[D8534H], Letter from Alfred Montamat to Thomas Alva Edison, April 18th, 1885


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[D8534H], Letter from Alfred Montamat to Thomas Alva Edison, April 18th, 1885

Editor's Notes

I bring the following to your attention to get your opinion and instructions. ##In the month of January last year, we put up a plant in the Cardenas[?] Sugar Refinery--Dynamo #78 was put up with a B bobin. We had a great deal of trouble with it, the bobin used to get very hot after running one hour--after several trials we changed it for an A plant. It worked tolerably but never to my entire satisfaction. ##Two weeks ago I sold them a new bobin (the old one wanted a new commutator). The new one gave trouble from the beginning. It heated and sparked, and they had to stop several times during the night. It worked so for about 8 days and then got burned. I went to see it and found that the bobin was too big for the dynamo and it rubbed against the field magnets. ##I measured carefully the diameter of the space between the field magnets where the bobin revolves and found it was about 1/4 inch smaller than in other dynamos. I attributed to this the trouble we had from the beginning. If I am not mistaken, there must be a certain space between the bobin and the field magnets. If it is reduced, the electromotive force will be increased I nthe ratio of the square of the distance, the resistance remaining the same. There will be more amperes in the machine, causing heat in the bobin. Although all the resistance was put in the top[?], it was unable to reduce the EMF. This is the way I explain it--will you tell me if I am right and correct me if I am wrong? ##Shall I have the electromagents of Dynamo #78 turned on the lathe so a sto make the space as large as in the other 3 dynamos? ##I thought that all the Z Dynamos were built exactly of the same size and that all the Z bobins were also alike, and that they could be used with any Z Dynamo indistinctly. ##All the other plants have been working without trouble and their owners are perfectly satisfied.




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