POLYPHASE CURRENTS.

59

through this motor it divides between its two energizing-circuits.The higher self-induction of one circuit produces a greater re-tardation or lag in the current therein than in the other. Thedifference of phase between the two currents efEects the rotationor shifting of the points of maximum magnetic effect that secures

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Figs. 42, 48’ and 44.

the rotation of the armature. In certain respects this plan of in-cluding both armature and field coils in circuit is a marked im-provement. Such a motor has a good torque at starting; yet ithas also considerable tendency to synchronism, owing to the fact