Lessons in practical electricity; principles, experiments, and arithmetical problems; over four hundred illustrations; an elementary text book (1909)
Swoope, C. Walton (Coates Walton), d. 1901 · New York, D. Van Nostrand company · leaf 384
351.—The Act of Commutation of anArmature Coil. At the instant shown coil B is short-circuited bythe brush. * Suppose that the brush in Fig. 351 had been made of copper instead of carbon, as isgenerally used, its resistance would have been less and a greater current would havecirculated around the… … point, and the E. M. F. in them is higher, causing a greatercurrent to rise for the instant, which is noticed by an in-crease in sparking at the brushes. To find the neutral, ornon-sparking point of a dynamo, when it is running, the brushesare rocked backward or forward until the sparking…
Electricity · Magnetism
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