ELECTRIC POWER PROBLEMS

Dominion, Volume 12, Issue 142, 11 March 1919, Page 6

ELECTRIC POWER PROBLEMS

MANGAHAO AND THE CITY PLANTS

A SYNCHRONISING TROUBLE

The prospect of Wellington being in the position to use the electrical energy that is to be developed by water power from tho Mangahao Hiver for its chief utilities—the tramways and. lighting plants—is not quite the 'simple matter that it would appear to be at first glance to the'infnd that lacks a, technical knowledge of tho problem involved. For example, one easily assimilated fact is that the Government, in making its arrangements as to changes, can only supply the current needed on the basi§ of the peak load in Wellington; that is to say, that the Wellington City Council would have to be prepared to. pay all the year round—for every hour of every day—for current sufficient to supply n.ll demands on the "highest "peak" during tho year, say between 5 and 6 p.m. on n day early in My. That cannot very well be avoided, n5 the Government, in laying its plans, must provide for such a "pull" on its plant, even though for half the year the demand is only 59 per cent, of the peak load in mid-winter. Then, again, the city will require to have its stand-by plant, with a partial staff always, available for duty' in case of a breakdown. In that regard, Christchurch,, depending on the Coleridge supply,' has had rather sad experiences, which we in Wellington have never experienced with our. steam-driven plant. Our plant is in fairly good order, and no fault can be found with our big turbine engines, but before the existing'plant can be used as a stand-by to the Mangahao hydro-electric supply some costly alterations will have to be made. Our tramways supply is a direct one. whilst that generated at the lighting powerhouse in Harris Street is a single-phase alternating current (with a cycle-of 80), whereas -the current to be generated at the Mangahao power-house will be threephase alternating (with . the standard cycle of 50). It is the difference of ''periodicity'' that causes all the trouble, and is likely to cost the city a deal of money before our plants are adaptable as a stand-by to -'the proposed new source of power supply. It may be that'our plants may be able to be made productive by reducing our peak load, and any. thing that may be accomplished in that direction will lessen the permanent demand on the Government supply. It may even pay the city to use storage batteries with a view' to easing the peak load. That is a matter that concerns ,the city alone, as the liability of the Government will be to.supply the "peak" whatever it may be. . So Jar the City Council has had no definite pronouncement in writing as to the price at which the Government will be able <t> jupplv current from Mangahao, but Mr. Evan Parry (the Government hydro-electric expert) .has made verbal statements as to the probable approximate cost (estimated at per kilowatt per annum), which, calculated against- the expenditure of a normal year's working, shows that a considerable saving will be effected by the utilisation of the power from Mangahao. There is, too, the prospect of the Government making an annual allowance for . the stand-by plant as the existence of such would enable it to cut. out a set (at the Mangahao power-house) for overhaul, instead of the Government having to provide its own stand-by plant for such necessary work. .Of- the-24.000 horse-nower to be developed at Mangahao. 10.000 • horse-power is to be reserved for Wellington. At present the city's normal demand requires between 5000 and 0009 horsepower. A LOAN OP £150,000 FOR CHRISTCHURCH LIGHTING AND POWER. By TelegraDh-Prcss Association Christchurch, March 10. The Christchurch City Council decided last night to raise a loan of ,£150,090 for the purpose of carrying out an extension of the electric lighting and power schemo and the installation of a stand-by plant to obviate the trouble caused last winter, when a snowstorm brought down the Lake Coleridge transmission lines.