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PART 1
GENERAL INFORMATION
SECTION 1.5
TESTING, CLEANING AND DRYING
TESTING ALL STATOR WINDINGS TO GROUND:
1. Disconnect Stator Output Leads 11 and 44 from the
generator main line circuit breaker.
2. Disconnect Stator Output Leads 2 and 6 from the
capacitor located on the end of the stator assembly.
3. Remove Stator Output Leads 22 and 33 from the neutral
connection and separate the two leads.
4. Connect the terminal ends of Wires 11, 22, 33, and 44
together. Make sure the wire ends are not touching any
part of the generator frame or any terminal.
5. Connect the red test probe of the Hi-Pot tester to the
joined terminal ends of Stator Leads 11, 22, 33, and 44.
Connect the black tester lead to a clean frame ground
on the stator can. With tester leads connected in this
manner, proceed as follows:
a. Turn the Hi-Pot tester switch OFF.
b. Plug the tester cord into a 120 volt AC wall
socket and set its voltage selector switch to
“1500 volts”.
c. Turn the tester switch ON and observe the
breakdown lamp on tester. DO NOT APPLY
VOLTAGE LONGER THAN 1 SECOND. After
one (1) second, turn the tester switch OFF.
6. Connect the terminal ends of Wires 2 and 6 together.
Make sure the wire ends are not touching any part of
the generator frame or any terminal.
7. Repeat Step 5.
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.
ROTOR INSULATION RESISTANCE TEST
(8-10 KW)
No test available.
ROTOR INSULATION RESISTANCE TEST
(12-20 KW)
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.
3. Turn the tester switch OFF.
4. Plug the tester into a 120 volts AC wall socket and set
the voltage 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.
POSITIVE (+)
TEST LEAD
Figure 9. Testing Rotor Insulation (12-20kW)
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. Disconnect all Wires 6 from the voltage regulator.
3. Provide an external source to blow warm, dry air through
the generator interior (around the rotor and stator wind-
ings. DO NOT EXCEED 185° F. (85° C.).
4. Start the generator and let it run for 2 or 3 hours.
5. Shut the generator down and repeat the stator and rotor
insulation resistance tests.
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