To enable supply to be taken economically from the Government hydro-eleotric-supply systems it is necessary that all the distribution-systems as far as possible should be changed over to this standard system. Already 58-3 per cent, of the plant capacity installed, is on the standard system, and several other plants are making arrangements to change over in the near future. It is thus anticipated that within a. couple of years over 75 per cent, of the installed capacity of the Dominion will be on the standard system, with consequent economy in interchange of power ami convenience in keeping spares and stocks. With regard to the cost of operation (Table G), twenty-seven out of fifty-five systems are operating at a profit after paying capital charges, and the balance at a loss. This is due mainly to the rapidly increasing costs. These should be met as early as possible, either by increased economy in operation, increased output, or, where these are not available, by increased charges. The comparison between the gross operating results of the North Island and the South Island systems (Table G) is valuable in view of the larger proportion of hydro-electric power in operation in the South Island. The figures for last year are as follows : North South ~, , . Island. Island. Population supplied .. ~ .. .. 307,489 229,354 536,843 Number of consumers .. .. .. .. 34,f07 24,342 58,449 Power installed, (kilowatts) .. .. .. 27,099 18,706 45,805 Maximum load (kilowatts) .. .. .. 16,717 13,999 30,716 Capital outlay .. .. .. .. £1,642,269 11, 6J J, 601 13,253,870 Units generated .. .. .. .. 42,233,651 57,661,879 99,895,530 Units sold .. .. .. .. .. 33,619,138 45,809,980 79,429,118 Units non-productive .. .. .. .. 8,614,513 11,851,899 20,466,412 Percentage, units non-productive .. .. 20-4 20-5 20-4 Total load factor .. . . . . , . 28-7 47-0 37-0 Total revenue .. .. .. .. .. 1372,940 1280,709 £653,649 Revenue per unit sold .. .. .. .. 2-66 d. l-46d. l-98d. Revenue per kilowatt I.II. maximum .. .. £22-3 £20-0 £21-1 Total working-expenses.. .. .. .. £233.158 £141,703 £374,861 Working-expenses per unit sold .. .. .. l-(i(id. 0-74 d. lT3d. Working-expenses per kilowatt: I.II. maximum .. £13-9 £10-1 £12-2 Total capital charges .. .. .. .. £102,417 £109,741 £212,158 Capital charges per unit sold .. .. .. 0-74 d. 0-57 d. 0-64 d. Capital charges per kilowatt I.II. maximum .. £6-1 £7-8 £6-9 Total annual costs .. .. .. .. £330,048 £249,085 £579,133 Total annual cost per unit sold .. .. .. 2-'lod. l-31d. l-75d Total annual cost per kilowatt P.H. maximum .. £20-0 £17-9 1:19-1 The present total capital outlay on electric-power supply in each of the two Islands is approximately the same (£1,600,000), but owing to the higher capital cost of hydro-electric planl the installed hydro-capacity in the North Island is less than in the South Island, where the majority of the plant is operated by water-power. On (he other hand, the load factor and the output in units arc higher in the South' Island (45,800,000 units sold) than in the North (33.(100.000 units sold) owing to the cheaper cost of production, and the total cost per unit sold is I -3d. in the South Island as compared with 2-4 d. in the North. Lawrence Bibks, B.Sc, M.lnst.C.E., M.1.E.E., Chief Electrical Engineer.