Specifications

56
180
0
corresponds to = = 12 slots.
There are 3 phase groups per pole, each comprising of 4 slots. The distribution of slots, of
phase sequence RYB or ABC, is shown in Table 4.6.
Table 4.6 Polar Groups
R 1 – 4 13 - 16
B 5 – 8 17 – 20
Y 9 – 12 20 - 24
Poles
Phase
North South
S.No. Top coil side (-Y
f
)
Bottom coil side (+Y
b
)
R or A phase per pole per phase
11 26
23 28
35 30
47 32
Y or B phase per pole per phase
517 42
619 44
721 46
823 48
B or C phase per pole per phase
933 10
10 35 12
11 37 14
12 39 16
The start of the phases must be displaced by 120
0
and so must be finishes. If the start of
R or A phase lies in slot no. 1, the start of Y or B phase must be in slot no. (1 +
120
15
=) 9 and
that of B or C phase in slot no. (9 +
120
15
= ) 17. This makes the phase sequence RYB or
ABC.
Full Pitch Winding : The top coil side in slot no. 1 is to be connected to bottom coil side in slot
no. (1 + 12 =) 13 or back pitch, Y
b
= 25, in terms of coil sides, ie., if slot no. 1 is at the beginning
of the first North Pole, N1, the slot no. 13 will be at the beginning of the first South Pole, S1.
The winding pitch, Y = +2 (progressive winding). The front pitch, Y
f
= Y
b
– Y = 25 – 2 = 23
in terms of coil sides. Table 4.7 gives the winding table for RYB or ABC Phases.
Table 4.7 Winding Table for RYB Phases
180
â
180
15