2018.01 / g
8
Electric Power Generation
Installation and maintenance
R150
AVRs
5384 en -
7 - TROUBLESHOOTING CHART
Symptom Cause Action
No voltage
build-up
Fuse blown Check and replace
Low residual voltage across U
and N terminals
If the generator’s residual voltage at rated speed
is less than 2.5 VAC (L-N), disconnect the AVR
and connect a 24 VDC battery, keeping F1 as
positive and F2 as negative.
Connecting a freewheel diode (BY 127) across
the eld with the diode cathode to F1 and the
anode to F2 during eld ashing will help restore
the residual voltage.
WARNING:
Remove the diode (BY-127) after eld ashing.
The 24 V battery positive terminal must only be
connected to F1 and the negative to F2.
Swapping the connection will cause diode BY127
to explode instantly.
Incorrect wiring Check wiring
Rotating diodes and/or fuse
failed
Check and replace
Voltmeter on the front
defective
Check and correct
AVR defective
(repeated fuse blowing)
Replace after performing a static test
Earthed exciter eld Check and correct
High voltage
build-up
Loose or missing connection
to AVR U terminal
Check and correct
AVR defective Perform a static test and replace if necessary
Low voltage
build-up
Low prime mover speed Check and correct
Sensing loss in circuit Check and correct
AVR defective Replace the AVR
Voltage oscillation Incorrect stability
potentiometer sealing
Turn clockwise until hunting stops
Prime mover speed hunting Check and adjust the controller
Load hunting, uctuates
rapidly
Check and correct
High percentage of non-linear
loads
Check and reduce the non-linear load
High reactance in generator
(during non-linear loading)
Consult the generator manufacturer
Incorrect
regulation
The exciter eld’s requirement
is higher than 105 VDC
Wrong selection or very low P.F. load. Check and
correct.
Prime mover speed drops too
much when on load (kW load)
Adjust the controller and reduce the active load
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