1. How does a three-phase motor work?

Three-phase motors are operated with three-phase alternating current or "three-phase current". This type of current carries a separate periodically changing voltage in each of three separate conductors, the timing of which is offset by 120° in relation to the other two conductor voltages. If three electromagnet coils are each fed with one phase of the three-phase current system, a magnetic field is generated in each coil, the timing of which, like the voltage curve, is offset by a third of a period in relation to the other coil fields. If these three coils are arranged in a circle in relation to each other, the individual coil magnetic fields result in a summed magnetic field that is of constant size but changes its direction continuously in exact accordance with the frequency or period repetition of the three-phase current. This summed magnetic field "rotates" at the exact speed specified by the frequency. With 50 period changes per second of the three-phase current (or 50 Hz), the magnetic field also rotates around itself 50 times per second (corresponding to 3000 times per minute). If a magnetic object, for example a bar magnet or a simple iron body, is inserted into this rotating magnetic field on a central axis, the rotor is also rotated.