The inventions, researches and writings of Nikola Tesla / With special reference to his work in polyphase currents and high potential lighting

by Thomas Commerford Martin

Fig. 3.

Fig. 3a.

In Fig. 3 the armature has completed one quarter of one revolution. In this phase the current in coil C is a maximum, and of such direction as to produce the poles N S in Fig. 3a, whereas the current in coil C₁ is nil, this coil being at its neutral position. The poles N S in Fig. 3a are thus shifted one quarter of the circumference of the ring.

Fig. 4.

Fig. 4a.

Fig. 4 shows the coils C C in a still more advanced position, the armature having completed three-eighths of one revolution. At that moment the coil C still generates a current of the same direction as before, but of less strength, producing the comparatively weaker poles n s in Fig. 4a. The current in the coil C₁ is of the same strength, but opposite direction. Its effect is, therefore, to produce upon the ring the poles n₁ s₁, as indicated, and a polarity, N S, results, the poles now being shifted three-eighths of the periphery of the ring.