ROTOR CONSTRUCTION in alternators may be either of two types. The salient-pole rotor is
used in slower speed alternators. The turbine driven-type is wound in a manner to allow high-speed use
without flying apart.
GENERATOR RATINGS are dependent on the amount of current they are capable of providing at
full output voltage; this rating is expressed as the product of the voltage times the current. A 10-volt
alternator capable of supplying 10 amperes of current would be rated at 100 volt-amperes. Larger
alternators are rated in kilovolt-amperes.
EXCITER GENERATORS are small dc generators built into alternators to provide excitation
current to field windings. These dc generators are called exciters.
The SINGLE-PHASE ALTERNATOR has an armature that consists of a number of windings
placed symmetrically around the stator and connected in series. The voltages generated in each winding
add to produce the total voltage across the two output terminals.