Armature Winding and Types of Armature Winding

Armature Winding:

The armature winding is the main current-carrying winding in which the electromotive force or counter-emf of rotation is induced. The current in the armature winding is known as the armature current. The location of the winding depends upon the type of machine.

Generally there are two types of Armature winding in the DC machines. They are classified as follow,

  1. Lab winding
  2. Wave winding

 armature winding

The difference between these two is merely due to the end connections and commutator connections of the conductor. To know how armature winding is done, it is essential to know the following terminologies –

  1. Pole pitch: It is defined as number of armature slots per pole. For example, if there are 36 conductors and 4 poles, then the pole pitch is 36/4=9.
  2. Coil span or coil pitch (Ys): It is the distance between the two sides of a coil measured in terms of armature slots.
  3. Front pitch (Yf): It is the distance, in terms of  armature conductors, between  the second conductor of one coil and the first conductor of the next coil. OR it is the distance between two coil sides that are connected to the same commutator segment.
  4. Back pitch (Yb): The distance by which a coil advances on the back of the armature is called as back pitch of the coil. It is measured in terms of armature conductors.
  5. Resultant pitch (Yr): The distance, in terms of armature conductor, between the beginning of one coil and the beginning of the next coil is called as resultant pitch of the coil.


Armature winding can be done as single layer or double layer. It may be simplex, duplex or multiplex, and this multiplicity increases the number of parallel paths.

Lap winding and Wave winding

In lap winding, the successive coils overlap each other. In a simplex lap winding, the two ends of a coil are connected to adjacent commutator segments. The winding may be progressive or retrogressive. A progressive winding progresses in the direction in which the coil is wound. The opposite way is retrogressive. The following image shows progressive simplex lap winding.
 armature winding
Lap Winding: This type of winding is used in dc generators designed for high-current applications. The windings are connected to provide several parallel paths for current in the armature. For this reason, lap-wound armatures used in dc generators require several pairs of poles and brushes.
In wave winding, a conductor under one pole is connected at the back to a conductor which occupies an almost corresponding position under the next pole which is of opposite polarity. In other words, all the coils which carry emf in the same direction are connected in series. The following diagram shows a part of simplex wave winding.
armature winding
Wave Winding: This type of winding is used in dc generators employed in high-voltage applications. Notice that the two ends of each coil are connected to commutator segments separated by the distance between poles. This configuration allows the series addition of the voltages in all the windings between brushes. This type of winding only requires one pair of brushes.

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