Rotor Resistance And Ground Test Procedure (Dynamic) - Lincoln Electric Cross Country 300 Service Manual

LINCOLN ELECTRIC
ROTOR RESISTANCE AND GROUND TEST PROCEDURE (DYNAMIC)
(Also referred to as flying resistance test)
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
7/16" Nutdriver
Volt/Ohmmeter
Wiring Diagram
TEST PROCEDURE
NOTE: This test requires that the brushes and slip rings are clean, in good condition and are properly
seated.
1. Perform the Brush And Slip Ring Service Procedure.
2. Turn off the engine on the Cross Country 300 machine.
3. Perform the Case Cover Removal Procedure.
4. Using a 7/16" nutdriver, label and disconnect leads 201 and 200B from the field capacitor. See
Figure F.41. See Wiring Diagram.
5. Using an ohmmeter, connect the ohmmeter to leads 201 and 200B and insulate the connections.
See Wiring Diagram.
6. Start the engine and run at high idle speed (1860-1890 RPM). The resistance should read
approximately 25 ohms.
7. Shut off engine and move one of the ohmmeter leads to a good clean chassis ground.
8. Start the engine and run at high idle speed (1860-1890 RPM). The resistance should read very high,
at least 500,000 (550k) ohms.
9. 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, the rotor may be faulty.
10. If faulty, perform the Stator, Rotor And Shaft Assembly Removal And Replacement Procedure.
11. Using a 7/16" nutdriver, connect leads 201 and 200B to the field capacitor. See Wiring Diagram
12. Perform the Case Cover Replacement Procedure.
*NOTE: The resistance of the windings will change with temperature. Higher temperatures will
produce higher resistances and lower temperatures will produce lower resistance.
Cross Country™ 300 Service Manual
82