Number of parallel paths in DC machine

 lap winding :

This is the lap winding diagram of DC machine. It is for 4 pole and 20 slot armature.

As we know no. of commutator segments=no. of armature coils(C).

So from the above diagram we can easily find that five coils(C/P) are located under one pole-pair(NS) and are series connected so that their emfs add up.This constitute one parallel path. So the complete armature winding can be divided into such four paths(equal to the no. of poles) lying under the four poles. So it can be concluded that no. of parallel path in lap-wound machine is equal to no. of poles.

wave winding:

In wave winding the "finish" end of one coil under "one pole pair" is connected to "start" of a coil under the "next pole pair".

The process is continued till all the armature coils are connected and winding becomes a closed one.Wave name is only due to appearance.

In wave winding the coils are divided into two groups-All the coils with clockwise current are series connected and all the coils with counter clockwise current are series connected. These two groups are in parallel because the winding is closed. Thus a wave winding has always two parallel paths irrespective of the no. of poles and only two brushes are required.This type of winding is used for low-current, high voltage application.