2018.01 / g
7
Electric Power Generation
Installation and maintenance
R150
AVRs
5384 en -
5 - AVR SETTINGS
5.1 - V-TRIM: V
This function is provided for setting the voltage
up to ± 12% of rated voltage by means of a
potentiometer. Turn the potentiometer
clockwise to increase the voltage and vice
versa, once the rated speed has been
reached.
It is also possible to connect an external
potentiometer.
5.2 - UF - Under frequency knee point
setting
This function is provided to protect the
AC generator from sustained low speed
operation through a potentiometer. The AVR
will reduce the voltage in proportion with the
speed below the defined value. The procedure
for setting the UF potentiometer is as follows:
First run the generator at full speed (50 Hz)
and turn the UF potentiometer by a few turns
clockwise, making sure that the voltage does
not increase. Now turn the UF potentiometer
slowly anticlockwise. At a particular point the
red LED glows and the voltage will start to
decrease. Stop turning the potentiometer at
this point and turn the potentiometer clockwise
by two turns after rated voltage is restored.
The factory default setting is 46 Hz.
For 60 Hz operation, the knee point position is
set to 56 Hz.
5.3 - STAB: S
This function is provided to stop voltage
hunting by means of a potentiometer. Turn
clockwise to increase stability (to stop
oscillation). Turning too far clockwise will
result in a sluggish response and possibly
also oscillations.
The factory default setting is slightly
higher than critical damping (around
halfway).
5.4 - EXC LIMIT: OE
This function is provided to protect the Exciter
Field from overexciting by turning a
potentiometer clockwise to increase the
excitation limit. It is factory-set at 105 V. The
red LED lights up when the ceiling has been
reached for more than 10 s.
5.5 - QUADRATURE DROOP
This potentiometer is used to adjust the
voltage droop to balance the reactive load in
parallel operation. Follow the instructions for
connecting the CT (current transformer)
which is essential for this function, as per the
AVR connection diagram.
Turn the potentiometer clockwise to increase
% droop and vice versa.
5.6 - A1&A2 DC VOLTAGE
INPUTS: AC
These accessory terminals A1 and A2 are
used to inject ± 1.0 to 4.5 VDC. The variation
in terminal voltage will be ± 10% of the rated
voltage.
Warning: A “Vishay spectrol model 8”
type screwdriver should be used to adjust
the potentiometer.
6 - AVR CONTROLS
No.
Control
Function
Direction
V
VOLTS
Sets the generator output voltage
Turn clockwise to increase output voltage
UF
UFRO
Sets the Under frequency knee point Turn clockwise to reduce the knee point
S
STAB
Stops voltage hunting
Turn clockwise to increase stability
OE
OVER EXC Sets the overexcitation limit
Turn clockwise to increase the limit
DROOP
DROOP
Sets voltage droop
Turn clockwise to increase the droop
AC
ACC (DC i/p) Used for Auto synchronization
Turn clockwise to increase the gain
