TROUBLE SHOOTING
36
Copyright © 2008 Mastervolt / December 2008 / Whisper 12 Ultra - Three phase for mobile applications/ EN
5.3
SPECIAL PROCEDURES ALTERNATOR
5.3.1
Automatic voltage regulator
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 25) from 185 to 290V.
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 20x5
3.15A).
Another trimmer
“ST”
(stability) allows adapting 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 replaced.
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.
Fig. 25. Automatic Voltage Regulator (AVR)
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 load.
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.
Fig.26: Residual voltage check / excitation procedure.
When using the starter battery fuse it and limit the current
with a 30 Ohm resistor. Flashing can be done while the
engine is running and the wiring is connected. When a
variac (variable power supply) is available one should be
able to control the voltage manually.
CAUTION
If the starter set battery is used for exciting
one must take care. A short circuit can cause
heavy sparking, fire and injuries.
When external excitation does not bring back voltage, the
rotating rectifier diodes should be tested and a winding
resistant test should be executed.
