D.—l.

Mangahao-Waikaremoana System. With the growth of load in the Hutt Valley area the 11,000-volt supply-lines from Khandallah were becoming inadequate for the supply to the district, so it was decided to put in a new 110 kv. substation at Melling with a 110 kv. supply-line from Khandallah, which will ultimately be extended to Masterton Substation to give an alternative 110 kv. supply-line to Khandallah. During the year additional transformer-capacity was ordered for some of the larger substations to provide for the estimated growth of load. In connection wth the extension of the system from Wanganui to New Plymouth with substations at Hawera, Stratford, and New Plymouth, further design work was carried -out. Wiring and phasing diagrams for the main line protective relay equipment were prepared and transmission calculations for the system were carried out. Bunnythorpe. —Drawings and specifications were prepared for the reconstruction and extension of the substation building. A foundation drawing was prepared for the capacitor. Melling. —The layout drawing of the site and drawings of the 11 kv. and 110 kv. switch-gear for tendering purposes were prepared. The drawings and specifications for the substation-building contract were prepared. A traverser-truck for handling the transformers and a turntable were designed, and a foundation drawing was prepared for the turntable and transformer-banks. The following design work was also carried out for this system :— Khandallah. —Preliminary layout 110 kv. switch-gear extensions ; layout of temporary switch - gear for 110 kv. line to Melling ; layout of proposed 110 kv. city substation ; foundations for capacitors. Napier. —Foundations for capacitor. Hawera. —Drawings for substation-building contract; preliminary layout of switch-room. Hawera, Stratford, and New Plymouth. —Layout of sites for construction purposes. Hawera and Stratford. —Design of traverser-trucks and turntables. Arapuni-Hobahoka System. The Grand Junction steam plant was re-erected at Huntly, and in this connection designs and specifications were prepared for a 50 ft. steel chimney and foundations for same. Hamilton and Bombay. —Preliminary layout drawings were prepared for the extensions to the steelwork and switch-gear to provide for additional lines, transformer-capacity, and switching and relay equipment. Arapuni.—k drawing was prepared for the temporary end-wall supports. Waitaki Power Development. The design of the power-house and main units was outlined a year ago, but much detail work remained to be dealt with during this year. The Napier earthquake led to investigation of resistance to earthquake stresses. The dimensions of the power-house are so great that conditions might be more severe than for a smaller building. Consequently, it was decided to provide against a horizontal acceleration of g, corresponding to an earthquake of intensity about 8| on the Rossi-Forel scale. These considerations have amounted almost to redesigning the power-house, retaining the general arrangement, but increasing the strength and stability to an extent that might not have appeared to be justified before the Napier earthquake. Architectural features have been reduced to a minimum overhang, diagonal bracing has been introduced in walls and some openings have been closed with reinforced concrete panels. The penstock and scroll cases of the turbines had already been rechecked on a conservative basis, and any possible sources of weakness dealt with. The stability of the building has been increased by eliminating stair-wells from the lower part of the annexe, and by constructing part of the scroll cases of the three future units, as well as by a wall on the intake side of the structure and buttress piers between the draught-tube outlets. In addition to the design being checked over and revised as described above, much detail work has been shown on drawings, notably for turbine- and generator-floor foundations, cable-shelves, piping systems, and auxiliary units, and for testing-apparatus, the latter being of a recent design, which gives remarkably accurate results. Foundation drawings were prepared for the outdoor switch-gear and steelwork for the powerstation, which also showed the layout of traverser-trucks and turntables. Transmission-lines. Waitaki-Glenavy 110 kv. Steel-tower Line. —Drawings have been prepared showing location of towers on route also assembly drawings of insulators. Timaru-Oamaru Line Duplication. —For a distance of two miles south of Timaru Substation it was decided to install double-circuit steel towers to carry both the existing and the new circuits, thereby causing less obstruction to the property on route than two separate wood-pole lines. Wanganui-Stratford 110 kv. Line. —Route plans have been prepared showing location of woodpole supports, also detail drawings of structures. A.rapuni-Edgecumbe 110 kv. Line. —Only part of this line was dealt with, supports being located on route-plans, also consideration was given to a special crossing over Lake Roto-iti which was deemed advisable in order to avoid sulphur springs in the Tikitere district. It has been found that copper conductors are badly affected by sulphur fumes. Arapuni-Stratford 110 kv. Line. —Between Taumarunui and Stratford the projected line passes over difficult country with steep papa ridges, and preliminary tests of the holding-power of anchorage in papa have been made. A light type of steel tower has been decided upon for this part of the line. Khandallah-Melling Line. —Various drawings and conductor sag and tension tables have been supplied for use on the erection of tnis line. Waikaremoana-Naqrier Line. —At one point on this line damage was caused by the earthquake in February and occasioned a certain amount of work in connection with the temporary measures for repairing the line also for the deviation finally decided upon for the permanent repair.

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