3-4
3.3 A-C BRUSHLESS GENERATOR
(MAIN ALTERNATOR)
INDICATION/
REFERENCE
TROUBLE
POSSIBLE CAUSES
SECTION
No voltage
Loss of residual magnetism in exciter field
4.5.1.g
Circuit breaker tripped
Check
Open in stator windings
4.5.2
Open or short in rotating rectifiers
4.5.1.c
Short circuited
4.5.2
Open in alternator field
4.5.2
Shorted exciter armature
4.5.2
Low voltage
Low engine speed
4.3.4
Excessive load
Check
High resistance connections --- connections
warm or hot
Tighten
Shorted field
4.5.2
Fluctuating voltage
Fluctuating speed
4.3.4
(May be indicated by
Irregular speed of engine
Engine Manual
flickering lights)
Loose terminal or load connections
Tighten
Defective bearing causing uneven air gap
4.5.1.b
High voltage
Excessive engine speed
4.3.4
Overheating
Generator overloaded
Check
Clogged ventilating screens
Clean
High temperature surrounding generator
4.3.1
Insufficient circulation
4.3.1
Unbalanced load
Balance
Dry bearing
4.5.1.b
Mechanical Noise
Defective bearing
4.5.1.b
Rotor scrubbing on stator
4.5.1.b
Loose laminations
4.5.2
Loose or misaligned coupling
4.5.2
Generator frame
Static charge
Check ground
produces shock
to frame
when touched
Grounded armature of field coil
4.5.2
