FIGURE 8-12. TESTING ROTOR FOR OPENS
OR SHORTS
Stator Test
The stator
may
be
tested for grounded
or
open
windings by using
an
ohmmeter. Testing for
shorted windings requires a digital ohmmeter that
can read
to
within 0.01 ohms.
Figures 8-13 and
8-14
show
the stator removed
from the generator for testing. However,
it
may
be
tested without removing
it
from the generator. Re-
move the control panel
to obtain access to the
specified lead wires during testing.
Ground Test:
To
test for grounds, disconnect the
transformer and stator leads
listed below:
• Stator leads
T1
and
T3
from TB1
• Stator lead
B1
from A1/P1-1
• Stator lead
01
from VR1/J4-11
8-16
Insulate
or
position the lead wire ends so they
do
not touch the set housing
or
other components
within the control. Set the ohmmeter to its highest
resistance scale, then connect
one
test prod
to
the
generator housing. Touch the other test prod (see
Figure 8-13) to the listed leads individually. A read-
ing less than one megohm indicates a ground. Re-
place a grounded stator with a
new
stator.
Open
or
Shorted Windings Test:
To
test for
opens, disconnect the following leads:
• Stator leads T1, T2, T3 and
T4
from
TB1
• Stator leads
B1
and
B2
from A 1
• Stator leads
01
and
02
from
VR1
Set the ohmmeter to the highest resistance scale.
Connect the test prods (see Figure 8-14}
to
the
generator lead
ends
in pairs: T1/T2, T3/T4, B1/B2,
and
01/02.
The ohmmeter should indicate conti-
nuity between lead ends.
A high resistance reading
indicates an open winding. Replace
an
open stator
with a new stator.
To test
for
shorted windings, use a digital ohmmeter
that reads to within
0.01 ohms. Disconnect the sta-
tor
leads as specified in
the
Open Test section.
Connect the test prods (see Figure 8-14) to the
leads in pairs
as
specified
in
the
Open
Test section.
The readings for lead pairs should be
as
follows
(plus
or
minus 1 0%):
Leads T1/T2: 0.327
ohms
Leads
T3/T
4: 0.327
ohms
Leads B1/B2: 0.058 ohms
Leads
01
/02:
2.089 ohms
A reading less than these values indicates shorted
windings. Replace a shorted stator with a new sta-
tor.
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