[D8737AAX1], Test Report, Henry E Walter, May 16th, 1887


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[D8737AAX1], Test Report, Henry E Walter, May 16th, 1887

Editor's Notes

"Test on Experimental '4' Armature with extra Resistance in each bar. (Experiment 8) ## The armature was run as a dynamo at 40 Amp. (1/2 load) and the brushes were set at the non-sparking point for this load. ## The load was then varied from 0 to 20, 40, 60 -- and 80 Amperes, and then down to 0 again. Then 20, 40, 60 & so on, the load being varied every 15 minutes. There was about as much sparking at 0 load as at 80 Amperes, but as the latter load it appeared to cut more. ## The temperature was about 75 degrees C after 3 1/2 hours with above variations of load, and that of the extra coils about 2 degrees hotter. Of course the speed of the extra coils was considerably greater than that of the Armature, and this would keep it cooler than the same resistance as that current under the speed of the wise on the Armature. ## The Armature was then ran as a motor, which it did just about as well as a dynamo, which is very good as a motor is nore susceptible to sparking than a dynamo. ## The general effect of the extra resistance is to make about as much spark with a variation of 40 Amp. At 1/2 the load as a regular '4' Armature would make under a variation of 15 Amp. or perhaps 20; so that the effect of the coils, is to frantically increase the neutral point 3 times. ## There is one thing however; that at 80 Amp. Load, even if the brushes be moved, there is always a slight spark, which it seems cannot be taken out. The resistance of each extra resistance loop is 1 1/2 times that of the Armatuers so that three together make 1/2 the resistance. ## And this with the Armature, and the resistance on the opposite side of the commutator make a total resistance, equal to twice that of the regular Armature." [page of drawn diagrams] Enclosure: "Edison Armature:-- ## A Regular #4 with loop of wire ([-].S.) between cup & torque .065 ohms__ would double to prevent induction Brush covers three which will make .022 ohms & .046 + 022 or just double ## [---] used is one length of #16 wire 23 feet (.058 ohms cold [--] .066 [---]___ Rubber tape to insulate ## Arm Resis .046__ total Resist .184__ 50 Block make .0034 each loop__ discharge into .022 = 6 times"



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