Lincoln Electric SVM194-A 42TROUBLESHOOTING and REPAIRF-42, Static Tests, Dynamic Tests

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F-42TROUBLESHOOTING AND REPAIRF-42

EXCITER ROTOR RESISTANCE AND GROUND TESTS PROCEDURE

(Exciter / Auxiliary Power Alternator) (continued)

FIGURE F.2 – LEAD LOCATION

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PROCEDURE

"Static" Tests:

1. Turn the engine off.

2. Remove the round cover from the exciter / aux- iliary power alternator.

3. Locate and label the leads connected to the rotor brush holder assembly. Remove the leads. This will electrically isolate the rotor windings.

4. Using the ohmmeter, check the rotor winding resistance across the slip rings. Normal resis- tance is approximately 41.5* ohms, at 77°F. (25° C.) See Figure F.2

5. Measure the resistance to ground. Place one meter probe on either of the slip rings. Place the other probe on any good unpainted chassis ground. The resistance should be very high, at least 500,000 (500k) ohms.

6. If the resistance measurements are not as specified the rotor may be faulty and should be replaced.

If these resistance values are normal, continue testing, using the dynamic rotor resistance and ground test.

"Dynamic" Tests:

(Also referred to as flying resistance test)

This test checks for faults in the rotor winding, while these windings are being stressed by the mechanical forces encountered during normal operation.

NOTE: This test is best performed with a good quality analog type ohmmeter. Many digital meters will not provide stable or accurate resistance readings while the rotor is spin- ning.

This test requires that the brushes and slip rings are clean, in good condition, and are properly seat- ed.

Perform the Brush and Slip RIng Service Procedure if necessary.

CLASSIC® 300D & 300G