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Scientific American Supplement, No. 392, July 7, 1883
The continuous current and the alternating current generators invented by Dr. J. Hopkinson and Dr. Alexander Muirhead are peculiarly interesting as being probably the first in which the bobbins of the armature were wound with copper ribbon and arranged on a disk armature much in the same way as was afterward done by Sir William Thomson and by Mr. Ferranti. In the Muirhead-Hopkinson machine the armature coils are attached to a soft iron ring, whereas in the Ferranti the iron core is dispensed with, and a gain of lightness in the armature or rotating part effected; this advantage is of considerable importance, though Messrs. Hopkinson and Muirhead can of course reduce the weight of this iron core to insignificant proportions. The armature is made by taking a pulley and encircling it with a rim of sheet-iron bands, each insulated from the other by asbestos paper. On one or both sides of the rim thus formed, radial slots are cut to admit radial coils of insulated copper wire or ribbon, so that they lie in planes parallel to the plane of the pulley. In the continuous current machine coils are placed on both sides of the iron rim and arranged alternately, that on the one side always covering the gap between two on the other side. In this way, when a coil on one side of the rim is at its "dead point" and yields its minimum of current, the corresponding coil on the other side is giving out its maximum. ......Buy Now (To Read More)
Ebook Number: 8742
Author: Various
Release Date: Aug 1, 2005
Format: eBook
Language: English
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