groups 1 and 4 are placed in parallel with pole-phase

groups 10 and 7, resulting in an increase in the

current-carrying capacity. The voltage drop across that

To connect the machine for three-phase, four-pole,

phase remains the same without changing the number

parallel-wye operation, use the diagram shown in figure

7-62 with the same number of pole-phase groups and

of pole-phase groups.

the same assumed directions of current flow through the

groups as in the series-wye connection the pole-phase

groups of the three phases must be connected so that the

current flows through the various groups in the

The same machine connected for three-phase,

directions indicated to obtain alternate north and south

four-pole, series-delta operation is illustrated in figure

poles. Again, connect the battery, as previously

described, by connecting A, B, and C start phase to one

7-63. The same pole-phase group numbers are allotted

side of the battery; and A, B, and C finish phases to the

to the same phase windings, and the directions of current

other side. Again the 12 compass polarities should be

flow through the groups are the same as for the other

indicated in one revolution of the stator.

examples.

The only difference between the parallel-wye

Note the difference in the series-wye winding (fig.

winding (fig. 7-62) and the series-wye winding (fig.

7-60) and the series-delta winding (fig. 7-63). In the

7-60) is the four pole-phase groups, which were

series-delta winding, the three phases are connected so

originally in series in any one of the phases, but are now

that they form a delta, and the external connections are

split into two parallel paths of two pole-phase groups.

made at the three corners of the delta.

In phase A the same coil groups are used, but pole-phase