Lessons in practical electricity; principles, experiments, and arithmetical problems, an elementary text-book . sis(page 308, Exp. 82). A por-tion of the energy required todrive the armature is thus ex-pended in heating the core anddoes not appear as useful elec-trical work. The heat so gen-erated also heats the copperwires wound upon the arma-ture core, increasing their resis-tance and the C2R loss, so thatstill more energy is wastedwhich does not appear as use-ful energy. This is calledhysteresis loss in a Armature current flowing from an armature circulates through
Lessons in practical electricity; principles, experiments, and arithmetical problems, an elementary text-book . sis(page 308, Exp. 82). A por-tion of the energy required todrive the armature is thus ex-pended in heating the core anddoes not appear as useful elec-trical work. The heat so gen-erated also heats the copperwires wound upon the arma-ture core, increasing their resis-tance and the C2R loss, so thatstill more energy is wastedwhich does not appear as use-ful energy. This is calledhysteresis loss in a Armature current flowing from an armature circulates through itsinternal windings, and produces magnetic poles in the arma-ture core which react upon the magnetic field and distort current to beflowing in the direc-tion indicated, fromthe armature windingsdepicted in Fig. 347,a N and a S-pole areproduced at diametri-cally opposite points,where the current en-ters and leaves thearmature by thebrushes, just as in thecase of the plain ironring C, of Fig. when this arma- Fig. 347.—Magnetic Field Produced by Current Circulating Through the Sr^tfSS Fig. 348.— Eeaction of the Armature FieldUpon That of the Field Magnets. ture is placed in its field and current flows from it, Fig. 348,its poles induce two poles in each of the field cores by mag-netic induction, with the polarities as indicated. ARMATURES. 363 One induced pole in each field core tends to strengthen thenumber of lines of force threading from the field to the arma-ture core, while the other induced pole tends to neutralizethe field magnetism or to produce neutral points in the field atthe opposite ends of a diameter. This will be more clearlyunderstood from Fig. 349, which rep-resents the resultant distorted mag-netic field produced by the cross-mag-netising effect of the armature uponthe field. The neutral points neartwo of the pole tips and the pointswhere the lines are crowded under theother two pole tips are shown by theaid of iron filings. In
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