Guardian 4389 Repair Manual page 20

SECTION 1.4
TESTING, CLEANING AND DRYING
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 4. Testing Rotor Insulation
Page 18
PART 1
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 termi-
nals, and may cause very serious problems.
DRYING THE GENERATOR
To dry a generator, proceed as follows:
1. Open the generator main circuit breaker. NO ELECTRI-
CAL LOADS MUST BE APPLIED TO THE GENERA-
TOR WHILE DRYING.
2. Disconnect all Wires 4 from the voltage regulator.
3. Provide an external source to blow warm, dry air
through the generator interior (around the rotor and sta-
tor windings. 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.
GENERAL INFORMATION