Northern Lights IM1000 Installation Manual - page 9
IM1000 02/13
Electric motors and appliances containing electric
motors usually require up to ten times the running wattage
during starting. A good rule of thumb when working with
motor loads is to take the running wattage of the largest
motor and multiply that by ten. Then add the running
wattage of all the smaller motors, as well as the wattage
of all the other loads. This will add up to your total load.
Determine how much of the total load will be
operating at the same time. If a motor can be wired up at
Northern
Lights
produces
marine and land-based
generator sets that operate at 1500 and 1800 RPM with
ratings from 4.5 kW to 280 kW.
With this broad range of sets to choose from, it is often
diffi cult to determine which is right for your vessel. Begin
the selection process by estimating the electrical load.
After that, you can customize the chosen set to
match your vessel's needs. Modifi cations include single
phase or three phase, 50 cycle output, heat exchanger or
keel cooling, wet or dry exhaust and 12 or 24 volt
starting systems.
It is important to match the correct Northern Lights
generator with your vessel's electrical load. The right
generator is determined by the total wattage of all the
equipment and appliances which will be operated
simultaneously. Selecting a generator that is too small
for the peak load can make it hard to start motors in air
conditioners or water makers, for example. Selecting too
large a generator causes the engine to operate in an overly
cool condition which causes injector and valve carboning,
and the pumping of raw fuel into the exhaust.
The wattage required for any given piece of
equipment is usually printed on the name plate. If only
Estimating Electrical Load
Model Selection
the amp rating is listed, multiply amps x voltage to get
the equipment wattage. If there is no data plate, or if the
information is not supplied on the data plate, call your
dealer for typical wattage requirements of some motors
and appliances. Motors and other loads require several
times full load current under starting conditions. If the
motor starting load is large, a voltage dip may cause the
lights to dim or relays to chatter.
A good rule of thumb is that the continuous load
should be at least 50% of the generator capacity. It may
be advantageous to use two smaller sets.
Circuit Breakers
An AC circuit breaker should be installed on all
Northern Lights generators to protect the generator
Balancing Loads
All loads which will be used at the same time must be
divided up equally among the output legs. For example,
don't put heating loads on one leg and air conditioning
loads on the other leg. Improperly balanced loads may
cause a loss in voltage on the loaded leg and excessive
voltage on the unloaded leg as well as low output. Since
the engine is not affected by an unbalanced overload it is
possible to damage the generator.
Motor Loads
windings in case of a short circuit or an overload due to
unbalanced load conditions.
several voltages (for example, 120 volts or 240 volts) it is
usually more effi cient to wire it at the higher voltage.
Some devices utilizing non-linear loads (SCR
devices) may cause a distortion in the waveform of
the generator's electric output. This can lead to the
malfunction of the voltage regulator and overheating
of the generator rotor. Consult the factory for specifi cs
pertaining to your generator set.
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