[NM021AAE], Technical Note, Thomas Alva Edison, September 5th, 1887


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[NM021AAE], Technical Note, Thomas Alva Edison, September 5th, 1887

Editor's Notes

Dyer-- Patent-- [drawing] Improvements in methods of indicating electric pressure in Central Eelectri Light stations= The invention consists in the employment of a standard battery giving the same electromotive force as that required at the ends of the feedders combined with several sets of pressure or return wires multiple arcd across such battery through galvanometers A B C D The battery so connected that it gives a contrary electromotive force to that due the Dynamo so that when the pressue on the pressure wires is 100 volts positive the standard battery will give 100 volts N & hence no current will pass through the glavanometers A B C D & they will stand at Zero indicating that the pressure at the ends of the feeders K M is correct, but if the load on the mains N decreases on one of the feeders & not in the other--and rises to say 101 volts; then there will be a current due to a potential diffusion of one volt & this will deflect the indicator it may then be brought back to zero by means of the feeder regulator X X' a Resistance G is placed around the battery to keep it in good action by this method the accuracy of the results do not depend on the indicating apparatus which need not be delicate and a deflection of several inches may be had due to a diference of one volt The maximum diference that is possibly obtainable in current is obtained by this method hence friction & other defects which render ordinary indicating apparatus so liable to incorrect reading owing principally to the necessity off great delicacy is obviated-- As all indicating apparatus is originally standardized by the battery if follows that a properly constructed battery is the best possible device for securing constant pressures in a station over a long period of time-- The battery I prefer to use is the ordinary gravity battery with moderately pure zinc & sulphate of copper Dyer make Broad clamis for this method--




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Thomas A. Edison Papers, School of Arts and Sciences, Rutgers University
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