Specifications

71
where I = current through each armature conductor/coil; I
A
= total armature current
Problem 2 :
Develop a winding diagram for a 4 pole, 13 slot double layer simplex wave connected dc
machine with 13 commutator segments. Indicate the position of brushes.
Solution: Number of coils, C = number of commutator segments = 13; Number of coil
sides = 2C = 26; Therefore, coil sides per slot =
= 2 ; The back pitch, Y
b
= =
6.5 + 0.5 = 7 (odd integer); The winding pitch,Y = = 14 (even integer); Here m = 1
for simplex wave winding. The front pitch, Y
f
= Y – Y
b
=14 – 7 = 7 (odd integer).
Table 5.4 gives the winding table for 4 pole 13 slot simplex wave winding.
Table 5.4: Winding table
To draw the main winding diagram, first draw 13 solid vertical lines (equal to no. of coils) of
S.No.
Top coil Side
(+Y
f
)
Bottom coil Side
(+Y
b
)
11 8
215 22
3 (29-26) 3 10
417 24
1 (31 – 26) 5 12
219 26
3 (33 - 26) 7 14
4 21 (28 – 26) 2
59 16
6 23 (30 – 26) 4
711 18
8 25 (32 – 26) 6
913 20
equal length and equal distance. Next, draw 13 dotted lines nearer to the solid lines of same
length and distance, as shown in Fig. 5.9.
Give the back end and front end connections with reference to the Table 5.4. Divide the
armature slots (or coils) by the number of poles. This gives the allocation of coil sides to pole
regions. In this example, the coil sides 13 and 14 lie in the interpolar region. So a ‘O’ is marked,
as shown in Fig. 5.9.
Find the current direction by applying Fleming’s right hand rule, when the mode of operation
is a generator and Fleming’s left hand rule, when the mode of operation is a motor. Or the
current direction to all coil sides can be arbitrarily assumed. Mark downward current direction
I =
I
A
A
2 C
P
26
4
+ K= + K
26+2
2
2C+2m
P
2
=