Specifications

73
1
8
15
22
3
10
17
24
5
12
19
26
+
-
1 6 25 18 11 4 23 16 9 2 21
+
-
7
14
20
13
A
AA
Fig. 5.10 - Commutator ring diagram
for the coil sides under the north pole regions and upward current direction under south pole
regions, as shown in Fig. 5.9.
To fix the brush arm positions and to find the number of parallel paths offered by the armature
winding, commutator ring diagram is used, as shown in Fig. 5.10.
Look for adjacent pair of coil sides having the same current direction. For coil sides 26 and
7 carry which carry upward currents, mark negative brush arm, and for coil sides 20 and 1 carry
downward currents, mark positive brush arm, as shown in Fig. 5.10.
Now, transfer the brush arms to the main winding diagram. Mark positive brush arm below
the commutator segment 1, where the coil sides 1 and 6 meet. Similarily, mark negative brush
arm below the commutator segment 4, where the coil sides 2 and 12 meet. Tap out two leads
and mark A for positive brush arm and AA for negative brush arms. These two leads now
indicate the armature terminals of a dc machine.
To decide the number of parallel paths offered by the wave winding, redraw Fig. 5.10 as
shown in Fig.5.11.
Fig. 5.11 - Parallel paths for 4 pole 13 slot simplex wave winding
From Fig. 5.11, it can be seen that the number of parallel paths in a wave winding, will be
equal to two, ie., 2, irrespective to the number of poles.
A = 2
where A = number of parallel paths.
1153 7 917
5
19
21 23 11
25
13
82210 14 1624
12
26
2418
6
20
1
-
+-
+