For instance: If the six pole monotooth, single phase winding, shown in fig. 1,527, be thus duplicated, the result will be the one slot two-phase winding shown in fig. 1,529, which will have twelve slots, and will require four slip rings, or two rings for each phase.
By connecting up the two windings in series, the machines could be used as a single phase, with an increase of voltage in the ratio of 1.41 to 1.
Fig. 1,533.—Two phase winding in three slots per pole per phase. The coils of each phase are of the partially distributed type, each coil being made up of three sections as shown. The direction of winding is alternately reversed.
Fig. 1,534.—Section of two phase winding showing shaping of the coil ends. Every other coil is flat, while the alternates have their ends bent down as shown. With respect to the shaping of the coil ends, it is called a two range winding.
Ques. How must the coils be constructed for two phase windings?
Ans. They must be made of two different shapes, one bent up out of the way of the other, as in fig. 1,534.