ARMY TM 9-6115-643-24
AIR FORCE TO 35C2-3-445-22
4.15 TECHINCAL DESCRIPTION.
MAINTENANCE OF GENERATOR ASSEMBLY
General. Revolving field type generators have a DC field revolving within a stationary AC winding called the
stator. AC power is distribution from the generator through leads connected to the stator windings. There are no sliding
contacts between the AC winding and the load, therefore, great amounts of power maybe drawn from this generator. -
N O TE
Refer to FIGURE 4-7 as needed.
To energize the field, DC excitation must be applied to the generator field coils. The excitation current is supplied
from a brushless exciter mounted on the generator shaft.
The brushless exciter is actually an AC generator with its output rectified through a full wave bridge circuit. This type
of brushless exciter will provide the necessary excitation current. The generator set field flash circuit, activated during each
engine start, applies voltage to the exciter stator to begin the voltage build-up process to enegize the generator field.
The generator output voltage is controlled by controlling the alternating field current. This is accomplished by regu-
lating the exciter field coil voltage. The exciter field coil voltage is regulated with a solidstate-type voltage regulator.
FIGURE 4-7. Brushless Generator Schematic
4.15.2 Damper Bars. Damper bars are inserted through the field laminations and welded at the end to a solid copper
plate. The damper windings provide stable parallel operation, reduce damping current losses, and limit the increase of
third harmonic voltage with increase in load.
Brushless Exciter. The brushless exciter consists of an armature with a three-phase AC winding and rotating
rectifier assembly within a stationary field.