D.—l.

Lyttelton Diesel Station. After careful consideration was given to the suitability of several sites for the installation of a Diesel electric-power station, the location at Lyttelton was finally selected in the first week of November, 1930, and excavation was immediately started for the foundations of the units and the building. A high rate of progress has been maintained throughout construction by the General Branch of the Public Works Department. The first two of the four engines to be installed in the first stage of construction of this station were landed on the 3rd February, and erection of all equipment and accessories was pushed on with all speed in case of another shortage of water at the lake. A trial run of No. 2 unit was carried out on the 4th June. Survey and Easements. The following surveys were carried out during the year : Acheron River diversion, completion of Waitaki power-supply and Glenavy steel-tower line, second Timaru-Oamaru line, preliminary work in connection with the Oamaru-Dunedin line, location of site for Lyttelton Diesel station, and route of 11 kv. Lyttelton-Woolston line, steel tower crossing over the Waimakariri, location work at Timaru, Oamaru, and Glenavy substations. Negotiations with reference to easements covering the above routes were undertaken satisfactorily. Live-line Operation. Further progress has been carried out in this section with consequent reduction in interruptions to consumers. All insulators on the 11 kv. feeders were tested. Twenty-six poles were replaced under live-line conditions. The 33 kv. transmission-line to Banks Peninsula Power Board was overhauled, and all the 66 kv. insulators were tested between Lake Coleridge, Addington, and Timaru. Live-line methods were utilized in the installation of a 5,300 kv.a. transformer-bank at Oamaru Substation, thereby reducing the total period of interruption of supply to a few minutes. During the year a live-line cleaning-appliance was developed and tried out with satisfactory results on 66 kv. and 110 kv. insulators while alive. Transmission-lines. Owing to the absence of gales and heavy snowfalls, in the systematic cleaning and testing the line-insulators under live-line conditions, and cutting of trees likely to prove dangerous, very little line trouble was experienced during the year. Headworks and Power-house. Full opportunity was taken of the extremely low level of the lake to remove accumulations of shingle. To prevent the tendency for the water to shoal in the vicinity of No. 1 intake cylinder the original groyne was shortened by about 12 ft. and encased in concrete throughout its length. The western groyne was also concreted over the greater part of its length. No. 1 tunnel was inspected from end to end and found in very fair order. No. 2 tunnel was also partly drained for cleaning the screens at the intake, inspection of the cross-drive tunnel, and of the lake end of the tunnel. No. 3 and No. 6 lines have been painted. The annual report for year ending 1930 stated that seven out of the ten E.H.T. 4,000 kv.a. transformers had their low-tension coils replaced. The remaining three were dealt with this year. The reorganized lay-out of the whole of the 66 kv. equipment, which was commenced last year, has been completed, with the exception of the control wiring for the main oil circuit-breakers. Professor Hornell paid an unofficial visit to the power-house, lake, and headworks in October, 1930. Addington Substation. A 12,000 kv.a. bank of 66/11 kv. transformers which arrived in February was erected in March. The capacity of this substation will accordingly be increased from 29,000 kv.a. to 36,000 kv.a. A new circulating water-pump has been installed. A comprehensive lay-out of railway sidings was prepared and the first section to deal with equipment to and from the substation building itself was laid. Tests of the bearing value of the ground on the sites of the proposed test laboratory and steel structure were taken. No damage to any equipment was observed due to the severe earthquake of February last. No. 2 synchronous condenser, with a capacity of 10,000 kv.a. has arrived, and will be erected as soon as the construction on the two-bay extension of the substation building has been sufficiently advanced. Point Substation. The stick-operated single-phase isolating-switches have been replaced with triple-pole isolators. HORORATA. The whole system of earthing has been rearranged. Alterations involving increasing the number of 0.C.8.s from four to eight, replacing the stick-operated isolating-switches with gang-operated type, and replacing the independent-operated earthing-devices with a simpler method of grounding the lines was commenced in February. Ashburton. No structural alterations were carried out at this substation during the year.

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