Kohler Power Systems 8RESV Service Manual page 81

Rotor Test Procedure
1. Press the OFF button on the controller to turn off
the generator set.
2. Disconnect utility power to the generator set.
3. Disconnect the generator set engine starting
battery, negative (--) lead first.
4. Check the rotor for continuity and resistance.
While performing ohmmeter tests, remove the two
brush holder mounting screws. raise the brushes
from the slip rings, and then move and secure the
brushes out of the way. Measure the rotor
resistance (ohms) between the two slip rings; see
Figure 5-7. See Section 1.5 for rotor resistance
readings. If the resistance readings are low,
perform a megohmmeter test on rotor as described
in the next step.
Note: Because ohmmeter
resistance readings are approximate. Take
readings at room temperature.
5. Perform a megohmmeter test to determine
whether the rotor is shorted to ground.
a. Remove the two brush holder mounting
screws. Raise the brushes and then move and
secure the brushes out of the way.
b. Using a megohmmeter, apply 500 volts DC to
one rotor slip ring and the rotor poles or shaft.
TP-6881 7/15
accuracy varies,
Follow the instructions of the megohmmeter
manufacturer when performing this test.
Note: A reading of approximately 500 kOhms
(1/2 megohm) or higher indicates a
good rotor.
c. Repair or replace the rotor if the reading is less
than approximately 500 kOhms. A reading of
less than 500 kOhms indicates deterioration of
the winding insulation and possible current flow
to ground.
d. Following the test, remove the retainer wire
from the brush holder and check the brush
positions on the slip rings. See Section 5.7,
Brushes.
Figure 5-7 Rotor Resistance Check
Section 5 Component Testing and Adjustment
2-221
R13929-7
81