Lincoln Electric SAE-300 HE, Service Manual, Page: 33 / 84

LINCOLN ELECTRIC SAE-300® HE Service Manual
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EXCITER ROTOR VOLTAGE TEST PROCEDURE
Service and repair should be performed by only Lincoln Electric factory trained personnel. Unauthorized
repairs performed on this equipment may result in danger to the technician or machine operator and will
invalidate your factory warranty. For your safety and to avoid electrical shock, please observe all safety
notes and precautions detailed throughout this manual. If for any reason you do not understand the test
procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department
for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
TEST DESCRIPTION
This test will determine if the Exciter Rotor Winding is operating at normal voltage.
MATERIALS NEEDED
Volt/Ohmmeter
Wiring Diagram
TEST PROCEDURE
1. Turn off the engine on the SAE-300 HE machine.
2. The engine and generator should be at normal operating temperature for this test. If the machine is
cold, the voltage readings may be slightly higher than specified.
3. Remove the covers from the exciter/auxiliary power alternator by removing the screws securing it.
4. Connect the voltmeter probes to the brush terminals. See Figure F.8 . See Wiring Diagram.
NOTE: On this machine and all other Lincoln Electric DC generator machines, the black exciter lead is
positive and the red lead is negative.
5. Start the engine and place the idle switch in the “HIGH” position.
6. Using a volt/ohmmeter, measure the voltage at the brush terminals. See Wiring Diagram. The
voltage should be 135 to 145 VDC*.
7. Set the RUN/STOP switch to “STOP”.
If the meter reading is normal, this test is complete.
If the voltage measures zero or very near zero, perform the Flashing Voltage Test Procedure and
the Exciter Rotor Resistance and Ground Test Procedure (Exciter / Auxiliary Power Alternator) .
If voltage is higher than specified, the engine RPM may be too high, or there may be voltage
intrusion from one of the higher voltage stator windings to the stator exciter winding. Perform
the Exciter Stator Short Circuit and Ground Test Procedure .
If the voltage is lower than 124, but higher than 6, the engine RPM may be too low, or there may be
problems in the windings or other exciter circuit components or connections. Perform the testing
described below, under the heading “If the voltage measures about 2 to 4 VDC”
If the voltage measures about 2 to 4 VDC, the generator is not building-up to normal output even
though the flashing circuit appears to be functioning normally. This condition could be caused by
one of several failed components or connections. Continue with the following tests.
8. Test the field bridge rectifier.