Shading coil

Element used in an AC magnetic circuit

A shading coil or shading ring is one or more turns of electrical conductor located in the face of the magnet assembly or armature of an alternating current solenoid. The alternating current in the energized primary coil induces an alternating current in the shading coil. This induced current creates an auxiliary magnetic flux which is 90 degrees out of phase from the magnetic flux created by the primary coil.

This keyword could refer to multiple things. Here are some suggestions: