THE POWERHOUSE.

Taranaki Daily News, 11 September 1916, Page 6

THE POWERHOUSE.

INSTALLATION OF FURTHER MACHINERY. At to-night's meeting of the Borough Council, Sir. R. H. Bartley, electrical engineer, will submit the following report:— After very careful consideration of this matter I have arrived at the conclusion that it will not be advisable to delay the installation of s further machine at t'hc powerhouse any longer than is absolutely necessary. This matter, is made more urgent by the fact that the new unit is to take the place of tli* existing two 45 k.w. machines, and also supply extra power. Consequently the 45 k.w. machines will not be available for use during the installation of the new machine and the powerhouse capacity would be reduced by 90 k.w. which *'t this period it could stand, but later on it may be very difficult to do without it, especially should anything happen to one of the other machine!?. A fenfigures will serve, to prove this statement. The total capacity of generating plant at the powerhouse is:—Two 250 k.w., 500 k.w.; two 45 k.w., flO k.w.; one 90 k.w.; total 08(1 k.w.; or it may he easier understood if f confine myself to horse power; thus the total capacity of the powerhouse is !)0" home power. Of this appro;, lately 4S-h.p. is consumed in the transformation losses in connection with the two 4a k.w. and the i) 0 k.w. machines, leaving only 852 h.p. available for transmission from powerhouse. In addition must bo added a uu-thcr loss of approximately 10 per cent ior distribution, leaving ' WO.B hor.se power available. The maximum load reached to date is COO horse power, leaving a margin of 100.8 horse power Personally I have made no tests and hove- seen no tests taken on tlhc machines at the powerhouse, but I'am informed by the engineer in charge of the powerhouse and by the late electrical engineer that the two 250 k.w. machines will not stand up to more than a 203 k.w. load, and judging from tlheir present condition, I am very apt to believe it, and this being the case il,o margin of power is almost exhausted, leaving only j33 horse power. Should a, further 250 k.w. machino ho installed and the two 45 k.w. sets removed the case would be altered as under. Total capacity of powerhouse:—Three 250 k.w., 750-k.w.; ono 00 k.w.; total 840 k.w., or 1120 horse power. Twentyfivo Jhorse power of this would be consumed in transformer losses on the flO k.w. machine against 48 h.p. in the previous case, leaving lOffO h.p. for transmission from the powerhouse. The additional losses of 10 per cent, for distribution would leave !>SG h.p. available. and supposing that the two' 250 k.w. machines cannot bo made to give full load ! the margin is then 353.4 h.p, 1 It would be advisable to instal ma- ' chines of greater capacity than 250 k.w. Mn separate units and tills size of machine should constitute a standard for the New Plymouth powerhouse. The reason for this standard is that in ttie event of a machine breaking down (ii it were larger than 250'k.w.) no other of the single units would he capable of taking its place, etc., and being of large capacity the lay up would be serious. The current procedure is therefore to take out the two 45t;k,w. machines and replace with one 250 k.w. Then take out the !XI k.w. machine and replace with one 250 k.w. I would advise that these alterations should follow each other as soon as possible, as it is on the latter that the station will rely for its stand by, besides increasing its efficiency. The question now arises as to the water power. I have likewise given this careful consideration and in doing so I have been compelled to accept the figures as to the minimum flow of the river from past estimates. These figures can only be obtained by careful observations over lengthy periods, and I have traced the reports of the various engineers on this subject and <?an only find two references to tlhe matter, one bv Sir. H. Black and the ot'b?r by Mr. F. Black, an dthe latter, U is apparent to me, has based his estimate on that of the former, Mr. H. Black, who put \!,to. minimum flow of the river down at 4000 cubic feet ;ier minute. I can find no information as to the duration of this minimum flow', and therefore cannot calculate the asdistance that the storage in the dam would have at such times, but it is quite obvious that when the machines as above mentioned are installed, the statinn limit will have been reached. TSiis minimum flow, I should say, must only form a very small proportion of the and at other times the station woula be capable of producing much more powei than I have outlined, but it must be capable of supplying it at all times, and to do this would require <some auxiliary power capable of making up the difference when the river is at its minimum. I am not prepared 'here to say what power it -hould be, either steam, gas, or by tapping the river higher up or lower down, and using the water over again. This would need more careful consideration than I have at present given it befors arriving at any decision, and there is also another important factor to cashier. The present tunnel from the da".;: to forebay will' not carry the water to supply more than approximately 700 k.w. at the powerhouse, and this would either require a new tunnel or the head of. water in the dam increased. The new tunnel is to be much preferred, as it could be made large enough to keep the velocity of the water low, and thus prevent tiie scour. I would beg to state in conclusion thnt this report is dealing with a matter that is of great importance, and means much to the general advancement of the .'lee-tric power and lighting and tramway se'iiemcs. in fact, tihe whole future hangs on it, and I would respectfully ask that at the appointment'of the new Borough Engineer, lie be requested, in conjunction with myself to consider the latter part of this report and furnish the Council wit'll a complete scheme fo? the future*