TP-6519 8/1752 Section 5 Component Testing and Adjustment
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Figure 5-6 Three-Phase Alternator Stator Leads
6. Contact the ohmmeter leads and readjust the
ohmmeter to read zero ohms.
7. Check the cold resistance of the stator windings by
connecting the meter leads to stator leads 1-2, 3-4,
and 55-66. See Section 1.5, Alternator
Specifications, for stator winding resistances.
Most ohmmeters do not provide accurate readings
below 1 ohm. Low resistance readings (continuity)
and no evidence of shorted w indings (heat
discoloration) indicate a stator in good condition.
SeeFigure5-7.
Leads Continuity
1 and 2
Yes
1 and 11
2 and 11
3 and 4
3 and 44
4 and 44
55 and 66
1 and 3, 4, 44, 55, or 66
No
2 and 3, 4, 44, 55, or 66
3 and 1, 2, 11, 55, or 66
4 and 1, 2, 11, 55, or 66
Any stator lead and ground on stator
housing or frame laminations
Figure 5-7 Continuity Test Results on a Good Stator
(single-phase)
Leads Continuity
1 and 4
Yes
2 and 5
3 and 6
7 and 10
8 and 11
9 and 12
55 and 66
1 and 2, 3, 7, 8, or 9
No
1 and 55
Any stator lead and ground
Figure 5-8 Continuity Test Results on a Good Stator
(three-phase)
8. If the resistance test proves inconclusive, use a
megohmmeter to test the stator as described in the
next step.
Note: Because ohmmeter accuracy varies,
resistance readings are approximate
readings. Take readings of the rotor and
stator at room temperature.
Note: Make sure that all stator leads are
disconnected before running the
megohmmeter test.
9. Use a megohmmeter to determine whether the
stator is shorted to ground.
a. Apply 500 volts DC to any stator lead and the
stator frame. Perform the megohmmeter test
following the instructions of the megohmmeter
manufacturer.
b. Repeat the test o n the other stator leads until
each coil is tested.
Note: A reading of approximately 500 kOhms
(1/2 megohm) and higher indicates a
good stator.
c. Repair or replace the stator if any reading is
less than approximately 500 kOhms. A
reading of less than 500 kOhms indicates
deterioration of the winding insulation and
possible current flow to ground.
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