Kohler 10EOR, Service

Page: 47 / 84

TP-6073 4/06 47 Section 7 Generator Troubleshooting
F+
F--
AC
AC
AC
1
2
3
4
5
6
TP-5936510
1. Main field (rotor)
2. Stator windings
3. Rectifier module 4. Ohmmeter
5. Armature
6. Exciter field
Figure 7-15 Exciter Armature Ohmmeter Test
F+
F--
AC
AC
AC
1
2
3
4
5
6
7
TP-5936511
1. Main field rotor
2. Stator windings
3. Rectifier module
4. Megohmmeter 5. Shaft connection
6. Armature
7. Exciter field
Figure 7-16 Megohmmeter Connections on Exciter
Armature
7.9 Exciter Armature (EORZ and
EFORZ Models)
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 9.
2. With the alternator disassembled, disconnect the
armature leads from the rectifier module AC
terminals. Refer to Section 9.
3. With an ohmmeter on the R x 1 scale, check the
resistance across the exciter armature leads. See
Figure 7-15. See Section 1.3, Specifications, for
the armature resistance. No continuity indicates
an open armature winding. If the resistance test is
inconclusive, perform a megohmmeter test on the
exciter armature as described in the next step.
Note: Consider the exciter armature good 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
armature frame.
Follow the megohmmeter
manufacturer’s instructions for using the
megohmmeter. See Figure 7-16. 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.
7.10 Rectifier Module (EORZ and
EFORZ Models)
The rectifier module converts the AC from the exciter
armature to DC, which magnetizes the generator main
field.
Test the rectifier module as described in the
following steps.
Rectifier Module Test Procedure:
1. Disconnect the exciter armature and the main field
leads from the rectifier module.