Kohler 11RMY, Service Manual

Page: 45 / 98

TP-5867 11/02 35 Section 6 Component Testing and Adjustment
Section 6 Component Testing and Adjustment
6.1 Theory of Operation, 1-Phase
Generator Sets with Power
Boost IIIE Voltage Regulator
Single-phase 8.5/11RMY generator sets utilize a
rotating-field alternator to produce AC current. Upon
activation of the generator master switch, DC current
from the battery magnetizes the rotor (field). When the
magnetized rotor rotates within the stator windings, an
electrical current develops within the stator. As engine
speed and generator output increase, the voltage
regulator feeds rectified stator output current to the rotor
through the brushes/slip rings to increase the strength of
the rotor field. As the rotor field increases in strength,
generator output also increases. The Power Boost
t
IIIE voltage regulator monitors the generator output
voltage through leads 33 and 44 and allows the DC
current to flow to the rotor to meet load requirements.
See Figure 6-1.
6.2 Generator Troubleshooting
To determine the cause of no or low AC output, refer to
the troubleshooting flow chart in Figure 6-2.
Before
beginning the test procedures, read all safety
precautions at the beginning of this manual. Many of the
test procedures include additional safety precautions.
Check the condition of the voltage regulator’s 10-amp
fuse
before performing the separate excitation
procedure. See Figure 4-2 or Figure 4-3 for the fuse
location.
If the fuse is not blown, use the following
procedure to separately excite the generator using an
external voltage source (a 12-volt automotive battery).
Separately exciting the generator can determine the
presence of a faulty voltage regulator or reveal a running
fault in the rotor and/or stator. An external power source
duplicates the role of the voltage regulator and excites
the generator field (rotor). A generator component that
appears to be in good condition while stationary may
exhibit a running open or short circuit while moving.
Centrifugal forces acting on the windings during rotation
cause a broken circuit to open, or increasing
temperatures cause the insulation to break down,
resulting in a running fault. If this test shows that the
rotor and stator are in good condition, test the voltage
regulator using the tests in Section 6.3.
+ --
55
44
33
66
3
4 55 2 1
44
33
4
3
1 2
9
8
2
6 5
7
TP563271
1. Excitation to rotor
2. Stator windings
3. Voltage regulator PowerBoost
ä
IIIE
4. 10-amp voltage regulator fuse (controller front panel)
5. Sensing leads (33--44)
6. Power lead (55)
7. Main field (rotor)
8. Slip rings
9. Brushes
Figure 6-1 Single-Phase Generator Schematic
No Generator Output
Separate Excitation
Output within
Specifications
Check Rotor
Voltage Regulator
and Wiring
Check Stator
TP563273
Erratic or No Output
Figure 6-2 Generator Troubleshooting