TransactionsPublished under the care of the General Secretary and the Treasurer . elbranches. The exciter voltage is equal to e = 2 -I mean = 2 Jp -trnax COS (X or substituting the value for -Pmax ?P, =2 f, m ^ I>,m^-^-±^ ^ cos a thus, Pe == j^ m sin ^ ^ -^ P cos a The potential curve Pmax sin or gives rise to cross currents inthe field winding. Since the magnetizing effects of these currentsneutralize each other, they need to be considered only in regardto their heating effect. Therefore, they must not be too order that the compounding of this type of generator may re-main as
TransactionsPublished under the care of the General Secretary and the Treasurer . elbranches. The exciter voltage is equal to e = 2 -I mean = 2 Jp -trnax COS (X or substituting the value for -Pmax ?P, =2 f, m ^ I>,m^-^-±^ ^ cos a thus, Pe == j^ m sin ^ ^ -^ P cos a The potential curve Pmax sin or gives rise to cross currents inthe field winding. Since the magnetizing effects of these currentsneutralize each other, they need to be considered only in regardto their heating effect. Therefore, they must not be too order that the compounding of this type of generator may re-main as exactly as possible at all displacements of phase andloads, it is desirable that the electric resistance for the cross cur-rents become equal to the resistance for the exciter currents. e). Commutator for asynchronous machines. If the commutator does not rotate in synchronism, but with acertain slip s, the mean potential curve rotates with a speed of ro-tation s n corresponding to this slip. In a three-phase windingconnected with the commutator, Fig. 60, a mean current will. Fig. 60. Rotor Winding ofA Compensated Three-Phase Motor With Hey-LAND Commutator. flow. This is three-phased and has the frequency Cs of the slipr If such a commutator is mounted on an asynchronous machine,the latter retains this property and works near synchronism with- ARNOLD AND LA COUR: COMMUTATION. 873 out running synchronously. The reactance x^ oi the rotor wind-ing for the mean current, which proceeds from the sinusoidalpotential curve, is naturally proportional to the slip s. The meanvoltage of phase of the rotor winding is — P^ = f, m sin *J-+^ ~ P. ~k ^ /). Conditions for sparJcless commutation. Let us consider the moment at which the brushes take the posi-tion relatively to the connected laminations indicated in Fig. 61.
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Keywords: ., bookcentury1900, bookdecade1900, bookidtr, booksubjectelectricity
