LEROY-SOMER
Installation and maintenance
4276 en- 10.2008/a
R220
A.V.R.
3.3 - Electrical faults
Fault
Action
Effect
Check/Cause
No voltage at
no load on
start-up
Connect a new battery
of 4 to 12 volts to
termináis E- and E+,
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
valué 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
- Main field winding open circuit - check the
resistance
Voltage too
low
Check the drive speed
Correct speed
Check the AVR connections (AVR may be
faulty)
- Field windings short-circuited
- Rotating diodes burnt out
- Main field winding short-circuited - Check
the resistance
Speed too low
Increase the drive speed
(Do not touch the AVR voltage pot. (P2)
before running at the correct speed.)
Voltage too
high
Adjust AVR voltage
potentiometer
Adjustment ineffective
Faulty AVR
Voltage
oscillations
Adjust AVR stability
potentiometer
- Check the speed : possibility of cyclic
irregularity
- Loose connections
- Faulty AVR
- Speed too low when on load (or U/F bend
set too high)
Voltage
correct at no
load and too
low when on
load O
Run at no load and
check the voltage
between E+ and E- on
the AVR
- Check the speed (or U/F bend set too high)
- Faulty rotating diodes
- Short-circuit in the main field. 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 termináis
Voltage
disappears
during
operation
Check the AVR, the
surge suppressor, the
rotating diodes, and
replace any detective
components
The voltage does not return to the
rated valué.
- Exciter winding open circuit
- Faulty exciter armature
- Faulty AVR
- Main field open circuit or short-circuited
A
W arning : after operational testing, replace all access panels or covers.
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