I need some explanation about Shaded-Pole Motor.
In the book: "Electric Motors and Control Systems" by Frank D. Petruzella (published by McGraw-Hill), in Chapter 5, Part 4, on page 113 under "Shaded-Pole Motor" it is written that:
Unlike other types of single-phase motors, shaded-pole motors have only one main winding and no start winding or switch. As in other induction motors, the rotating part is a squirrel-cage rotor. Starting is by means of a design that uses a continuous copper loop around a small portion of each motor pole, as illustrated in Figure 5-51. Currents in this copper loop delay the phase of magnetic flux in that part of the pole enough to provide a rotating field. This rotating field effect produces a very low starting torque compared to other classes of single-phase motors. Although direction of rotation is not normally reversible, some shaded-pole motors are wound with two main windings that reverse the direction of the field. Slip in the shaded-pole motor is not a problem, as the current in the stator is not controlled by a countervoltage determined by rotor speed, as in other types of single-phase motors. Speed can therefore be controlled merely by varying voltage, or through a multitap winding.
But when looking on the motor I have, it seems that copper wire is circulating through whole main winding, instead of only part of it. So how is it that additional magnetic field can be generated, to turn the rotor into motion?