Specifications

1 8 3 10 5 12

6 11 4 9 2 7

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. 5.7.

Draw the vertical solid lines equal to number of coil sides and join them with reference to

Table 5.3, as shown in Fig.5.7. Also mark the current direction through the coil sides with

reference to main winding diagram in Fig. 5.7.

Look for adjacent pair of coil sides having the same current direction. For coil sides 12 and

7 carry which carry upward currents, mark negative brush arm, and for coil sides 6 and 1 carry

downward currents, mark positive brush arm, as shown in Fig. 5.7. Brush arms should be

equal to the number of poles.

Fig. 5.7 - Commutator ring diagram

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. 5.7 as

shown in Fig. 5.8.

Fig. 5.8 - Parallel paths for 2 pole 6 slot simplex lap winding

From Fig. 5.8, 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 5.3

where A = number of parallel paths; The current through each armature coil / conductor

will be the ratio of the total armature current by the number of parallel paths, ie.,

1 11

212

10 8