This chapter on balanced three-phase theory assumes no unbalanced loads, power line faults, or symmetrical components type questions on the examination. This introduction to three-phase theory will begin with an oversimplified synchronous alternator (involving a synchronous reactance term--but mostly ignored in this chapter) producing a three-phase voltage; this is important since in the next chapter on ac machines, the synchronous reactance concept will be considered.

The three-phase equations given in THE REFERENCE HANDBOOK only account for the simplest types of problems but it is important to know whether only the magnitude or the actual phasor equation is needed. If another reference text for review is needed, this author suggests only a circuits or machines type book be consulted. Don't get "bogged down" with all of the ramifications of symmetrical components, per unit values, and other techniques of analysis that might be expected in a more specialized book.

Three-Phase Generation:

For an oversimplified three-phase synchronous alternator (generator), consider figure 3.1 where the poles (on the rotor) is driven at a fixed speed, ?. The effect of the field pole(s) is/are to produce a rotating magnetic vector which, in turn, produces a voltage in the stator windings, a function of the dc field current. On the other hand, if the rotor weren't there and another three-phase voltage source were connect to the terminals, the resulting current in the windings would produce its own rotating magnetic vector. Now, if both vectors were present and in synchronism, the angle between these two vectors...