TP-6811 7/16 75Section 6 Component Testing and Adjustment
Section 6 Component Testing and Adjustment
6.1 Theory of Operation
The generator set utilizes a rotating-field alternator to
produce AC voltage. There are two types of alternator
available: single phase (see Figure 6-1) and three
phase (see Figure 6-2). The alternator is excited by a
permanent magnet brushless exciter, providing superior
motor starting capability, fault current, transient
performance, and longevity.
The generator set produces AC voltage by rotating a
magnetic field inside the stator windings. This magnetic
field is produced by current in the rotor windings (or
field). The current is generated in the exciter armature
by rotating in the fixed magnetic field produced by
permanent magnets attached to the rotor bearing
assembly on the back of the alternator.
The field current is controlled b y the RDC2 controller
using a PWM (pulse-width modulated) signal which
drives an LED on the stationary LED board (SLB)
(mounted under the end cover on the alternator) varying
the intensity of the light to the rotating exciter board. The
rotating exciter board controls the field current in the
rotor based on the intensity of the light received by the
photo-detector.
1
1. Excitation control circuit (3B, 5B)
2. Excitation control stationary LED board (SLB)
3. Rotating photo exciter board
4. Permanent exciter magnets
5. Exciter armature
6. Main field (rotor)
7. Stator windings
8. Sensing leads (11 and 44)
8
6
5
4
3
2
7
Figure 6-1 Single-Phase Generator Schematic
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7
6
5
4
3
2
1
1. Excitation control circuit (3B, 5B)
2. Excitation control stationary LED board (SLB)
3. Rotating photo exciter board
4. Exciter armature
5. Permanent exciter magnets
6. Main field (rotor)
7. Stator windings
8. Sensing leads
Figure 6-2 Three-Phase Generator Schematic
6.2 Alternator Excitation
Troubleshooting
Hazardous voltage.
Can cause severe injury or death.
Operate the generator set only when
all guards and electrical enclosures
areinplace.
Moving parts.
WARNING
Servicing the generator set when it is operating. Exposed
moving parts can cause severe injury or death. Keep
hands, feet, hair, clothing, and test leads away from the belts
and pulleys when the generator set is running. Replace
guards, screens, and covers before operating the generator
set.
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