[D8737AAR], Test Report, Henry E Walter, April 25th, 1887


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[D8737AAR], Test Report, Henry E Walter, April 25th, 1887

Editor's Notes

"Heat tests on armature cores:-- ## Test on '12' armature core with discs insulated with Mr. Edison's solution. This is the second test made, and this time it was run with a covering of the loose texture felt, but as will be seen this did not make much difference in the increase of temperature, tho' this can be accounted for almost entirely by allowing for the radiating effect of the armature or the rate of decrease of temperature of the armature when stopped. Run 8 hours. [-] Mins. Volts on field 96.5 average 1200 speed. The results of the test will be give in a table later on. (Test made April 15th.) ## Test on a '16' armature core with this discs .0065 thick. Run 3 hours, mean volts & speed 91 (should be 90 V.) & 1000 revs. Armature covered with close texture felt. Test made April 19th. Armature 1/1[-] larger than usual. ## Test on '16' armature with regular plates (.0125") Run 8 hours and 5 Mins. Mean volts and Speed 90 and 995. Armature 1/16" larger than usual. ## Some of the armatures have been run for half an hour after test without field to see what rate of cooling they had under speed. The following is a table giving data of last 8 tests on iron cores including all but the very first made in New York. ## The summary is that there seems to be a doubt new as to whether the armature with the iron sleeve did increase much beyond a regular armature. The actual rise of temperature of the armature showed an increase of 25% more heat than a regular armature, but as far as can be seen from rough figures of decrease of temperature after it had been stopped, it did not radiate heat nearly as quickly as the other. I think it will be well to make another test now that I know how much difference the covering has on the heat and how the (nearly) absolute increase can be arrived at by running the armature in no field and getting its rate of cooling. ## There seems to be no difference of increase between the regular armature and the one with a bronze sleeve, tho' this latter seemed to cool off a good deal thro' the shaft, as it cooled off more rapidly from inside the best hold than it did at the surface. The difference between the thin and the thick plates is nearly 50%, that is, the this plates heat about 55% of the regular, but the total increase of the this plates is so small, that it is probable the per centage is less. It should be 25% only."



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