shading coil

In this motor, small single-turn copper "shading coils" create the moving magnetic field.

This auxiliary single-turn winding is called a shading coil.

This causes a time lag in the flux passing through the shading coil, so that the maximum field intensity moves across the pole face on each cycle.

Both shading coils were probably closer to the main coil; they could have both been farther away, without affecting the operating principle, just the direction of rotation.

One of the pair of discs distributes the coil's flux directly, while the other receives flux that has passed through a common shading coil.

Like a shaded pole induction motor, they use field coils with additional copper shading coils (see the illustration) to produce a weakly rotating magnetic field.

Each pole face was split, and had a shading coil on one part; the shading coils were on the parts that faced each other.

Low-power synchronous timing motors (such as those for traditional electric clocks) may have multi-pole PM external cup rotors, and use shading coils to provide starting torque.

For contactors energized with alternating current, a small part of the core is surrounded with a shading coil, which slightly delays the magnetic flux in the core.