Power to Ohakune from an early start

Waimarino Bulletin, Volume 6, Issue 265, 29 November 1988, Page 8

Power to Ohakune from an early start

The Electricity Department played an important part in the development of not only the Borough of Ohakune, but also of its surrounding district, particularly the south and south-westerly areas.

The courage and enterprise of the poineers of the Town Board and later of the Borough Council, in deciding that electricity should be provided so early in the development of the settlement is indicative of the energy and

vigour with which all problems and needs of the day were attacked, as instanced by the fact that in 1912, when reports and estimates were being obtained by the Council on the proposal for hydroelectric generation and

distribution, very few places in New Zealand outside the main cities were receiving electric supply. The first Town Board had taken office in 1908 and the town's constitution as a borough followed in 1911. Two Choices Two schemes were reported upon, both estimated to provide approximately 400 H.P. and both using the Mangawhero River,

but with one significant difference. One was a high pressure proposal with 10,200 ft. (3139m) long pipe line of sufficient capacity to provide also for a water supply

to the young borough. The cost of the headworks and pipe line was to be shared equally under the two headings with a complete cost of £8,000 each for electricity and water. The alternative proposal submitted by a different consultant, was for a low pressure scheme not providing a water supply. The estimated cost of this scheme was £200 less than the former. This alternative proposal was accepted on the casting vote of the Chairman, thus initiating a power shortage that was to last 46 years and have a profound influence in retarding the development of the Electricity Department and of the township itself. A material discrepancy in the two reports was apparently unnoticed when the decision to adopt the low pressure scheme was made: The consultants for the high pressure scheme had based their estimated minimum capac-

ity of 400 H.P. on an observed river flow of 11 cusecs while the consultants for the low pressure scheme estimated the same minimum output without storage on a m u c h lower pressure. In short, a minimum river flow of 11 cusecs with the head available of 39.6 ft and average efficiency for turbines, represented that an output of not more than 30 H.P. was available from the Mangawhero River but with the clearance of the bush and faster runoff from the catchment in latter years flows as small as 8.5 cusecs were noted. 136 Consumers And so in the latter part of 1914, the supply of electricity t o 136 consumers in the Borough of Ohakune commenced. A standard 3 phase 415-230 volt A.C. 50 cycle supply was adopted, with generation from two Boving 120 H.P. turbines direct coupled to Westinghouse 3 phase, 2400 volt alternators. Provision had been made for the installation of a further unit if and when necessary. Power charges were: Lighting one shilling and power four pence per unit with minimums of five shillings each per month. The first Engineer was the late Mr W.A. Waters who had installed the plant and reticulation for the contractors. Only the inner area of the Borough was then reticulated, there

being 5-10 K.V.A. 2400V-400-230V transformers for supply to consumers. H.T. and neutral were bare conductors and phase wires were braided, with some in perfect condition fifty years later. The plant was at first continuously attended, being shut down for meggering of lines and alternators each Sunday from 9am to 5pm. Movies race water As the plant commenced to operate at the beginning of the low flow period Octo-ber-May, shortage o f power was experienced even with the very small demands then being registered. Early powerhouse log books contain many references to these difficulties and the methods adopted in combatting them; some drastic but effectual. The major evening load comprised two cinema theatres both of which used a seven and a half H.P. motor to drive D.C. generators for their 80 amp arc supply. These motors were controlled b y compensator starters with no volt release. The water supply flume was 800 yards long and five feet by four feet in section, so that it was possible to draw on the somewhat considerable storage represented by this. The level in the flume was watched carefully and it became a race against time, which would go out first, the pictures or From page 13

OUR HISTORY

Power to Ohakune from an early start

From page 8 the water. If it was seen that it would be the latter, then the circuit breaker was opened momentarily and this break in supply caused the no volt release on the picture motor starters to operate thus cutting off the motors. The proprietors then had to couple a belt to a standby engine and thus finish their programmes and this pro-

cedure seems to have been accepted quitephilosophically by all concerned. Stop that! It was noted that on one occasion one proprietor thus cut off, and with only a small amount of film left to complete the programme, with great daring re-started his

motor, hoping it would not be observed. He was unlucky and the log records that the circuit breaker was immediately tripped and left out for five minutes as a warning to all and sundry that "you can't do that there 'ere". Mr Waters did not remain in his position

for long and was succeeded by Mr J.W. Downie in 1915 and he in turn by Mr T.G. Burrell in 1917. The load was increasing slowly and the first extension to reticulation to Station Road was carried out. Water Storage Mr Burrell had reported on the possibility of using the crater lake in the bush just beyond Ohakune for storage or alternatively, installing one turbine higher up the river so that the water could be used twice. The total load was

much less than the output of one unit, viz: 60 K.V.A. It was finally decided to install a suction gas plant to drive on to No. 2 turbine shaft. A Cambridge producer and a horizontal single cylinder Tangye engine were installed, belt driven. This was by no means satisfactory for several reasons, the principal reason being the time required to raise gas in the producer from cold. Mr Burrell resigned in 1922 and Mr J.P. Cottier succeeded him

at a period when there was considerable agitation for supply to be extended to cover the whole of the Borough, Rangataua and Makaranui. These areas were canvassed and an estimate of cost prepared. The Raetihi Borough Council applied for and was granted an area not only including Makaranui but territory North, South and East of Ohakune. A map of the two areas at that time showed Raetihi having an area similar in shape to a boot, while Ohakune

had the tongue of the boot. Extension of Ohakune's area necessitated extension of generating capacity and this could only be achieved by a high pressure installation or the installation of an engine using gas, oil or steam. A 180 B.H.P. semi-diesel engine, direct coupled to a 141 K.V.A. 2400 volt alternator and exciter was decided upon, and the 2400 volt primary reticulation was extended via Shannon and Ruapehu Streets to Rangataua township. All this work was financed by way of a £7,500 loan proposal and was engineered and executed under the direction of Mr J.P. Cottier. Load commenced to grow at an accelerated rate and the semidiesel was being used more and more, not only during periods of hydro deficiency but also to cope with peaks. Raetihi negotiations Negotiations were commenced with the Raetihi Borough Council in 1929 for supply from their system to meet deficiencies at Ohakune, Mr Cottier leaving before finality was reached and F. Woodward being appointed Engineer. This story to be continued next issue