Specifications

60
Wave winding
Problem 3 : Develop the layout of a wave winding for a 3 phase having 4 pole ac machine and
24 slots. There are 2 coil sides per slot.
Solution : Coil groups per phase = 3 x 4 = 12 . Pole pitch = = = 6
Slots per pole per phase, m = = 2. Angle between adjacent slots, â =
180
24
4
= 30
0
.
There are 3 phase groups per pole, each comprising of 2 slots. The distribution of slots, of
phase sequence RYB or ABC, is shown in Table 4.9.
Table 4.9 Polar Groups
Back pitch,
Y
b
=
in terms of coil sides. The winding
pitch used for a 3 phase wave connected ac machine, Y = 12m. Therefore, Y = 12 x 2 = 24, The
front pitch, Y
f
= 24 –13 = 11 in terms of coil sides. 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
30
=) 5 and that of B or C phase in slot no.
(5 +
120
30
= ) 9. This makes the phase sequence RYB. Half of the winding will be in clockwise
and the remaining half of the winding will be in anticlockwise. Phase R starts with coil side 1 in
slot 1. Table 4.10 gives the winding table for R or A Phase.
Poles
Phase
N1 S1
R 1,2 7,8 13,14 19,20
Y 3,4 9,10 15,16 21,22
B 5,6 11,12 17,18 23,24
N2 S2
Table 4.10 Winding Table for R Phase
Following the procedure given in the Table 4.10, the winding for the other two phases can
be obtained.
Clockwise
S.No.
Top coil Side
(+Y
f
)
Bottom coil Side
(+Y
b
)
11 14
225 38
33 16
427 40
Anticlockwise
54 39
628 15
72 37
826 13
s
p
24
4
24
3x4