Rotor Resistance And Ground Test Procedure (Dynamic) - Lincoln Electric Fleet 400 Service Manual

LINCOLN ELECTRIC

ROTOR RESISTANCE AND GROUND TEST PROCEDURE (DYNAMIC)

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 checks for faults in the Rotor Winding, while these windings are being stressed by the mechanical
forces encountered during normal operation.
MATERIALS NEEDED
Volt/Ohmmeter
Wiring Diagram
NOTE: Some digital meters will not provide stable or accurate resistance readings while the rotor is
spinning.
TEST PROCEDURE
1. Turn off the engine on the Fleet 400 machine.
2. Perform the Case Cover Removal Procedure.
3. Perform the Chopper Module Capacitor Discharge Procedure.
4. This test requires that the brushes and slip rings are clean, in good condition and are properly
seated.
5. Perform the Brush and Slip Ring Service Procedure, if necessary.
6. Label and disconnect leads 201 and 200B from the field capacitor and connect an ohmmeter across
the two leads and insulate the connections. See Wiring Diagram.
7. Start the engine. The resistance should read approximately 28 ohms. The resistance of the
windings will change with temperature. Higher temperatures will produce higher resistance and
lower temperatures will produce lower resistance.
8. Shut off engine and move one of the ohmmeter leads to a good clean chassis ground.
9. Restart the engine. The resistance should be very high, at least 500,000 (500k) ohms.
10. If the resistance readings differ significantly from the values indicated, re-check the brushes and the
brush spring tension. If the brushes and slip rings are good, replace the rotor.
11. If all testing is complete, reconnect the leads to the field capacitor.
12. Perform the Case Cover Replacement Procedure.
Fleet™ 400 Service Manual
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