NORTH ISLAND POWER.

New Zealand Herald, Volume LXIX, Issue 21209, 15 June 1932, Page 11

NORTH ISLAND POWER.

LINKING CHIEF STATIONS.

GREAT CHAIN OF LINES. FORMING COMPLETE SYSTEM. [BY TELEGRAPH. — OWN CORRESPONDENT.] WELLINGTON. Tuesday. An important phase in the linking of the North Island hydro-electric power supply system by a great chain of transmission lines joining Arapuni in the north, Mangahao in the south and Waikaremoana in the east, has been entered upon by the Public Works Department.

A contract was lot some time ago for material for the sterl towers to carry the transmission lines across part of the gap between Stratford and Arapuni. When this has been bridged, the three powerful generating plants, whoso linking was visualised 15 years ago, will form part of one huge system. It is hoped to have the link completed by the winter of 1934 for the reason that by that time the plants at Mangahao and Waikaremoana will by then probably have reached their capacity. Spare Plant Available. There will be a certain amount of spare plant available at Arapuni at that time and it will be possible to transfer power from Arapuni to the south over the transmission lines which will join the three stations. Communication already exists between Mangahao and Waikaremoana, these two stations supplying power conjointly over the southern and eastern portion of the island. It is now the aim of the department's electrical engineers to link them with Arapuni.

Much work has been done in recent years as far as the erection of the transmission lines is concerned and the main power supply from the southern end stretches into Taranaki as far as Stratford. where it is to branch off to meet the Arapuni supply. From Arapuni the transmission lines will travel through Te Kuiti, Ohura and Whangamomona, finally joining the southern supply system at the present sub-station at Stratfoijd. The transmission lines have already been pushed about 20 miles south from the Arapuni .end and poles have been erected for about 40 miles. Steel towers, which were ordered recently, will be used to carry the high-voltage lines across tho rough country between Ohura and Whangamomona. Greater Security Assured. The plan also is to skirt the eastern districts between Waikaremoana and Arapuni through tho Rotorua area, but this work will come later. Efforts are being concentrated at present on the western link, which will be of great, value to I he North Island as a -whole, on account of the greater security it will give as far as a continuous power supply system is concerned.

The communication system will have general value for the whole island, for if one plant has to be closed for repairs or maintenance, the others will be able to continue a supply of power in either direction. Just how valuable the power supply link will be to the North Island is now illustrated in an official estimate of the amount that could have been saved to the Government had it been able to supply power to the North while Arapuni was closed for repairs. Had Mangahao and Waikaremoana been able to transmit power to the district served by Arapuni, the saving would have been £40.000 in one year, this amount representing the cost spent in purchasing power to make up the Arapuni deficiency. New Zealand was first presented with such a scheme in 1917 by Mr. E. Parry, who was then chief electrical engineer to the Public Works Department. In the following year he presented a comprehensive report to the then Minister of Public Works, Sir William Eraser. In his report he estimated that the total capital expenditure on the whole North Island scheme, would be about £7,503,000 and that it would take 10 years to carry it to completion. The Original Proposals.

The contemplated route of transmission lines was estimated at 1421 miles, with 29 primary sub-stations, and this vast network was to supply 44.000 square miles with adequate power. At that time it was stated that the Mangahao project was recognised as rather small for the needs of Wellington and Taranaki, and that other sources of power from the North would have to he tapped. The total cost of the transmission system v.as set down at nearly £1,800.000. It is 14 years since the report was written, although work on the plan has not been in progress right from that time. In any event, however, the original estimates of the total cost will have to be revised in the final analysis, as, for one thing, about £500,000 has been required to put Arapuni in order. At March 31, 1931, the capital outlay on the HorahoraArapuni plants totalled £3,939,122 and the capital outlay on the WaikaremoanaMangahao projects, £3.498,840, making a total of £7,437,962. The maximum load figures during that year, when Arapuni was working, were:—Arapuni, 49,520kw. and Waikaremoana-Mangahao, 44,66Gkw.