TP-6053 7/04 39Section 7 Generator Troubleshooting
5. Check the main field for a grounded condition by
using a megohmmeter. Apply 500 volts DC to
either field lead and the main field frame. Follow
the instructions of the megohmmeter’s
manufacturer when performing this test. See
Figure 7-12. A reading of approximately
500 kOhms (1/2 megohm) and higher indicates the
main field is good. A reading of less than
approximately 500 kOhms indicates the
deterioration of the winding insulation and possible
current flow to ground. Repair or replace the main
field.
F+
F--
AC
AC
AC
5588712
1
2
3
4
5
6
7
1. Main field (rotor)
2. Stator windings
3. Rectifier module
4. Shaft connection
5. Megohmmeter
6. Armature
7. Exciter field
Figure 7-12 Megohmmeter Connections on Main
Field
7.9 Stator
The stator consists of a series of coils of wire laid in a
laminated steel frame. The stator leads supply voltage
to the AC load and exciter regulator.
Leads 1, 2, 3, and 4 are the generator output leads.
Leads 33, 44, and 55 are the voltage regulator supply
and sensing leads. The output of leads B1 and B2 are
rectified by BR1 to supply the control voltage. BR1 is
located on the controller circuit board.
Prior to testing, inspect the stator for heat discoloration
and visible damage to the housing lead wires or
exposed and varnished areas of the frame laminations.
Be sure the stator is securely fastened in the stator
housing.
The stator produces electrical output (AC) as the
magnetized main field rotates within the stator windings.
Test the condition of the stator according to the following
procedure. Refer to the schematic in Figure 7-13 when
performing the following tests.
Stator Test Procedure
1. Check the generator output lead connections. See
Section 10, Voltage Reconnection and Wiring
Diagrams.
2. Disconnect all the stator leads to isolate the
windings. To c heck the stator continuity, set the
ohmmeter on the R x 1 scale. Contact the red and
black ohmmeter leads; adjust the ohmmeter to
zero ohms. Check the stator continuity by
connecting the meter leads to the stator leads as
shown in Figure 7-13. Perform the stator tests on
all the stator windings. See Figure 7-14.
3. Contact the ohmmeter leads and readjust the
ohmmeter to zero ohms. Check the cold
resistance of the stator windings by connecting the
meter leads to the stator leads 1 and 2, 3 and 4,
B1 and B2, etc. See Section 1, Specifications, for
the stator resistance values. Replace the stator if
readings do not fall within the specified value.
Note: The stator resistance will vary directly with
increased temperature.
F+
F--
AC
AC
AC
5588713
F1 F2
33 3
55 44
4
12B1 B2
1
2
3
4
5
6
1. Main field (rotor)
2. Stator windings
3. Rectifier module
4. Ohmmeter
5. Armature
6. Exciter field
Figure 7-13 Stator Ohmmeter Connections
Between Leads Continuity
1 and 2
3 and 4
33 and 44
33 and 55
B1 and B2
1 and 3, 4, 33, 44, 55
1 and 55, B1, and B2
4 and B1 and B2
55 and B1 and B2
Any stator lead and ground
Yes
Yes
Yes
Yes
Yes
No
No
No
No
No
Figure 7-14 Stator Continuity
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