ELECTRIC SUPPLY

Nelson Evening Mail, Volume LXX, 16 June 1936, Page 8

ELECTRIC SUPPLY

SOME SUGGESTIONS (To The Editor) Sir, —While the City Council and the Hume Pipe Company and the Government are stalling for time among themsel-ves it seems that the citizens of Nelson hardly realise that their electricity supply is in a precarious condition. The turbine unit at the Power Station has been running continuously, 24 hours a day for seven years, and there has simply been no opportunity to even inspect the condition of the rotor and main bearings. Minor adjustments to auxiliaries that have been necessary are made on Sunday mornings. It speaks volumes for the reliability of the modern steam turbine that there has been no major breakdown, but even a layman must appreciate that it is tempting Providence to depend entirely on one machine that has been running so long. The position is that a failure of the turbine would mean the greatest inconvenience for the following reasons. The rated capacity of- the turbine is 750 k.w. and with its overload it is capable of running at something over 900 k.w. for an hour or two. The two original reciprocating sets are capable of a maximum of 300 k.w. each, i.e., a total of 600 k.w. including overload. As the maximum demand this winter will probably rise to 1000 k.w., it is obvious that a failure of the turbine would be disastrous. It would take at the very least three months to obtain spares and get the machine running again. In the meantime there would be no hope of the reciprocating sets meeting the demand. They were not capable of doing so eight years ago. There is another aspect to consider. The reciprocating sets consume 60 to 70 per cent, more steam for the same electrical output, hence one reason why the only times they have been used during the last few years have been on Sunday mornings for a few hours while routine jobs are attended to on

the turbine. These sets ai’e obviously antiquated, most uneconomical, inadequate, and not much better than useless lumber occupying valuable space. It is of no use criticising without offering some constructive suggestions. The following may therefore be worthy of some consideration. I should suggest the duplication of the present 750 k.w. turbine set and not the installation of a larger machine for the following reasons: (1) The present boilers at a pinch could run both turbine sets to their full overload capacity—nearly 2000 k.w. —much more than the maximum demand is likely to be for ten years. (2) Another 750 k.w. turbine could be installed in the present building by removing one of the reciprocating sets and carrying out similar work to that done when the present turbine was installed. (3) The pump line and auxiliaries would be interchangeable if the new set is of the same size as the one we are now depending on. (4) One set of spares would serve for both machines if they are of the same size and type. A much bigger range of spares could be carried at a minimum expenditure. If one of the reciprocating sets is removed switchboard space would be available for the new turbine without any extensions. It will be seen-fmm the above that the electrical requirements of the city can be served for a good many years to come by the expenditure of a much smaller sum than it is proposed to expend on a large set of, say, 1000 or 1500 k.w. A larger set will require more boilers, extension of boiler house, extension of engineroom and switchboard. The two smaller .units with a total capacity of nearly 2000 k.'w. would make a satisfactory standby plant even if a hydro plant is in operation within five years, and would be capable of meeting ordinary power demands for many years after that. Later, if we still require steam power it would be economical to put in a complete new unit of 1500 k.w. —i.e., the total capacity of the combined two 750’s. A larger machine at the present juncture would make the present turbine an orphan not capable of acting as a standby to the larger machine by itself. Lots more could be written on the subject, but I should like to make these points clear. Something must be done and that right soon. We must have another unit here and working before next winter or we are liable to be in a pretty fix. Unnecessary expenditure of public money must be avoided and a municipal concern should be just as businesslike, in its methods as a private company. In our Council we have some shrewd business heads, and I take it that they are willing to accomplish what' is required with no more expenditure of capital than is absolutely necessary. They would be well advised to give the above suggestions some serious consideration.— I am, etc., TRUE ECONOMY. Nelson, 13th June.