Section 3
DESCRIPTION & COMPONENTS
3. Repeat Step 1 at Pin Location 8 (Wire 55) and Stator Lead 11.
For the following steps (4 through 6) an additional paper clip (or similar item) will be needed:
4.Insert a paper clip into Pin Location 3 (Wire 55A). Connect the red tester probe to the paper clip. Insert additional paper clip into Pin Location 6 (Wire 2). Connect the black tester probe to this paper clip. Refer to Steps 5a through 5c of “TESTING ALL STATOR WINDINGS TO GROUND” on the previous page.
5.Insert a paper clip into Pin Location 3 (Wire 55A). Connect the red tester probe to the paper clip. Insert additional paper clip into Pin Location 8 (Wire 55). Connect the black tester probe to this paper clip. Refer to Steps 5a through 5c of “TESTING ALL STATOR WINDINGS TO GROUND” on the previous page.
6.Insert a paper clip into Pin Location 6 (Wire 2). Connect the red tester probe to the paper clip. Insert the additional paper clip into Pin Location 8 (Wire 55). Connect the black tester probe to this paper clip. Refer to Steps 5a through 5c of “TESTING ALL STATOR WINDINGS TO GROUND” on the previous page.
Rotor Insulation Resistance Test
Before attempting to test rotor insulation, the brush holder must be completely removed. The rotor must be completely isolated from other components before starting the test. Attach all leads of all stator windings to ground.
1.Connect the red tester lead to the positive (+) slip ring (nearest the rotor bearing).
2.Connect the black tester probe to a clean frame ground, such as a clean metal part of the rotor shaft.
POSITIVE (+)
TEST LEAD
Figure 3-10. – Testing Rotor Insulation
3.Turn the tester switch OFF.
4.Plug the tester into a 120 volts AC wall socket and set the volt- age switch to “1500 volts”.
5.Turn the tester switch “On” and make sure the pilot light has turned on.
6.Observe the breakdown lamp, then turn the tester switch OFF.
DO NOT APPLY VOLTAGE LONGER THAN ONE (1) SECOND.
If the breakdown lamp came on during the one (1) second test, cleaning and drying of the rotor may be necessary. After cleaning and drying, repeat the insu- lation breakdown test. If breakdown lamp comes on during the second test, replace the rotor assembly.
Cleaning the Generator
Caked or greasy dirt may be loosened with a soft brush or a damp cloth. A vacuum system may be used to clean up loosened dirt. Dust and dirt may also be removed using dry,
*CAUTION: Do not use sprayed water to clean the generator. Some of the water will be retained on generator windings and terminals, and may cause very serious problems.
Drying the Generator
To dry a generator, proceed as follows:
1.Open the generator main circuit breaker. NO ELECTRICAL LOADS MUST BE APPLIED TO THE GENERATOR WHILE DRYING.
2.Provide an external source to blow warm, dry air through the generator interior (around the rotor and stator windings. DO NOT EXCEED 185° F. (85° C.).
3.Start the generator and let it run for 2 or 3 hours.
4.Shut the generator down and repeat the stator and rotor insula- tion resistance tests.
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