Kohler 27EFOZ, Service Manual

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TP-5936 7/04 31 Section 7 Generator Troubleshooting
7.6 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. Place the start/stop switch in the STOP position.
2. Disconnect the generator set engine starting
battery, negative (--) lead first.
3. Disconnect the P6 connector (F1/F2 leads).
4. Check the exciter field resistance by connecting an
ohmmeter across exciter field F1 and F2 leads.
See Section 1, Specifications, for the resistance
reading for a cold exciter field.
A low reading
indicates an internal short and a high reading
indicates an open winding. Repair or replace the
exciter field if the ohmmeter readings indicate a
inoperative exciter field (Refer to Section 9 for
removal). If the resistance test is inconclusive,
perform a megohmmeter test on the exciter field as
described in the next step.
5. Check the exciter field for a short to ground
condition. Use a megohmmeter to apply 500 volts
DC to the F1 or F2 lead and the exciter field frame.
Follow
the megohmmeter manufacturer’s
instructions for using the megohmmeter. A reading
of approximately 500 kOhms (1/2 megohm) and
higher indicates the field winding is good.
A
reading of less than approximately 500 kOhms
indicates deterioration of the winding insulation
and possible current flow to ground. Replace the
exciter field.
1
3
4
F1 F2
P6
TP-593658
2
1. Voltage regulator
2. Ohmmeter
3. Exciter field
4. Exciter armature
Figure 7-6 Exciter Field Resistance Test
1
3
F1 F2
P6
4
5
TP-593659
2
1. Voltage regulator
2. Ohmmeter
3. Frame connection 4. Exciter armature
5. Exciter field
Figure 7-7 Megohmmeter Connections on the
Exciter Field