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AC Alternating Current Generators Review
AC Alternating generators are considered either brush or brushless, based on the method used to transfer DC exciting current to the generator field. In addition, AC generators are classified as salient-pole or nonsalient-pole depending on the onfiguration of the field poles. Projecting field poles are salient-pole units and turbo-type (slotted) field poles are nonsalient-pole units.
Damper windings on the rotor stabilize the speed of the AC generator to reduce hinting under changing loads. If the speed tends to increase, induction-generator action occurs in the damper windings. This action places a load on the rotor, tending to slow the machine down. If the speed tends to decrease, induction-motor action occurs in the damper winding, tending to speed the machine up. The windings are copper bars located in the faces of the rotor pole pieces. Mounted parallel to the rotor axis, the bars are connected at each end by a copper ring.
AC generators that operate at a speed that is exactly proportional to the frequency of the output voltage are synchronous generators. Synchronous generators are usually called alternators.
References: “Joint Departments of the Army and the Navy, Operation Maintenance and Repair of Auxiliary Generators, 26 August 1996”