Rotor Insulation Resistance Test; Cleaning The Generator; Drying The Generator - Generac Power Systems 4451 & 4986 Repair Manual

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
DescRiption & coMponents
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, low-pressure air (25 psi
maximum).
* 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.
section 3
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