The Electric Light.

Evening Star, Issue 7828, 8 February 1889, Page 4

The Electric Light.

ITS LATEST DEVELOPMENT. Thefollowingextraets from' The Engineer,' read by Mr E. G. Wright at the meeting of the Christchurch Gas Company, will be of interest: — In response to an invitation from the directors of the London Electric Supply Corporation, we ('The Engineer') availed ourselves of the opportunity of inspecting the buildings in the course of erection for their central station at Stowage wharf, Dcptford. The directors claim, and we think they are justified in making the assertion, that when completed their station will be the most remarkablo industrial establishment in the Metropolis: certainly it will be, when in full working order, the largest electric light station in existence. . . . The buildings at present

in course of erection comprise one boilerhouse and two engine-houßes, occupying a space of 210 ft by 195 ft, the height from the basement to the crown of the arched roof being close upon 100 ft, while the main walls reach 6ft in thickness. . . . The engines will run at sixty revolutions, and will drive, by means of forty sin cotton ropes, working over a 24ft drum, two Ferranti dynamos, each capable of supplying a current for 25,000 lights—by far the largest electrical generators that have as yet been constructed. ... Mr Ferranti made a number of experiments with different electro-motive forces, and finally settled upon 10,000 voltß as being the

most economical pressure at which to wdrk, having regard not only to the small loss in the mains, but also to the design of the transformers and dynamos which have to resist such a severe tension. It is needless to say that very special and novel designs were necessary for the apparatus used. . . . The second engine house is being arranged to take four direct-driving Ferranti patent dynamos of 10,000 indicated horsepower each. To give some idea of the size of these machines, it may be here stated that the shafts are 36in diameter in the centre, the armature about 45ft over all, and the weight of the whole machine, exclusive of the engine, some 500 tons. They will run at sixty revolutions with an electric motive force of 10,000 volts. . . . The electro-motive force of 10,000 volts may cause some surprise, but a number of careful experiments have shown that 10,000 volts is no more difficult to deal with than 2,400 volts if the right principles are employed in designing the machinery. ... Mr Ferranti, in designing the station and its details on the above principle, has a space of ground easily available, without crowding, for another 80,000 horse-power. This brings up the capacity of the three acres of ground, after everything has been provided for, to the enormous figure of 120,000 horsepower. These, again, will be, no doubt, startling figures, but anyone who will quietly consider the requirements of the metropolis for electric lighting will see that this is only a small step towards its fulfilment. . . . Before leaving the description of the buildings, we may state that they are being laid down on lines which will admit of an ultimate output of current for 2,000,000 lamps, and that tho present preliminary arrangements will, as already shown, admit of 250,000 lamps being run. ... It only remains to say that those concerned expect the resistance of the armatures will he less than 1 per cent, of the total electrical resistance to be overcome, and they believe that something under 3 per cent, will cover all losses of current over mains, leads, etc.