High-power equipment such as generators, transformers, and transmission lines are built as three-phase equipment. The three-phase system has many advantages over the single-phase system; the most important ones are as follows:
- Three-phase systems produce a rotating magnetic field inside the alternating current (ac) motors and, therefore, cause the motors to rotate without the need for extra controls. Since electric motors constitute the majority of electric energy consumed worldwide, having a rotating magnetic field is a very important advantage of three-phase systems. The theory of rotating fields is explained in Chapter 12.
- Three-phase generators produce more power than single-phase generators of equivalent volume. ...