Kohler EKOZD Series Service page 175

8. Use a voltmeter and check for AC output across the
stator main windings and compare it to the values
in Section 1, Specifications. If the stator main
windings output varies considerably from those
listed, a faulty stator, rotor, rectifier module, or
exciter armature is likely.
9. Stop the generator set. Refer to the operation
manual as needed.
If there is no alternator AC output during normal
operation, but AC output is available when the generator
set is separately excited, the voltage regulator is
probably defective.
Note: See Section 1, Specifications, for the stator
output voltages
alternator). These specifications are based on a
battery voltage of 12. Should the battery voltage
vary (11- 14 volts), the resulting stator output
values will also vary.
10.3 Exciter Field
Direct current from the battery magnetizes the exciter
field. When the exciter armature rotates within the
magnetized exciter field windings, an electrical current
develops within the exciter armature. Test the exciter
field according to the following procedure.
Exciter Field Test Procedure
1. Stop the generator set. Refer to the operation
manual as needed.
2. Disconnect the generator set engine starting
battery, negative (- ) lead first.
3. Disconnect the FP/FN connector between the
controller/activator board and the exciter field.
4. Check the exciter field resistance by connecting an
ohmmeter across exciter field FN and FP leads.
See Figure 10-3. See Section 1, Specifications, for
the resistance value of a cold exciter field.
A low reading indicates an internal short and a high
reading indicates an open winding.
replace the exciter field if the ohmmeter readings
indicate an inoperative exciter field (refer to
Section 15, Generator Disassembly/Reassembly,
for removal).
If the resistance test is inconclusive, perform a
megohmmeter test on the exciter field as described
in the next step.
TP-6953 7/19
(with separately excited
Repair or
1
5
1. Generator set controller/
activator board
2. Ohmmeter
Figure 10-3 Exciter Field Resistance Test
5. Check the exciter field for a short-to-ground
condition. Use a megohmmeter to apply 500 volts
DC to the FN or FP lead and the exciter field frame.
See Figure 10-4.
manufacturer's instructions for megohmmeter use.
A reading of approximately 1.5 MOhms and higher
indicates the field winding is functional. A reading
of less than approximately 1.5 MOhms indicates
deterioration of the winding insulation and possible
current flow to ground; if so, replace the exciter
field.
1
5
6
1. Generator set controller/
activator board
2. Megohmmeter
3. Frame connection
Figure 10-4 Megohmmeter Connections on the
Exciter Field
Section 10 Alternator Component Testing and Adjustment
2

FN FP 3
4
TP-6878-3
3. Exciter field
4. Exciter armature
5. Main field (rotor)
Follow the megohmmeter
2

FN FP
3
4
TP-6878-3
4. Exciter armature
5. Exciter field
6. Main field (rotor)
175