Sincro SK 400 Manuel D'instruction Et De Maintenance page 29

7.3 Troubleshooting
FAULT
NO VOLTAGE
LOW VOLTAGE
HIGH VOLTAGE
VOLTAGE
OSCILATIONS
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POSSIBLE REASON
Faulty AVR
Faulty rectifi er bridge AND/OR surge
suppressor
Faulty stator exciter
Main winding fault
Demagnetized machine
Broken connections
Reference voltage is not set at desired
value
Under-frequency protecton not properly
adjusted
Engine speed low
Faulty AVR
Reference voltage is not set at desired
value
Sensing supply open circuit
Faulty AVR
AVR stability incorrectly set
Engine speed unstable
Faulty AVR
CHECK / REMIDY
•
Check the fuse
•
Replace the AVR
•
Check rectifi er bridge
•
Check if the stator/rotor exciter
circuit is open
•
Check stator/rotor windings
resistances
•
Check stator/rotor
insualtion resistance
•
Excite the alternator by applying a
6-12 volt current across the exciter
terminals for a second, respecting
the polarities. (engine is running)
•
Check all connections
•
Adjust voltage with potentiometer
«V» on the AVR;
•
Check / adjust, the value of under-
frequency protection (47Hz for 50Hz
nominal frequency)
•
Check the engine speed (voltage
frequency)
•
Replace the AVR
•
Adjust voltage with potentiometer
«V» on the AVR
•
Check the sensing connections
•
Replace the AVR
•
Adjust stability with ST trimmer
•
Check with the frequencymeter
if there are oscilations in engine
speed
•
Replace the AVR
ENGLISH
windings
29