9-10
Open or Shorted Test:
To test for open windings,
set the ohmmeter on the highest resistance scale.
Place the test prods on the slip rings as shown in
Figure 9-8. The ohmmeter should indicate continu-
ity between the slip rings of approximately 19 to 27
ohms. A high resistance reading indicates a poor
connection or an open winding. Check the connec-
tion between the slip rings and rotor lead wires. Re-
place the rotor if a winding is open.
To test for a shorted winding, set the ohmmeter on
the lowest scale. Place the test prods on the slip
rings as shown in Figure 9-8. A reading of less than
17 ohms at 77
°F (25°C) indicates shorted windings.
Replace the rotor if a winding is shorted.
Open or shorted tests can also be performed by re-
moving the P4 plug from the regulator J4 connector
and measuring across the P4-9 and P4-10 connec-
tions. If an abnormal reading is measured, recheck
by measuring at the collector rings.
If the rotor tests good proceed to
Stator Test,
follow-
ing.
Stator Test
The stator can be tested for grounded or open wind-
ings using an ohmmeter. Testing for shorted wind-
ings requires a digital type ohmmeter that can read
to within 0.01 ohms. Figure 9-9 on Page 9-11 shows
the stator removed from the generator for testing.
The stator can be tested without removing it from
the generator.
To perform the stator test, carefully remove both
connector plugs from the stator.
Ground Test:
Set the ohmmeter for the highest re-
sistance scale and then connect one test prod to the
generator housing (or stack, if stator is removed).
Touch the other test prod (see Figure 9-9 on Page
9-11) to the terminals specified in Table 9-1 on Page
9-11. A reading of less than one megohm indicates
a ground. Replace a grounded stator with a new
stator.
ES1765-1s
ROTOR
SLIP
RINGS
FIGURE 9-8. OPEN OR SHORTED ROTOR TEST
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