Specifications

41
Fig. 4.6 gives the complete main winding diagram for a 2 pole 12 slots ac machine using
single layer half coil winding. In Fig. 4.6, R
S
, R
F
, B
S
, B
F
, Y
S
, and Y
F
indicate the starting and
finishing ends of RBY phases respectively.
Whole Coil Winding
The whole coil winding has one coil group per pole for each phase.
Total number of coils =
12
2
= 6; Coils per phase =
6
3
= 2; Number of coils of groups per
phase = 3 x 2 = 6
In this example, a single coil is a coil group in itself.
The winding should be connected between alternate North and South poles. First, R or A
phase winding is started. Starting with coil in slot 2, the start of R phase lies in slot 2, that of Y
phase in slot (2 + 4 = ) 6 and that of B phase in slot (6 + 4 = ) 10.
Fig.4.6 - 3 phase 2 pole single layer winding main winding main winding diagram (Half coil)
Fig. 4.7 - Coil group connections for whole coil winding
Fig. 4.7 gives the coil group connections for whole coil winding for each phases.