There are numerous kinds of two phase windings; the coils may be concentrated or distributed, half coil or whole coil, etc. Fig. 1,530 shows a two phase winding with four slots per pole, and fig. 1,533 one with six slots per pole.
Fig. 1,535.—Section of Triumph armature showing method of arranging the three phase winding.
Three Phase Armature Windings.—On the same general principle applicable to two phase windings, a three phase winding can be made from any single phase winding, by placing three identical single phase windings spaced out successively along the surface of the armature at intervals equal to one-third and two-thirds, respectively, of the double pole pitch, the unit in terms of which the spacing is expressed, being that pitch, which corresponds to one whole period.
Fig. 1,536.—Three phase winding with distributed coils—wound in four slots per pole per phase; diagram showing placement of the coils.
Fig. 1,537.—Treatment of coil ends in two phase, two range windings. In this arrangement straight out (B) and bent up (A) coils are used which are placed on the armature as is clearly shown in the illustration.
