Stationary steam engines, simple and compound; especially as adapted to light and power plants . r. By settingthem at intermediate points, the throw is made that is requir-ed to give an intermediate action of the valve, and thus thedistribution of steam is made to accord with the demandsof the work by such a variation of the ratios of expansionand of compression as is obtained by the link-motion, and,in this case, with the advantage in promptness of openingand of closure obtainable with a double-ported valve. Therange of action given in this engine is sufficient to permit a 132 STEAM ENGINES E
Stationary steam engines, simple and compound; especially as adapted to light and power plants . r. By settingthem at intermediate points, the throw is made that is requir-ed to give an intermediate action of the valve, and thus thedistribution of steam is made to accord with the demandsof the work by such a variation of the ratios of expansionand of compression as is obtained by the link-motion, and,in this case, with the advantage in promptness of openingand of closure obtainable with a double-ported valve. Therange of action given in this engine is sufficient to permit a 132 STEAM ENGINES EOR range of cut-off from o to about three-quarters stroke. Thelead remains unchanged, and the compression increases asthe ratio of expansion is increased. The springs of the governor are used in distribution of steam at the usual speed, and with fullload, is shown by the accompanying illustration, which is acopy of an indicator diagram taken from one of the enginesdriving the large dynamos at the Edison station in NewYork city. These engines are coupled directly to Diagram Taken at the Edison Station. and make with them 350 revolutions per minute. One ofthese engines was recently kept at work 17 days, makingover 8,400,000 revolutions without stopping, and then wasnot stopped because of any difficulty with the examined by the author, they were doing their worksteadily and smoothly, and were not appreciably affectedby the sudden changes of load produced by throwing onand off any considerable proportion of the lights on thecircuit. ELECTRIC LIGHTING PLANTS. 133 This engine illustrates well the perfection of regulationattainable by these positive motion valve-gears attached tothis form of governor, to which attention has already beencalled. At a trial of engines of this make made by theauthor, to satisfy himself in regard to their action undervarying load, 25, 50, and sometimes 60 Thomson-Houstonarc lights were thrown on or off, and the varia
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectsteamen, bookyear1902
