Kohler EKOZD Series Service page 176

10.3.1 Exciter Armature
WARNING
Hot engine and exhaust system.
Can cause severe injury or death.
Do not work on the generator set until
it cools.
Servicing the alternator. Hot parts can cause severe
injury or death. Avoid touching the alternator field or exciter
armature. When shorted, the alternator field and exciter
armature become hot enough to cause severe burns.
WARNING
Hazardous voltage.
Can cause severe injury or death.
Operate the generator set only when
all guards and electrical enclosures
are in place.
High voltage test. Hazardous voltage can cause severe
injury or death. Follow the instructions of the test equipment
manufacturer when performing high-voltage tests on the rotor
or stator. An improper test procedure can damage equipment
or lead to generator set failure.
The exciter armature supplies excitation current to the
generator main field through the rectifier module. Test
the exciter armature as described in the following steps.
Exciter Armature Test Procedure
1. Disassemble the alternator. Refer to Section 15,
Generator Disassembly/Reassembly.
2. With the alternator disassembled, disconnect the
exciter armature leads from the rectifier module AC
terminals
3. With an ohmmeter on the R x 1 scale, check the
resistance across the exciter armature leads. See
Figure 10-5. See Section 1, Specifications, for the
exciter armature resistance.
176 Section 10 Alternator Component Testing and Adjustment
Moving parts.
6
5
4

1. Main field (rotor)
2. Stator windings
3. Rectifier module
Figure 10-5 Exciter Armature Ohmmeter Test
No continuity indicates an open exciter armature
winding. If the resistance test is inconclusive,
perform a megohmmeter test on the exciter
armature as described in the next step.
Note: Most ohmmeters
measure less than one ohm. Consider the
exciter armature functional if the resistance
reading (continuity) is low and there is no
evidence of a shorted winding (heat
discoloration).
4. Check the exciter armature winding for a
short-to-ground condition. Use a megohmmeter to
apply 500 volts DC to either armature lead and the
exciter armature frame. Follow the megohmmeter
manufacturer's instructions
megohmmeter. See Figure 10-6.
A reading of approximately 1.5 MOhms and higher
indicates the exciter armature 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 armature.
1
F+
AC
AC
AC
F-
3
2
TP-6878-3
4. Ohmmeter
5. Exciter armature
6. Exciter field winding
will not accurately
for using the
TP-6953 7/19