THIRD TURBINE

Poverty Bay Herald, Volume LXVI, Issue 19881, 7 March 1939, Page 4

THIRD TURBINE

NEW UNIT AT TUAI

HYDRO DEVELOPMENTS

PIPELINE IN PEACE

G EN ERATOP ASSEMIU A

(Herald Special KcpuiTcr)

Within a few weeks, tests will be carried out at Tuai . to ensure that the new pipeline, which will conduct water from the surge-chamber at Lake Kaitawa to the third generating unit in the Tuai power-house, is perfect in construction. The fabrication of the pipeline is now almost complete, and the installation of the new turbine is also well forward.

An Inspection of the hydro-electric plant at Tuai made yesterday by members of the Poverty Bay ElectricPower Board included views of the pipeline from different angles, and members of the party had their attention drawn to the contrast between results achieved by the electric-weld-ing method employed in its fabrication and those previously attained by the older method of rivclting.

Tire new work, they were informed, is expected to give better working results, and also has the advantage that it has cut the cost substantially.

The design of the new generating unit also bears tire impress of modernity, for though there is no great departure from the lines of the older units, the differences which to a layman seem insignificant carry much importance for the technical officers of the Public Works Department.

Built by Hoving’s, Limited, a British engineering company, the turbine and generator are sleek and impressive in appearance, and will deliver 20,000 horse-power when in commission. This will mean an addition of more than 50 per cent to the present production capacity of the powerhouse.

Relief and Emergencies

For the present there is not sufficient water available from Lake Kaitawa to permit of the three generating units operating simultaneously over any iong period. Until the flow of water from Waikaremoana can be controlled more efficiently, there will not be sufficient to exploit the full capacity of the Tuai installation. In the meantime', however, the third unit there will be available for relief and emergency purposes.

For over 10 years the older generating units, named Ruapani and Pukehore, as a compliment to the natives of the Waikaremoana area, have been running continuously at high speed, and it is obvious that with the load at its present level throughout the North Island, a breakdown of one of these units would have serious consequences. Hence the keenness of the Public Works Department to have the third generating unit installed as soon as possible. When the third unit is ready for work, each of the others will be taken out of service for overhaul in turn.

The new turbine and generator also will act; as a stand-by for the whole of the North Island system of interlocked electric-supply schemes. It has been evident for some time that the growing national load would produce peaks beyond the capacity of the Mangahao, Arapuni and Waikaremoana schemes.

No Waste Water at Kaitawa

Within the past week an official statement from the Public Works Department Indicated that steampower electrical plants in Wellington and Auckland were being used to reinforce the national system of the North Island at peak periods. The new unit at Tuai will help to meet peak demands in future, when water is available in the Lake Kaitawa storage basin.

The position with regard to Waikaremoana water is that barely sufficient is being trapped at the • Lake Kaitawa level to keep the two older generating units going. A few months ago, when the flow in the Waikaretaheke Stream began to fall off, the storage capacity at Lake Kaitawa was increased by raising the level of the dam across the stream. Yesterday there was not a drop escaping over the dam, and the flow into Lake Kaitawa was barely equal to the demands of generation. As things are, the flow will feed two generators continuously, and three'for short periods only.

Seepages From the Lake

One of the major works still to be undertaken by the department is the control of seepage from the main source of water at Waikaremoana. Practical exploratory work on this pioblem was begun in 1935, but was abandoned at the order of the Hon. R. Semple, the new Minister of Public Works. Mr. Semple considered that the methods, then loeing followed were not suited to the character of the ground in which tunnelling and boring were proceeding, on the lip of the lake near the Outlet.

Whether this work will be resumed, with newer methods, or whether some other scheme will be launched in the neighbourhood of the Outlet, it -s evident that means to control the flow of water in the Waikat etahelce must be found before the 1 uai powei installation can work at lull capacity. The urgent need for reinforcing further the Nortii Island network of production units suggests that it will not he long before departmental experts are again on the ground.