Open coil winding and Closed coil winding of DC machine

Open coil winding and closed coil winding are the types of Armature windings. Armature windings are the non-salient pole type and usually are symmetrically distributed in the slots of the complete circumference of the armature.

Basically two types of armature windings according to the degree of closure produced:

Open Coil Winding:

Open coil windings are defined as windings that do not close themselves electrically until the external connection is made to a source or load. The open coil winding is never employed in DC machines it is only used in AC machines.

Closed Coil Winding:

A Closed coil winding is defined as the winding which closes itself electrically. In such a winding there is no need for the external source or load to close the circuit. A DC machine always employs closed coil winding in order to provide the Commutation requirement of the coils.

In closed coil winding if one starts from one end of the winding he will come back to the same position without traveling through the source or the load.

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