Test 13 - Check Brushes & Slip Rings; Test 14 - Check Rotor Assembly - Generac Power Systems GP Series Diagnostic And Repair Manual

Section 4 AC Diagnostic Tests
b. If continuity is not measured repair or replace
wire 0 between the C1 connector and the
ground terminal.
Results
Repair or replace wiring/terminals as needed.
1.
If no faults are found refer to flow chart.
2.
Figure 4-21. Brush Leads
Test 13 – Check Brushes & Slip Rings
Procedure
Gain access to the brushes and slip rings.
1.
Figure 4-22. Brush Location
Remove wire 4 from the positive (+) brush terminal.
2.
Remove the ground wire (0) from the negative (-)
3.
brush.
Remove the brush holder, with brushes.
4.
Inspect the brushes for excessive wear, damage,
5.
cracks, chipping, etc.
Inspect the brush holder. Replace if damaged.
6.
Inspect the slip rings.
7.
a. If slip rings appear dull or tarnished they may
be cleaned and polished with fine sandpaper.
DO NOT USE ANY METALLIC GRIT TO
CLEAN SLIP RINGS. (A 400 grit wet
sandpaper is recommended).
b. After cleaning slip rings, blow away any
sandpaper residue.
44
Results
Replace bad brushes. Clean slip rings, if neces-
1.
sary.
If brushes and rings are good, go to Test 14.
2.
Test 14 – Check Rotor Assembly
Procedure
Gain access to the brushes and slip rings. Disconnect
wire 4 and wire 0 from their respective brushes and
remove the brush holder. Then, test the Rotor as follows:
Set DMM to measure resistance.
1.
Connect the positive (+) meter test lead to the
2.
positive (+) slip ring (nearest the rotor bearing).
Connect the common (-) test lead to the negative (-)
3.
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slip ring.
Read the resistance of the rotor windings, in ohms.
4.
Connect the positive (+) meter test lead to the
5.
positive (+) slip ring.
Connect the common (-) test lead to a clean frame
6.
ground (such as the rotor shaft).
a. Infinity should be measured.
kW
12.5
15.0
17.5
* Resistance values in ohms at 20 °C. (68 °F.). Actual readings
may vary depending on ambient temperature. A tolerance of
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plus or minus 5% is allowed.
Results
Replace the rotor if it fails the test.
1.
If rotor checks good, perform
2.
Resistance
Figure 4-23. Testing at Slip Rings
Rotor Resistance *
Ohms
7.01 Ω
8.48 Ω
9.33 Ω
Rotor Insulation
Test.
POSITIVE (+)
TEST LEAD
Diagnostic Repair Manual
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