Abstract:
The purpose of the electric transmission system is the interconnection of the electric energy producing
power plants or generating stations with the loads. A three-phase AC system is used for most transmission
lines. The operating frequency is 60 Hz in the U.S. and 50 Hz in Europe, Australia, and part of Asia. The
three-phase system has three phase conductors. The system voltage is defined as the rms voltage between
the conductors, also called line-to-line voltage. The voltage between the phase conductor and ground,
called line-to-ground voltage, is equal to the line-to-line voltage divided by the square root of three.
Figure 4.1 shows a typical system.
