D—4

The inductive effects of short-circuits on our transmission lines in the communication circuits of the Post and Telegraph and New Zealand Railway Departments were studied, particularly for proposed lines. Negotiations regarding routing were started with these Departments. Miscellaneous work included a study of possible effects of various forms of centralized remote-control schemes ; conducting, on behalf of the British Electrical and Allied Industries Research Association, a questionnaire on performance of H.T. fuses on departmental and Power Supply Authority lines ; and research on the effectiveness of surge-arresters in power-transformer installations. (c) Transmission Section Contracts were placed in Great Britain for towers for the Stoke-Waimangaroa-Blackwater 66 kV. line and for the Bunnythrope-Haywards 220 kV. line. Specifications were drawn and tenders invited for steel towers and insulators for Whakamaru-Otahuhu and Whakamaru-Bunnythrope 220 kV. No. 2 lines. Close contact was maintained with the contractors for the supply of towers for the first 220 kV. lines from Whakamaru to Otahuhu and Bunnythrope. Lengthy negotiations were carried out to ensure adequate supplies of raw materials for the contract, which covers the supply of more than 9,000 tons of fabricated towers. Mechanical tests were carried out on one tower of each of the four types included in the contract; the results being satisfactory. Approximately 3,500 tons of tower parts have been delivered by the contractors and are held in the depot at Linton, but due to lack of certain sections no complete towers are available for erection, except the four test towers. Designs were completed of special piled and slab foundations for use in swamps on the WhakamaruOtahuhu 220 kV. line and details were supplied to districts for the execution of the work. Wire-stringing tensions for various loading conditions, and insulator deflections and mechanical loading of supports for various lines, were investigated and charts supplied for use in the field. Possible routes were investigated for the proposed 220 kV. lines from Roxburgh to Islington, with particular attention to snow conditions to be expected in the high country. There was little improvement in the material-supply position, which is still causing grave delays in the line-construction programme. Delays are particularly noticeable in the supply of steel fittings and of Australian hardwood poles and crossarms. REGULATIONS, LINES INSPECTION, ETC. The electric lines and works of twenty-six Electrical Supply Authorities were nspected. All the licences held by the Westport Borough Council were assigned to the Buller Electric-power Board, and those previously held by the Westport-Stockton Coal Co., Ltd., and Westport Coal Co., Ltd., were vested in the Minister of Mines. The Murchison County Council was granted a licence to extend operations, and the Ketetahi Timber Milling Co., Ltd., a licence to commence operations. Two small Supply Authorities had their licences revoked and new ones issued, and two other small Authorities were granted licences. The extension and redefinition of the boundaries of the Waitomo and Wairere Electric-power Districts was completed during the year.

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