Troubleshooting - Sincro DC Serie Manual De Uso Y Mantenimiento

7.3 Troubleshooting

FAULT POSSIBLE REASON
Faulty AVR
Faulty rotating rectifier bridge and/or surge sup-
pressor
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.
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CHECK / REMEDY
• check the fuse
• replace the AVR
• check rotating rectifier 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-frequency
protection for 50Hz (60Hz) nominal frequen-
cy.
• check the engine speed (voltage frequency)
• 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