Troubleshooting - Sincro SK225 SM Manuel D'utilisation Et De Maintenance

7.3 Troubleshooting

FAULT POSSIBLE REASON
Faulty AVR
Faulty rectifi er bridge and/or surge suppres-
sor
Faulty stator exciter
NO VOLTAGE
Main winding fault
Demagnetized machine
Broken connections
Reference voltage is not set at desired value
Under-frequency protecton not properly
adjusted
LOW VOLTAGE
Engine speed low
Faulty AVR
Reference voltage is not set at desired value
HIGH VOLTAGE Sensing connection open circuit
Faulty AVR
AVR stability incorrectly set
UNSTABLE
Engine speed unstable
VOLTAGE
Faulty AVR
For more questions contact the Sincro After Sales Service.
CHECK / REMEDY
• check the fuse
• replace the AVR
• check rectifi er bridge
• check if the stator exciter circuit is open
• check stator/rotor windings resistances
• check stator/rotor windings insulation
resistance
• excite the alternator by applying a 6-12
voltage 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-frequen-
cy protection for 50Hz (60Hz) nominal
frequency.
• check the engine speed (voltage frequen-
cy)
• replace the AVR
• adjust voltage with potentiometer «V» on
the AVR
• check the sensing connections
• replace the AVR
• check the correct Dip switches position,
adjust stability with ST trimmer
• check with the frequencymeter if there
are oscillations in engine speed
• replace the AVR
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