HYDRO-ELECTRIC POWER.

Hawke's Bay Tribune, Volume II, Issue 18, 4 January 1912, Page 3

HYDRO-ELECTRIC POWER.

THE LAKE COLERIDGE SCHEME. Wellington, Jam 3. Tend 'rs are to be invitml at one? for the supply of machinery for the Lake Co’eridge hydro-electric scheme and for tno pipe line whirl) will convey the water from the lake to the turbines. The Government recently called foi lenders for th? construction of a tunnel 7101) feet Jong to convey' the water from Lake Coleridgs through the hill to th? Rakaia river, but only one tender was received, and at the end of this weak contractors will be again invited to submit a price for the work. The tuni'el is to have a mean grade of 1 in 1000, and its top at the lake end will bo 12 feet below th? me.in lake level, its internal size is to be S feet by 8 feet in width with a semi-elliptic arch. It is to he lined throughout with co:ierete lining, New Zealand cement hemg .specified. The tunnel will convey li’.he water into th? outlet, works, when it will enter a pipe line 2700 feet levy leading to the turbines. The pipes are to be of varying thickness up to fiveeighths of an inch, according to pressure, which gradually increases as the power-house is approached, the. total fall of nearly 500 feet from the lake level to the turbine enabling the water to be delivered at a pressure of 21011) to the square inch. The test pressure for th? pipes ranges up to 4001 b to the square inch. At present only two pipe lines are specified!, but at some future date a third one will be installed, and the tunnel is to be mad: 1 big enough to cope with the supply then required. Th? initial machinery to laordered consists oi t !, i?’ Francis reactiifn turbines <>t 2U.0 brake horse-poitei eich developed at suo revolutions per minute, and one Pelton impulse turbine developing 225 horse -power to l:e used for driving the exciters. Ths main turbines will lie coupled direct to the generators, which are also to be ordered at once, and the total capacity of the plant will be 4500 kilowatts, representing 6000 horse-power. The power house and other structural features are' designed so as to easily extend the capacity to 12,000 horse-power, when six generators will be required. The specifications for the power lion e <'i< not yet ready, as the requirements <>l machinery v. ill first have to be settled, l-ut the general plan has been decided. In fact, so far as the electrical engineers’ department : s concerned, it has put the Coleridge schemes into final shape, and it is only necessary now foi machinery constructors to get to work. Tenders will not be opened for the next three months, and the specified time for delivery at Lyttelton is within ten months of acceptance. The machinery specified- is of a type in world-wide use, and there are no exclusive features in the design which would result in restricted tendering. Eight cottages lor power house employees are to lie constructed immediately, the tenders for this work closing on January 31st.