Dead Short, 1St Step And Open Reactor Test Procedures - Lincoln Electric SAE-300 HE Service Manual

LINCOLN ELECTRIC

DEAD SHORT, 1ST STEP AND OPEN REACTOR TEST PROCEDURES

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 procedure tests the operation of the Coarse Current Control Unit (Variable Reactor) and the Series
Field Coils in the Welding Generator.
This procedure should be done if the low end weld output too low, too high, or varies abnormally and the
auxiliary output is normal.
MATERIALS NEEDED
Volt/Ohmmeter
Resistive Load Bank
A Short Length Of Heavy Cable To Short The Output, Or Load Bank With Shorting Contactor
Wiring Diagram
TEST PROCEDURE
1. Turn off the engine on the SAE-300 HE machine.
2. If possible, bring the machine to normal temperature by connecting a load bank and operating the
machine at 100% output (250 amps @ 30 volts) for about 30 minutes.
3. Remove the load; turn the Fine Current / O.C.V. Rheostat to MAXIMUM and the Coarse Current
Control to MINIMUM (Contacts on the insulated steel filler or "Open Reactor").
4. Short the output terminals and check that the machine output is 92 to 117 Amps, at 0.2 to 4 Volts
DC*.
If there is no output at the Min. setting of the output control, there is probably an open circuit in the
series coils or the conductors connecting them. See the Wiring Diagram.
A high output when the reactor is set to Min. would indicate a possible short in the series coils. See
the Wiring Diagram.
5. Begin rotating the coarse current control unit until the output current changes, this is the first step
or first turn of the reactor coil. See Figure F.12. The output should measure 140 to 185 Amps, at
0.2 to 4 Volts DC*.
A slightly high reading in the Min. position, with no clear first step jump in output could indicate that
the contacts are badly worn and the contact fingers, rather than the contacts themselves, may be
making contact with the output control winding. Perform the Coarse Current Control Unit (Variable
Reactor) Inspection and Service Procedure.
No change in the output as the coarse current control unit is slowly increased to the first step would
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