Lessons in practical electricity; principles, experiments, and arithmetical problems, an elementary text-book . ced into the magneticcircuit to lower its reluctance, is an electrical conductor also,and when rotated in the magnetic field will have currents in-duced in it, according to the principles of electromagnetic in-duction. A certainportion of theenergy driving thearmature is thusexpended in pro-ducing useless elec-tric currents, eddycurrents, ^f 292, inthe core, and whichdo not appear in theexternal circuit;this is termed eddy current loss, and con- .... , » .-. Fig. 334.—Eddy Currents i
Lessons in practical electricity; principles, experiments, and arithmetical problems, an elementary text-book . ced into the magneticcircuit to lower its reluctance, is an electrical conductor also,and when rotated in the magnetic field will have currents in-duced in it, according to the principles of electromagnetic in-duction. A certainportion of theenergy driving thearmature is thusexpended in pro-ducing useless elec-tric currents, eddycurrents, ^f 292, inthe core, and whichdo not appear in theexternal circuit;this is termed eddy current loss, and con- .... , » .-. Fig. 334.—Eddy Currents in the Armature Core. stitutes one ot the internal losses of a dynamo. A section of a solid armaturecore is illustrated in Fig. 334, and the direction of the in-duced eddy currents (found by Flemings Rule, ^| 278),indicated at this particular position of the armature core inthe course of its revolution. The heat produced by thesecurrents is chiefly at the outer surface of the core, wherethe eddies are strongest. The armature wires being woundon the surface will also be heated and their resistance in- 355. 356 PRACTICAL ELECTRICITY.
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