BOROUGH ELECTRICAL UNDERTAKING.

Taranaki Herald, Volume LX, Issue 143762, 10 April 1912, Page 3

BOROUGH ELECTRICAL UNDERTAKING.

INTERESTING REPORT, At tho Borough Council meeting on Tuesday night Mr. H. Black, electrical engineer, presented the following report on the borough electrical undertaking:— Tho original scheme as recommended by Mr. Mestayer, and as accepted by tho council, comprised power station with a capacity of 90 K.W. transmission lino, substation and street lighting lines for 12 Arc and 78 Incandescent lamps. A panel was provided in tho substation, switchboard 1 for private lighting but no linos wore included in the contract.

Before the contract was completed a number of extras wore added included in which wore 50 extra street lamps and some private lighting, primary and secondary lines for private lighting. The works were opened and supply commenced on January 19, 1906, the total cost, including hydraulic works and part coat of tunnel being £14,445 to March 31 of that year. A few residents accepted) electric lighting on trust and. had 1 their premises wired ready for the opening but the majority waited until they saw: whether the street lighting was satisfactory. During the first year 126 consumers premises were connected, an average which has been fairly well maintained until latterly the increase has been more rapid—the number added during the year just ending being 230, making tho total to date 906. Before the end of 1906 the council, decided to install further and a second 21in water wain was laid, the power station building extended, a 90, K.W. generator and turbine put down' and a new switchboard installed at the substation. This set was started on regular load on December 28, 1907. As the line losses were becoming heavy the transmission line was duplicated, a pair of No. 0. 5.W.6. wires being added giving a capacity of nearly three times that of the original No. 4 S.W.G. line. This work was completed during December 1908. _ As there was a considerable demand for electric light outside the private lighting lines were extended and the first connections made on tho following dates: — Vogeltown, December, 1906. South Road to Breakwater, April, 1907.

Fitzroy, August, 1908. Very soon after the 90 K.W. set was installed it became evident that further machinery was necessary, and in July, 1903, a recommendation for a 48in pipjs lino and 200 K.W. generator was brought down. Although the demand for current was growing steadily the question was deferred from time to time and it was not until the end of 1910 that tenders were called for turbines and generators. In July, 1911, the tenders of Messrs. Turnbull and Jones, Ltd., was accepted for meters, Messrs. J. 0. Boving and Co. turbines, and the British Westingbouse Co.’s generators, switchboard and transformers. The new generator is designed to give 250 K.V.A. at 6000 volts, the intention being to transmit current at this voltage from the power house w> the substation or a point as near thereto as can be arranged with the Government. This contract ia part of a comprehensive scheme of extension which is proposed to be carried out as required. Taking them in order from the primary source of power, the Waiwakaiho River, the proposed works are as follows: — (1) Weir at intake to raise, the level of water, increase the velocity and compensate for lose of head during heavy loads. This work to bo carried out in the future when growth of supply demands it. No desigu has yet bejen considered of estimate prepared for this. (2) Forebay at pipe bead to provide settling pit with scour, large strainer rack, and outlets with valves, etc., for two 60iu power and one 15in water supply mains! This work is now in hand and consists of a chamber. 22 feet wide by 44 feet long and varying from, 23 feet to 28 feet in depth. The excavation for this work is nearly complete and a start should soon be made with the concrete. The ironwork is being carried out by day labour. Pipe line—This work consists of a linie of rivetted steel pipes, 704 feet in length, COin diameter at forebay reducing to 48in at powerhouse with connecting pipes for two 430 h.p. and ono 50 h.p. turbine. The work of excavating for these pipes is also being carried out by day labour and is well forward. Water to drive the existing machines is conveyed from the forebay by two lines of 21in spiral pipes. These are to be used in conjunction with the new main but provision' has . been made to replace those by a second COin to 48in line of pipes when required. _ Generating plant.—2so K.V.A. has been decided on as standard size of unit for the power station, the one on order being the first of tour. A second set to bo installed within twelve months and a third before the load reaches 400 kilowatts. . A 30 Iv.IV. exciter set is included in the present contract and provision has been mad© for a second similar set to act as a reserve, to be installed when the third alternator is put down. These exciter sets are designed to be driven cithet by motor or water turbino being direct counled bv means of friction clutches. The" first'alternator is now to hand, and tho turbines are just landing at Wellington. The switchboard now on order consists of 13 panels as follows: Four generators, two lines, two spares, one coupling and two motor high tension panels and two D.C- Exciter panels This board is therefore designed to serve the ultimate capacity of the power station when all the above units have been put down. Building extension. —This will be an addition of 28 feet making the length of the machine room 88ft 6in. There is also a bay at one side of the old machine room 49tt in length by 6ft 9in in depth to give room for the cell work of the high tension switchgear. The, additions to building are in reinforced concrete A 7i ton overhead travelling crane is being provided for handling the new machine. Later, it is proposed to raise the roof of the present machine room so that this crane can be used over the whole length. Tail race.—This present race is 6ft 3in in width but ret! need where passing under tho Dairy Company’s race to a 24in diameter pipe for a distance of about 50 feet whore it discharges into an open race. As this line of pipes was too small for present requirements a complete new tail race has been constructed lOin in width, with a minimum height of 6 feet and eight feet below the level of the existing race. This work is being carried out by day labour and should soon bo completed. Transmission line.—Current at present is being transmitted from the power station tp the substation in town at 2000 volts but as the line losses will be too heavy when tho load increases, it has .boon arranged,, _ae -already in-

Skated,, that tho voltage be raised to 6000. For this purpose special insulators will be required and other alterations made to tho lino and either especial cables' employed from John 'Street info town or step-down transformer installed at some convenient point and heavier cables used .to convoy current' from that point to the substation. Two transformers have been procured l for use at the power house. These will be used to reduce the voltage from tho new generators to 2000 volts until the line voltage is raised when they will he connected to the' existing machine to raise their- voltage to suit tho new generator and line voltage Two further transformers will be 'required to step down from 6000 to 2000 volts where the high voltage lino terminates in town, but these and the dine alterations are not immediately -required. Substation.—This building has for a long time being far too small for requirements, but owing to the fact that it had been built on the street and would have eventually to be removed additions have bedn delayed. This work would have been urged before hut for tho fact that tramway proposals were being considered and it was thought advisable, if possible, to combine lighting and tramway fjubstation in one building on the land acquired from the Railway Department for that purpose. A store large enough to hold all line material and sundries is wanted, a workshop, more office room and a special room foij stop-down transformers if installed in town. Some extra panels will bo required for the switchboard which also will require more room. At present the work of the department is carried out undiSr difficulties owing to want of room. The tramway substation will require room for switchboard, motor generators, boosters and battery,- and if possible, the car sheds and repair shops should he on the same site, so as to keep dowrt the cost of supervision as low as possible. Extra office room will also he 1 required in connection with the tram- ) ways and this should, if possible, bo at the car sheds where the men start and finish their work. It is only on account of these considerations that the extension of the substation has t not been ur ged' before, but some additional accommodation should ho provided l ai pearly as possible.