D.—l

98

This unit went into commercial operation on the 12th July, L 929. Some trouble is being experienced in the operation of the pressure-relief valves on both these machines as supplied, and modifications are under consideration. Outdoor Station. The erection of the 110 lev. and 50 kv. gear, reported nearly complete in last year's report, was completed, and final connections made. The 110 kv. 0.C.8.5, together with the isolating-switches, were then connected to their respective control cables and all connections checked. The seven 6,666 kv.a. 110 kv. transformers and 1,500 kv.a. 50 kv. transformers were dried out and placed in position on their foundations, oil and water connections being made to each tank. The station oil-purifying system, together with the fire storage tanks, were connected up, and the oil for the transformers and 0.C.8.s filtered ready for service. The 110 kv. equipment was energized on the 28th January. 1929, and the 50 kv. equipment on the 18th February, when the supply of power was given to Napier and Gisborne Substations respectively. Trouble was experienced with the 110 kv. isolating and air-break switch insulators breaking, and these insulators are now being replaced with insulators of another material. Provision has also been made to flood-light the outdoor structure, so as to facilitate inspection work at night. Several large slips on to the outdoor-station site destroyed portions of the station draining system. This has now been repaired, but it is quite probable that during the rainy season other slips will occur. The temporary power-station was finally taken out of service at the end of May, 1929, though prior to this a start was made to dismantle and re-erect the equipment in the main power-station. No. 5 unit was erected in the main power-station, and put into operation early in June, to supply current to the staff village and power-station. Work on the erection of the L.T. panels and No. 4 unit is being pushed on, and should be completed very shortly. General. Practically all the cable-work is now completed, and, excepting for the water-level indicators and controls for the gates at the surge-chamber, the installation of the power-station equipment is complete. General cleaning-up of the power-station and outdoor station yet remains to be done, also the grassing of the main-pipe-line slope. • Wairoa Loading-shed. All equipment has been removed from this shed, and the building is being left for the storing of equipment for the next development. Waikokopu Wharf Crane. This crane, now that the heavy lifts are over for the present scheme, has been painted, and all exposed parts covered with grease to prevent corrosion by rust. Transmission-lines. 110 kv. Transmission-lines. Tuai-Napier Section. —The work of constructing the main 110 kv. double-circuit line from Tuai to Napier, which was reported nearly complete at the end of June last year, was completed and ready for service in November, 1928, the first circuit being energized on the 28th January, 1929, when load was carried over same for the Napier district. Each circuit can be isolated for testing at three different points, a linesman being stationed at each switch and directly in touch with the power-station by telephone. A considerable amount of work is yet to be done in connection with getting patrol tracks in order, as the recent heavy rains in May last did a considerable amount of damage to same. One cage and two bridges have been erected to facilitate patrol. 50 kv. Transmission-lines. Tuai-Gisborne Section. —Work on this line was pushed ahead well, and by the end of December, 1928, this line was completed except for the erection of the isolating-switch at Tinoroto. When the construction of this line had only just started severe gales were experienced at the Tuai end of the line. As the result of this experience steps were taken to ensure that the line would withstand similar gales in the future. This line was placed into service on the 18th February, 1929, at 9 p.m., and since that date has given no trouble. Near the Gisborne end of the line it may be necessary to divert the line for about half a mile, as during the heavy rains in May last a considerable amount of the country moved. Work on the patrol tracks was also completed ; also the installation of cages across the Ruatikuri and Hangaroa Rivers. This line can be isolated for testing at three different points, a linesman being stationed at each switch and directly in touch with the power-station by telephone. Tuai-Wairoa Line. —When this line was taken over by the Department power was being supplied from the temporary power-station to the Wairoa Power Board at 11,000 volts, and, as this line was to be changed over to 50,000-volt service, this had to be done during the week-ends, so that the Power Board's service would be disturbed as little as possible. By the end of December this line had been converted, and ready for service at 50,000 volts. In case of trouble the line can be isolated at Mitchell's turn-off. This line was placed into operation at 50,000 volts on the Bth April, 1929.