Theory and calculation of alternating current phenomena . ttle in amachine of low armature reaction and high self-induction, as ahigh-frequency unitooth alternator, 193. Graphically, the internal reactions of the alternating-current generator can be represented as follows: Let the impressed , or field excitation, Fo, be repre-sented by the vector OFo, in Fig. 139, chosen for convenienceas vertical axis. Let the armature current, I, be represented byvector 01. This current, /, gives armature reaction Fi = nl,where ?i = number of effective turns of the armature, and is repre-sented by the
Theory and calculation of alternating current phenomena . ttle in amachine of low armature reaction and high self-induction, as ahigh-frequency unitooth alternator, 193. Graphically, the internal reactions of the alternating-current generator can be represented as follows: Let the impressed , or field excitation, Fo, be repre-sented by the vector OFo, in Fig. 139, chosen for convenienceas vertical axis. Let the armature current, I, be represented byvector 01. This current, /, gives armature reaction Fi = nl,where ?i = number of effective turns of the armature, and is repre-sented by the vector, OFi, with the two quadrature components, 274 ALTERNATING-CURRENT PHENOMENA OFi, in line with the field , Oh\—and usually oppositethereto—and OF, in quadrature with OF^. OFo combined with OFi gives the resultant , OF, withthe quadrature components, OF = OFo — 0F\, and OF. The , OF, produces a magnetic flux, 0$, and this gener-ates an , OE2, in the armature circuit, 90° behind OF inphase, the virtual generated Fig. 139. The armature self-induction consumes an , OE3, 90°ahead of the current, thus, subtracted vectorially from OE2,gives the actual generated , OEi. The armature resistance, r, consumes an , OEi, in phasewith the current, which subtracts vectorially from the actualgenerated , and thus gives the terminal voltage, OE. 194. Analytically, these reactions are best calculated by thesymbolic method. ARMATURE REACTIONS OF ALTERNATORS 275 Let the impressed , or field-excitation, Fo, be chosen asthe imaginary axis, hence represented by ^ Fo = + jfo (1) Let / = u — ji2 = armature current. (2) The of the armature then is Fi =nl = nC/i - ji2) (3) where ji = number of effective armature turns, and the resultant then is F = Fo + Fi^ jifo - ni^) + mi. (4) If, then,(P = magnetic permeance of the structure, that is, magneticflux divided by the ampere-turns producing it, (P = ^, or, ^ =
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectelectriccurrentsalte
