Static Magnetic Exciter for Synchronous Alternators

The paper illustrates the application of the theory of electric machinery to the practical design of a static magnetic exciter. The basic exciter circuit is of such nature as to make the alternator (which is energized by the exciter) as much self-regulating as possible. Remaining deviations of the alternator voltage affect a voltage-sensitive circuit which provides a correction signal to the exciter. The energy for the exciter is obtained entirely from the alternator. With this system, no antihunt means are needed, and the steady-state alternator voltage can be easily held within ±0.6 per cent. The transient response is rapid and yet well damped. A short circuit of the alternator will not cause loss of excitation; as a matter of fact, during a short circuit the excitation becomes several times normal, a feature which is desirable for the selective tripping of protective devices.