6.4.5 RD2 AVR
The AVR controls the generator voltage. The AVR is
used to keep a constant voltage when the load and
machine parameters vary. The AVR requires a so-called
sensing connection; a power supply from a specific
circuit (AUX); an output to the exciter (+/-).
The RD2 board is a digital controller that allows you to
select the three-phase sensing (the regulator will keep
constant the average of the 3 voltages detected) or
single-phase sensing. The selection is made by dip-
switch.
In case of unbalanced or distorted load, voltage
regulation accuracy could be reduced.
A frequency control progressively reduces the generator
excitation when the drive engine speed drops below a
pre-set, adjustable threshold preventing over-excitation
at low operating speeds and abating the load engage
effects on the engine.
In conclusion the regulator reaction time can be
modulated to eliminate any voltage instability that may
arise.
The regulator has a dip-switch for the selection of the
working frequency. Set the dip switch (50 / 60Hz) of
the AVR board, depending on the operating frequency
(50Hz ON, 60Hz OFF).
Voltage setting: first, select the type of sensing (three-
phase or single-phase) through the dip-switch. Then
turn, moving it to the ON position, the dip-switch that
shows the voltage closest to the desired value (which
must be consistent with the connection made).
Turn ON the dip-switch:
"115" if connected to a sensing
•
and 130V
"230" if connected to a sensing
•
and 245V.
• "400" if connected to a
sensing
and 460V.
• "480" if connected to
a sensing
and 520V.
The output voltage can be changed by adjusting
potentiometer "V". Run the generating set to its nominal
speed and turn until the required voltage is obtained.
If a small variation in speed causes a change in
voltage, then the under speed protection should first be
calibrated.
If the voltage is set any higher than its
maximum limit the generator may be
damaged.
WARNING!
Stability adjustment: if on load voltage fluctuations
are experienced adjust potentiometer "ST", which
modulates the reaction time of the regulator to external
inputs, thereby eliminating any instability in the
alternator-load system.
If the adjustment via potentiometer ST does not prove
to be sufficient, is possible also to use the dip-switch
ST+ / ST: moving it to the ON position (ST +) stability
increases.
If the under speed is set at too low a
frequency, the generator may be damaged.
On the other hand, too high a frequency can
cause voltage drops with high loads.
WARNING!
26
Setting of the under speed protection at 50 (60)
Hz: start up rotation of the generating set adjusting it to
obtain a frequency of 46 (56)Hz. Turn trimmer "UF" until
the voltage begins to drop. Restore nominal speed.
Remote voltages adjustment :
1) with potentiometer:
POT (and make sure the dip switches EXT-VOLT is
turned OFF).
Wire the potentiometer (5kOhm, 3W) to the terminals
"EXT POT". Run the generating set to its nominal speed
and adjust the external potentiometer and trimmer "V" to
obtain the desired voltage. The external potentiometer
has the effect of increasing the voltage value set by the
"V" trimmer.
2) Connection with controller or cosf regulator:
ON the dip-switch EXT-VOLT (and make sure the dip
switches EXT-POT is turned OFF). The AVR regulator
accepts voltage analogic input (0-10VDC, observe
polarity shown in figure) for remote voltage adjustment.
To set the system, follow this procedure:
- Decrease the voltage by turning the "V" trimmer
counter-clockwise;
- Apply half the control voltage at the "EXT pot" terminals
(5 VDC);
- Act on the "V" trimmer to bring the voltage to the
nominal value;
in this way, the external controller can increase or
decrease the output voltage.
In case the remote voltage adjustment is not used, turn
OFF the dip-switches EXT-POT and EXT-VOLT. Pay
attention not to turn ON both the dip-switches.
voltage between 100
voltage between 185
voltage between 340
voltage between 440
6.4.6 Wiring diagrams for different circuits
In the appendix of this manual there are diagrams for
connections other than the factory star-series connec-
tion (standard unless otherwise specified on order).
Turn ON the dip-switch EXT-
V ST UF
Phase
Frequency
Dip-switch
Dip-switch
V ST UF
Off
A
B
C
On
V ST UF
Off
On
CW
Voltage
Increase
A
B
A
B
C
V
CCW
Voltage
Off
Off
Decrease
V ST UF
On
On
CW
Voltage
Voltage
CW
Stability
CW
increasing
Increase
Voltage
Decrease
Increase
V
CCW
Voltage
Decrease
ST
CCW
Stability
V
Voltage
CCW
Voltage
Increase
A
decreasing
Decrease
Off
CW
Stability
On
Decrease
Underfrequency
ST
protection limit
Corner
CW
CCW
Stability
increasing
CW
Increase
Frequency
CW
Stability
Voltage
Increase
Increase
Decrease
Corner
Underfrequency
UF
V
CCW
CCW
Voltage
Corner
CW
Frequency
protection limit
ST
CCW
Decrease
Frequency
Stability
Decrease
decreasing
Increase
Increase
Corner
UF
CCW
Frequency
CW
Decrease
Stability
Decrease
Corner
CW
ST
CCW
Stability
Frequency
Increase
Increase
Corner
UF
CCW
Frequency
Corner
CW
Frequency
Decrease
Increase
Corner
UF
CCW
Frequency
Decrease
Turn
Off
On
V ST UF
Voltage
Dip-switch
Off
On
-
+
L
N
A
B
Off
On
Polarity of EXT. Voltage
CW
Voltage
-
+
Increase
L
C
N
-
+
L
N
Off
V
CCW
Off
Voltage
On
Decrease
On
Polarity of EXT. Voltage
0V (-)
Polarity of EXT. Voltage
Stability
CW
Stability
decreasing
0-10V (+)
Decrease
Off
On
ST
CCW
-
Stability
+
Stability
Off
L
B
C
N
Increase
increasing
On
0V (-)
0-10V (+)
Connection with controller,
Observe polarity:
Corner
CW
Polarity of EXT. Voltage
0V (-)
Frequency
0-10V (+)
Increase
Corner
UF
Off
CCW
Frequency
On
Decrease
0V (-)
0-10V (+)
Off
On
-
+
C
Polar
Off
On
0V
0-10V