Onan MJA Series Service Manual page 107

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REVO L V IN G FTEL D GKN ERA T O R f . 0 5
TROUBLE SHOOTING CHARTlO, REVOLVING FIELD GENERATOR
TRO'UBLE
PROBAB.L$. CAUSE
REMEDY
. Engine runs but volt-
Residual magnetism gone See Sect 4. 3.1 for
age won't build up trouble shooting.
Dead short in load. Inspect load and cor­
rect.
Magneciter defective, See Trouble..;Sbooting-
Chart 11 -Magneciter
Open circuit,ground or Test as per Sect 4.3.2
short in stator.
Replace
if
necessary .
Open circuit, ground or Test as per Sect 4.3.2
short in revolving field. Replace
if
necessary .
Current unsteady but
Loose connection .
Clean and tighten Con-
engine speed not nections.
fluctuating
Poor brush contact.
Reseator replace
brushes. Clean Slip
rings .
Frequency drops under Low engine power.
'See Trouble..;ShoOting;
heavy load
Chart 1 -Engine
Poor governor adjust- Adjust engine gover­
ment.
nor Sect 3. 4
Voltage drops under Defective Magneciter.
See Trouble-Shooting
hea vy load, little
Chart
11 -
Magneciter
fre.quency change.
Generator won't de-
Unbalanced load on lines. Adjust loa d.
liver rated current.
Defective Magneciter.
See Trouble-Shooting
Chart ll-Magneciter
Defective field windings. Test and replace if
defective
Generator overheats. Overloaded.
Reduce Load.
Partial short in load.
Correct short.
Poor ventilation.
Increase ventilation,
..