Figure 7-60.--Three-phase, four-pole, series-wye winding.
All the arrows on the line leads (fig. 7-60) indicate
current in the same direction toward the center of the
wye. Actually, the current at one instant may enter the
phase A lead and leave by the other two leads. At the
next instant, current may enter through phases A and B
and leave by phase C (fig. 7-61). At any instant, current
is flowing into and leaving the wye by at least one lead.
This illustrates how a four-pole motor or generator
actually functions. In rewinding, however, having the
current going in at all phases and ending at the internal
star connection (figs. 7-60 and 7-61) is best for bench
testing the stator.
The series-wye connection (figs. 7-60 and 7-61) is
employed in ac machines designed to operate at a
comparative y high voltage. Machines that require a
Figure 7-61.--Three-phase, four-pole, series-wye winding
showing the four poles.
relatively high current usually are wound in a multiple
or parallel arrangement.