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SECTION 8 |
Generator Mode - General Information
In Generator Mode, the following input / output connections are made:
• The generator power is connected to the AC Input terminals.
• The AC output terminals are connected to the AC distribution wiring
• The battery is connected to the Battery Input Terminals
• If a parallel external charging source (e.g. charge controller fed from
solar array or another AC charger) is required to charge the batteries,
it should be connected to the auxiliary DC input terminals provided
for connecting external battery charger / charge controller
Important Information on Using Generator
As external AC Input Source
The AC output voltage of a generator is proportional to its rotational
speed (RPM – Revolutions Per Minute) and to the amount of excitation
current fed to its field windings. The frequency of the AC output voltage
produced by the generator is proportional to the RPM of the engine and
the number of poles used in the generator. The RPM of the generator
is controlled and kept constant by the mechanical governor installed
on the engine that is driving the generator. The output voltage of the
generator is controlled by its electrical voltage regulator that controls
the excitation current fed to its field windings. When an electrical load is
applied to the generator, its output voltage tends to drop and the speed
of the engine also tends to drop leading to drop in the output frequency
and additional drop in the output voltage. The drop in the RPM of the
engine is countered by the engine governor by feeding more fuel to the
engine. The drop in output voltage of the generator is countered by the
voltage regulator of the generator by increasing the current fed to the
field windings. Similarly, when a load is removed from the generator, its
output voltage tends to rise and the RPM of the engine also tends to rise
leading to increase in the output frequency and additional increase in the
output voltage. The increase in the RPM of the engine is countered by
the engine governor by reducing the fuel supply to the engine. The rise in
the output voltage of the generator is countered by the voltage regulator
of the generator by decreasing the current fed to the field windings.
The mechanical governor and electrical voltage regulator have sensitivity
of producing controlling action to correct a deviation of the controlled
parameter. Higher sensitivity tends to produce oscillations around the
controlled value. Hence, when these devices try to control very fast
moving parameters, they will produce larger oscillations before settling
down. The voltage regulator will tend to produce high voltage transients
during this time. These symptoms are seen during the start up and
shut down of the engine-generator.
For 60 Hz frequency of AC voltage, the engine speeds should be
3600 RPM for 2 pole, 1800 RPM for 4 pole and 1200 RPM for 6 pole
generators.
When a generator is started, it is cold and it starts from 0 RPM and
reaches the rated RPM within a finite time. Thus, during the initial period
of ramping up from 0 RPM to the rated RPM, its frequency and output
voltage will be fluctuating due to the regulating action of the mechanical
governor and the electrical voltage regulator. As this happens in a very
short duration, during this period, the output frequency will fluctuate
and the output voltage will also fluctuate and will contain a lot of high
voltage transients that are produced by the extremely fast regulating
50 | SAMLEX AMERICA INC.
Operation
actions of the mechanical governor and the voltage regulator. These
voltage and frequency fluctuations and high voltage transients can
damage the AC loads that are fed from the generator. Also, the engine
needs some time to warm up and stabilize in its mechanical operation.
normally, the engine - generator should be warmed up for at least
10 minutes before loading the generator.
The same fluctuations in frequency and voltage and appearance of high
voltage transients will be seen at the output of the generator at the time
of shutting down the engine.
!
CAUTIon!
In view of the above, it is very important that all AC
loads on the output of the generator are switched
on only after around 10 minutes of generator
starting to ensure that the engine and generator
have warmed up sufficiently and that the generator
is providing stable frequency and well regulated,
cleaner, transient free output voltage to prevent
damage to the AC loads / G4 series Inverter Charger.
Similarly, the AC loads should be disconnected first
before the engine is shut down.
!
ATTENTION!
C'est vraiement important que toutes les charges
CA qui sont branchées au générateur sont mises
en marche 10 minutes après que le générateur a
démarré. Cela permet que le moteur et le générateur
sont bien réchauffé et que le générateur fourni
une fréquence stable et une tension de sortie
sans transition, bien reglé/propre qui empêche
d'endommager les charges CA /le G4. Sembablement,
les charges CA devraient être déconnecter avant que
le moteur soit fermé.
operation In Generator Mode
This mode of operation is selected through the Settings Menu (sCreen 1,
page 40).
This mode is recommended to be used when the AC input source is a
generator. As explained above, the voltage output of a generator is likely
to have wider frequency fluctuations due to load variations as compared
to very low frequency variations in the utility / grid AC power.
The G4 Series comes preset in the "Utility Mode" (Generator Mode
disabled). As the frequency of the utility / grid AC power does not vary
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