17
2016.06 / h
Electric Power Generation
Installation and maintenance
R450
A.V.R.
4531 en -
4.3 - Electrical faults
Fault
Action
Measurements
Check/Cause
No voltage at
no load on
start-up
Connect a new battery
of 4 to 12 V to terminals
F- and F+, respecting
the polarity, for 2 to 3
seconds
The alternator builds up and its
voltage is still correct when the
battery is removed
- Lack of residual magnetism
The alternator builds up but its
voltage does not reach the rated
value when the battery is removed
- Check the connection of the voltage
reference to the AVR
- Faulty diodes
- Armature short-circuit
The alternator builds up but its
voltage disappears when the
battery is removed
- Faulty AVR
- Field windings disconnected
- Revolving field coil open circuit. Check the
resistance
Voltage too
low
Check the drive speed
Correct speed
- Check the AVR connections and settings
(AVR faulty)
- Field windings short-circuited
- Rotating diodes burnt out
- Revolving field coil short-circuited
- Check the resistance
Speed too low
Increase the drive speed
(Do not touch the AVR voltage pot. (P1)
before running at the correct speed)
Voltage too
high
Adjust AVR voltage
potentiometer
Adjustment ineffective
- Faulty AVR
- 1 faulty diode
Voltage
oscillations
Adjust AVR stability
potentiometer
If no effect: try normal/fast
recovery modes
- Check the speed: possibility of cyclic
irregularity
- Loose connections
- Faulty AVR
- Speed too low when on load
(or U/F knee-point set too high)
Voltage
correct at no
load and too
low when on
load (*)
Run at no load and
check the voltage
between F+ and F- on
the AVR
Voltage between F+ and F-
AREP/PMG < 10 V
- Check the speed
(or U/F knee-point set too high)
Voltage between F+ and F-
AREP/PMG > 15 V
- Faulty rotating diodes
- Short-circuit in the revolving field coil.
Check the resistance
- Faulty exciter armature
(*) Caution:
For single-phase operation, check that the sensing wires coming from the AVR are correctly connected to
the operating terminals.
Voltage
disappears
during
operation (**)
Check the AVR, the
surge suppressor, the
rotating diodes, and
replace any defective
components
The voltage does not return to the
rated value
- Exciter winding open circuit
- Faulty exciter armature
- Faulty AVR
- Revolving field coil open circuit or
short-circuited
- Overload (see LED)
(**) Caution:
Internal protection may be activated (overload, open circuit, short-circuit)
Caution: After operational testing or
troubleshooting, replace all access
panels or covers.
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