ELECTRIC POWER

Southland Times, Issue 22010, 9 May 1933, Page 8

ELECTRIC POWER

SOUTHLAND BOARD REPORT OF CHIEF ENGINEER YEAR’S OPERATIONS The chief engineer of the Southland Electric Power board (Mr L. B. Hutton), in his report on the activities of those departments under his control fipr the year ending March 31, states:— In general, the lake has been maintained at a high level; and that its "highest” was never below 9ft Bin, while its “lowest” was never lower than Bft 6in; and, moreover, on only two occasions did the level fall below 9ft Oin. This, as was to be expected, was during the period when the rainfall was low, and when there was no reserve of snow on the back of the catchment area to maintain the average inflow. The high rainfall for the year ending 1929 was due to an abnormal downpour of 17 inches which occurred in October, and was instrumental in providing the highest levels recorded in the lake, the Monowai River and the Waiau River. But even with this abnormal rainfall, the average_ river discharge was not as large as in the previous year. This serves to point out that figures of the village rainfall are no criterion of what occurs in the catchment area. In 1928 and 1929 we lost more water than we used, and in the remaining four years we have an average of about 75 per cent, excess water. Mr Hutton appends a table which shows that the number of units actually generated increased from 21,200,000 in 1928 to 24,500,000 units in 1933. The units available through excess water were 25,000,000 in 1928 and 17,000,000 in 1933. This accounted for a potential power of 46,700,000 units in 1928 and 41,500,000 in 1933. From the figures quoted Mr Hutton concludes that the ultimate station output is in the region of 40,000,000 units. Power House Figures. The following table provides an analysis of the power' house figures since 1927: — Per-

1932 is the only year in which we do not show a progress in units sold, and the 1933 figures are approximately where the 1932 should have been. Power House Lead Characteristics.

The following table details some of the more interesting load characteristics:—

The figures in the third column represent the actual load carried by the station, but for the years 1932 and 1933, do not represent the demand made on the station. In 1932, on several, occasions, it was such that we could not supply and had to trip load. In 1933 there was, on one occasion, a demand of 6,410 foi' half an hour, and on this and several other occasions, we were helped by the New Zealand Paper Mills. In both years arrangements were made beforehand for a reduction of demand from several of our large industrials, the total dropped being in the region 500 k.w. The normal demand which might be made on the station during certain periods in May and June is therefore just under 7000 k.w. Power Station. There is only one unusual occurrence to record—the replacement of thrust rings in No. 1 machine The machine was getting more and more noisy and it was deemed advisable to make an inspection, when the gener-ator-end thrust ring was found to be badly worn. The machine was taken out of use on the Saturday morning, new rings were cast in Invercargill and taken up to the job, and the machine was on the busbars again on Sunday night. While it was opened up, opportunity was taken to replace the thrust ring at the valve end as well. For the rest of the year everything was normal. The usual maintenance has been carried out . . . Some little attention has been paid to the apron below the spillway, where floods had caused erosion, and the last two chains of the Monowai River before entering the Waiau have to be watched against encroachment towards the power house. It seems likely that we shall have to erect a short length of glance wall to protect the last few yards of pa-pa formation, but this matter is not yet decided.

The transmission ‘ line has continued to function in a first-class manner, and it is pleasing once more to be able to record an absence of any stoppage due to defective transmission. This is due partly to our having a duplicate line to Winton, and an adequate tie system, which together enable us to give each section of line due inspection and overhaul, and partly to the excellence of the inspection . and overhaul itself, which must have been thorough to be so effective. This year a new system of overhaul has been developed, in which the construction parties at Winton, Invercargill and Gore each take their turn. Much of the work must necessarily be done during the weekend, and we are of the opinion that the quicker it is done the better will be the work. The Sub-stations.

Under this heading is grouped all the apparatus, both 66,000-volt and 11,000-volt, which handles the current from the moment it leaves the transmission lines until is passes out again on to either transmission or distribution. So far as the 66,000-volt part goes, we can report that it has been comparatively satisfactory. Some of the apparatus can never be eminently satisfactory, , because it is incapable of such performance; but by careful attention it has been made to perform certain services. The 66,000-volt air break switches continue to receive periodical -attention—we know their failings, and are prepared for them. This work represents a continual maintenance. The oil. circuit breakers at 66,000-volts continue to do their work well. At Monowai, the outdoor transforming and switching. station has functioned perfectly, handling all operations with ease.

The indoor part of the sub-stations has not been too good. At Winton we have had two flashovers, one involving the incoming panel at 11,000-volts and the other part of the busbar structure. Both occurred at night, and caused a temporary stoppage. The result of a failure such as this must be

seen to be appreciated, and when occurring at a time of low power station output, introduces certain leakage P®" cularities. However, we Lave realized for some time that an alterative route for the outgoing distribution circuits must be provided at Winton, and the work is being proceeded with as opportunity offers. Gore sub-station has been better, only minor maintenance requiring attention. Invercargill substation has been on a par. Construction Work. There have been no large extensions during the year, and in general, owing to the guarantees required, it may be concluded that the day of long extension is past. A large proportion of the work of the construction parties has consisted in the provision of service to the 171 new consumers, who have come on to the system. This may entail one or more of several operations -—an extension of 11,000-volt or 400volt, an addition of wires, the removal of wires, the erection of transformers, or the alteration of their position. Indeed, consequential alterations, following on new jobs, often form the major part of the work, and have to be undertaken if the new service is to be given economically. Another major work was the sorting out of single phase customer groups which were being afforded a three phase service. Many of these were re-arranged, and in a number of places, the three-phase transformer was replaced by a single phase one. A work just as important as new construction is maintenance, and in this connection it is pleasing to report that an inspection was made by the Public Works Department after Christmas, and that we appear to have satisfied their very strict requirements. Each area has endeavoured, so far as possible, to completely overhaul one or more feeders. There are no instances yet of the heart of an ironbark pole decaying, though the heart of some of the mixed hardwoods which were accepted in lieu of ironbark may turn out to be not too sound. There are thousands of cases, of course, where even the sapwood shows no sign of decay, but this is too good to last much longer. Statistics Regarding Consumers. The following table shows the growth of consumers since supply commenced:

Curiously enough, the number of new consumers this year was the same as last year, which is, in itself, satisfactory. The percentage increase is, of course, lower, because of the higher total. It might be pointed out here that the percentage increase cannot be maintained at the same figure by securing each year the same number of new consumers; and that a declining figure in the last column is not necessarily a bad sign. The foregoing table can be further analysed as follows: —

1933 6,067 1,486 3,054 32,117 It will be seen that since 1927, there have never been less than 600 extensions to existing installation, and that in the year just ended, there were 806. As the year started with 9,350 consumers, we may therefore conclude that at least one in every twelve added to his installation. With regard to motors, 1553 have beeh added since 1927, while 204 were added in the last 12 months. The majority of these motors are fractional horsepower, but that does not matter, since their increase indictates that more and more uses continue to be found for electric power. With regard to ranges, 25 is not a large total for 12 months, and it would probably be found that high percentage of these was amongst the new consumers. There is, however, no cause for alarm. The small increase simply means that the board’s country clientele is disinclined to spend money on something for which it is already using a substitute.

Year centage ending Total units Total units March 31. generated units sold cost 1927 16,950,720 12,013,412 29.1 1923 21,183,210 14,968,107 29.4 1929 22,389,760 15,980,658 28.6 1930 23,331,520 16,762,536 28.2 1931 24,307,540 17,460,395 28.2 1932 23,971,960 17,320,983 27.3 1933 24,595,900 17,719,907 27.95

CO COO'OO w w w w re rc W N HOC CC 5 co Year ending. co Io co co co ro Record of o o co CO CH CO co lowest half-houi-OdOooo> peak demand. Q O (D P P P co co r-t- <-*- CO Ci 05 CH CH ►U S £ io io 05 io co CX) O Record of 03 CO 03 highest half-hour 03 &3 0? w peak demand. << << tr* pMM M tOM CO CH — 1 CO co 05 g Percentage variation between 4=» CH O CO CH cn highest and lowes'

Year ending Number of Years March 31. consumers Increase. 1926 5,547 — 1927 6,995 1,448 1928 8,031 1,036 1929 8,298 267 1930 8,784 486 1931 9,179 395 1932 9,350 171 1933 9,521 171

Year Total. ending ExtenRanges connected Mar.31. sions. Total Motors, load. 1927 1,556 880 1.501 18,550 1928 2,172 1,006 1,754 21,805 1929 2,900 1,123 2,070 24,012 1930 3,893 1,309 2,377 27,171 1931 4.604 1,423 2,691 29,719 1932 5,261 1,461 2,850 30,978