Specifications

32
From equation 3.18 the winding pitch, Y =
+ 2 = 2 (even integer)
From Fig. 3.9 or from equation 3.20, front pitch, Y
f
= 11 –2 = 9 or 13 – 2 = 11
(odd integer).
3.9 WAVE WINDING: When the finishing end of the first coil is connected to the starting end of
the next coil, as shown in Fig. 3.10, which starts from the next adjacent pole where the first coil
started is known as wave winding.
From Fig. 3.10, for wave winding, the front pitch, Y
f
= Y - Y
b
3.21
Example 3.10 : Determine the back and front pitches for a 4 pole wave winding with 25 slots.
Fig.3.10 - Wave winding
Solution : P = 4, C = 25, winding type = wave
From equation 3.17, the back pitch,
(odd integer)
From equation 3.19, the winding pitch, Y = = 26 (even integer)
From Fig. 3.10 or from equation 3.21, front pitch, Y
f
= 26 – 13 = 13 (odd integer).
3.10 WHOLE COIL WINDING : A whole coil winding is one in which the number of coils per
phase is equal to the number of poles in the machines. In this type of winding, as shown in Fig.
3.11 (a), each slot contains two coil sides. It is not, however, strictly a double layer winding, as
the coil sides are places side by side and not one above the other.
3.11 HALF COIL WINDING : It is that winding in which the number of coils per phase is equal to
Fig.3.11 - Representation of whole coil and half coil
Commutator Segments
N1 S1 N2
Y
Y
f
Y
b
(a) Whole coil winding
(b) Half coil winding
S SN N
S S SNNN
2 C
P
2×25
4
Y
b
= + K = + K = 12.5 + K = 13
2C+2
P
2
2×25+2
4
2
=