TROUBLE SHOOTING
EN / W-SQ20 for mobile applications / April 2010
33
5.3
SPECIAL PROCEDURES ALTERNATOR
5.3.1
Automatic Voltage Regulator (AVR)
The voltage regulator has a ±2% voltage precision in the
machine working range with distortion free loads.
The phase voltage can be adjusted by trimmer
“V”
(see
figure 27) from 185 to 290V.
The regulator is equipped with a frequency dependant
excitation limiter; the frequency can be calibrated by
trimmer
“UF”
, which is factory set at 46Hz (56Hz), ±1Hz.
On reaching this frequency, the machine begins to reduce
its voltage until it deactivates for very low frequencies.
A fuse protects the regulator and generator against
overloads and/or faults; a pocket has been provided on the
edge of the board to hold a spare fuse (rapid type 32x6.3
2A).
Another trimmer
“ST”
allows to adapt the regulator to the
generator parameters.
The regulator has been built to suppress the voltage
surges on releasing the load that are below 20% at
nominal load.
AVR SETTINGS
To select the AVR settings access the control board after
removing the cover. Most adjustments are factory set to
ensure satisfactory results in the operating tests on
commissioning. Further adjustments may be necessary to
ensure optimum operation under specific working
conditions.
If the alternator has to operate at 50Hz the jumper
“J”
across the terminals marked “60Hz” has to be left in place,
if it has to operate at 60Hz this jumper should be removed.
The output voltage can be changed by adjusting
potentiometer
“V”
. Take 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 bottom speed protection should first be calibrated. The
voltage reference (orange wires) should be connected:
•
to terminals “0” and “115” for an output voltage
between 100 and 140V (factory setting)
•
to terminals “0” and “230” for an output voltage
between 200 and 280V.
Fig. 27. Automatic Voltage Regulator (AVR)
To increase the range of available voltages by about 15%
use terminal
“Pa”
instead of terminal “0”. Caution: if the
voltage is set any higher than its maximum limit the
generator may be damaged.
Setting the bottom speed 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.
Caution: if the bottom 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.
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.
5.3.2
Residual voltage check / excitation
procedure (flashing)
When residual magnetism disappears there is no residual
voltage. Residual magnetism can disappear after the
generating set being out of service for a long period or a
short circuit. This can be solved by exciting the exciter field
coil directly, disconnecting the AVR first. Put 12 Volt
directly over the electronic regulator terminals taking
polarity into account.
