The current that flows in the armature winding of a D.C. motor tends to produce magnetic flux in addition to that produced by the field current. This effect, which reduces the torque capacity, is call [..]

The effect caused by the interaction of the magnetic field of the current carrying conductors in the armature with the main magnetic field. The two magnetic fields combined cause a distortion in the overall magnetic field that results in a shift in the neutral plane in the direction of armature rotation.

The effect in a dc generator of current in the armature creating a magnetic field that distorts the main field and causes a shift in the neutral plane.

The effect, that the magnetic field produced by the current flowing in the armature, has on the magnetic field produced by the field coils.