MANGAHAO MOVES!

Shannon News, 12 September 1924, Page 3

MANGAHAO MOVES!

EIGHT THOUSAND HORSE ROWER IN ACTION Giant Generator Set in Motion TO RUN PERMANENTLY. Horowhenuas favourable Position (By Our Special Representative.) Mangtihao as a practical sCiieme pi iiydro-eiectrical generation came into definite oemg on Weunesday. At 3.15 p.m., v uie water was turned into die first or title huge 8000 n.p. turbines, which was thus started o% its life-work of de- \ doping %i'Giyer *Lind light to sappiy Uie requirements oi me Horowhenua district.

Wednesday’s act marks a concrete and important phase in the development ol the scheme. It is undeniable that, viewing the undertaking as a Whole, the turning on oi the water may ne relatively unimportant, hut it is an act which impresses from •its very obviousness. To this end every other phase oi the work which htfo occupied 4£ years oi strenuous endeavour has tended. To this .end the dams with their 44,000 tons oi reinforced concrete work, have been constructed under endless difficulties and disappointments. To this end have tunnels, surge chamber and pipe )ines been built. On the powerhouse at the' foot of the hill converged, as it were, all the hopes and aspirations oi every man’ who has held executive command on the Mangahao scheme, and yesterday’s consummation, ii it did not mark the end of their endeavours, has definitely indicated their reward. Mangahao is working— that is the all-important point. Tentatively perhaps-feeling its way gradually—trying its newly acquired wings, in title under-confi-dence of a new birth, but still working, definitely launched into the ranks of accepted things. THE DAMS FILLED. For practically a week—since Thursday last to be exact—the 'engineers at Mangahao have been working strenuously, but steadily—with a 40(fib pressure to the square inch no risks are taken—towards this end. On the preceding Monday the water had been turned into the Mangahao dam and during the next couple oi days flood gatts and tunnel gates on the Maiigaliao and Arapeti tunnels and. dams, had been tested under ail conditions. The Arapeti dam had been partly filled through turning the Tokoinaru stream into it, but on account oi a - defect in the working ol the gate into the No. 2 tunnel it was found necessary to empty most of this again. On Thursday morning everything was ready to test out the pipe-line which is the ultimate link between the Mangahao river, miles back in the rugged Tararua Gorge and the power house at Mangaore. At 9 a.m. on Thursday morning the gate blocking the entrance into No. 1 tunnel connecting the Mangahao, wit" the Mangaore d§m was opened and the water banked up in the Mangahao dam to 6ft above the level of the top of the tunnel, roared through in a six-foot flood to fill the Arapeti dam.

FIRST WATER ROARS INTO PIPE LINE.

When ,a. “News” representative arrived a t file pipe-line at 10 a.m. tne water was just beginning to liow into the pipes. Running alongside the pipe-hue on its 3700 u lengtn irom trie power-house tQ tlie surge chamber is a cable tramway, and nail' way up tills as the truck, slowly climbed towards tne surge chamber, there came a sudden, rusn of water in the pipe, plainly to be heard by those riding on the truck. It was the first water froin the Mangahao river finding its way towards the turbines! On arrival at the top our representative was directed by Mr G. P. Anderson*; the Engineer in charge of this particular portion Of the work, to a man hole in the top of the six-loot steel pipe. Inside, a yellow flood a loot deep rushed down the pipe at the rate oi 3000 gallons to the minute, the colour ol the water toeing due to the mud from the bottom of the concreted tunnel. Around the top oi the huge 80ft deep surge chamber was gathered every man employed on the wbrkls. The water was coming through from Mangahao and they watched with evident fascination as it rose siowly in the surge chamber to find fire level of the dams behind. DANGER OF AIR LOCKS. The uninitiated was soon to learn that the filling of the pipes was an exact process—something more than allowing the water .to flow in as fast as the pressure behind forced it. That way, Mr Anderson explained, lay ‘air-docks,” qr cushions of ah, in the pipes, with consequent danger oi -burst pipes. With Mr Anderson, our representative descended the 72 foot 6x5 concrete shaft leading down to behind the gates where they give outlet from the surge-chamber to the pipes. Standing on the steel ladder behind the huge iron. door, which, with file ?-inch steel rod by which it is raised, weighs over 4 tons, it was po&sible to gauge the flow of the water and its height in the surge chamber behind the door.

ALL POWERFUL-WATER. One inch-only from the floor the door was raised, but in the dim light which filtered* from the head of the shaft 72ft above and the light* of an electric torch, the water could be seen shooting out in a *hlid stream Iron

■ beneath the door and forced by the weight behind it in two streams Horn the sides of the door. One inen-irom tiie floor and a flow of two to three thousand gallons to the minutel TUe reader can imagine the flow had the door been raised to its full Bit. Even this was too last, however. A shouted command and the door shut I slowly down. Too lar—the water is | shut off completely. Then, as it was raised again, it was possible to gain an Idea of the pressure exerted ny the weight of water in the surge chamber, where it had by this time I reached the full height of the door, and in the tunnels beyond. As the (door rose again in response to ant other signal, a solid stream of wa- ) ter shot out a full five feot from beneath the door, the force carrying it this distance before it touched bottom.

TESTING OUT THE PIPE LINE. The filling of the pipeline was completed by 3.31) p.m., but a considerable amount of testing-out nad to be done before the water could he turned on to the turbines’. Valves had fo be tested, several leaks which developed in the pipes under the enormous pressure had to be repaired, and although a five-minute run was given to the turbine on Thursday last, it was not until Wednesday that everything was in readiness to definitely couple up. TUNING UP THE GENERATOR. When our representative arrived at (he power house Wednesday afternoon the big four-ton 8000 h.p. generator which wafe to he coupled up, bore a'n obviously “cleared lor action” appearance. Mechanics were busy giving the finishing touches to the huge ton weight bearing-cap which holds the shaft on which the Pelton wheel and alternating current generator, revolve. The cap is hoisted into position, the 40 ton travelling crane making short work of it and a tighteningof bolts leaves everything ready for the final act. A final inspection by-Mr Blackwood, the engineer in charge ol the. power-house, and Mr Dinnie, Engineer-in-chief lor the whole Mangahao scheme, and at 3.15 all was complete. WATER ADMITTED TO TURBINE. Temporarily work in the powerhouse was suspended, a ring of men gathered round the turbine, whilst the rails guarding the sides of the two central floors were lined *vitli faces. Then one of the Staff slowly turned the screw operating the needle valve, which lets tiie allpowerful water Into the Pelton wheel. For a moment nothing happened. The Pelton wheel being cased in, nothing was to be seen there but, slowly at first and then with an irresistible rush, the motor in the big generator began to revolve. It gathered speed until it was revolving at the rate oi 2UO revolutiorfcs to the minute, and a mighty rushing sound as of a storm in the tree-tops proclaimed its velocity. Other sound there was none, smoothly, without effort and without noise, tiie huge mass of m.etai revolved, so perfectly balanced, turning in its bearings in a film of oil, that it is said that when the water is turned off it will run oi its own .volition ior a full half hour, and that one man can turn .it by hand.

TURBINE NOW RUNNING CONTINUOUSLY.

The tulrbijne which was connected yesterday, wifi be run lor the next week Qr . a fortnight at half velocity—some 200 instead oi the lull 375 revolutions to the 'minute, for the purpose of drying out the coil's ou the generator. -

HOROWHENUA LINKED UP

At the 1 end ol' that time current will probably be available to tne Horowhenua Power District, ike transmission lines 'for which wore yesterday attached to the. insuhnors at the power house in anticipation of the event. Incidentally it is stated that Horowhenua should have the most, satisfactory supply ol • any obtained irom file power house. For transmission purposes it is necessary, in .order to avoid loss in transmission over long distances to laise the voltage from the il,ooo at which it is generated, to as much as 110,000 volts. In ail cases where trouble has occurred at the Lake Coleridge scheme it has been on ihese high tension cabie-s and not on the lower 11,000 volt lines. Horowhenuabeing on the spot as it were, will be served direct with the 11,000 voltage and should therefore be free from service interruptions. The turbine connected yesterday will be the only one run for some time to come. This one machine 1 will be more than sufficient to supply the requirements of Horowhenua, the only Rower Board, so far, ready to take “the juice” and the other turbines, will be brought into running between now and next- February, when Mangahao, a)s an undertaking, is expected to be completed.