Kohler 40COZ/33CFOZ - 7.7 Generator Field

TP-5737 5/01 69Section 7 Component Testing and Adjustment
7.7 Generator Field
Hazardous voltage.
Can cause severe injury or death.
Operate the generator set only when
all guards and electrical enclosures
areinplace.
Moving rotor.
WARNING
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.
Hot engine and exhaust system.
Can cause severe injury or death.
Do not work on the generator set until
it cools.
WARNING
Servicing the generator. Hot parts can cause severe
injury or death. Avoid touching the generator set field or
exciter armature. When shorted, the generator set field and
exciter armature become hot enough to cause severe burns.
Generator Field Test
1. Disconnect the generator set engine starting
battery, negative (--) lead first.
2. Remove the end bracket. See Section 7.9, End
Bracket Removal and Replacement, and
Section 8, Disassembly/Reassembly.
3. Disconnect F+ and F-- from the SCR assembly.
4. With an ohmmeter, check for continuity across the
F+ and F-- leads (see Figure 7-14). Resistance
readings are shown in Section 1, Specifications,
Generator.
5. Check for a grounded generator field. No
continuity should exist between the field leads and
the rotor assembly.
6. Using a megohmmeter, apply 500 volts DC to the
F+ or F-- lead and the rotor shaft. See Figure 7-15.
Follow the instructions of the megohmmeter
manufacturer when performing this test. A reading
of approximately 5--7 kOhms and higher indicates
the field winding is functional. A reading of less
than 5--7 kOhms (approximately) indicates
deterioration of the winding insulation and possible
current flow to ground.
7. Repair or replace the rotor assembly.
Repair the F+ and F-- leads if this test shows the
leads are shorted to ground. If using splices, solder
and insulate the splices. Use new sleeving when
tying the leads to the shaft or the heat sink.
Replace the generator rotor assembly if this test
shows a shorted or grounded winding.
9
3-100
R12758-8
TP-5353-7
1
1. Ohmmeter connections across F+ and F-- leads
Figure 7 -14 Field Continuity Check