Projecta IM120 User Manual page 9

Q. Why does the Inverter turn itself off?
A. If the inverter makes a 'buzz' sound and the "RED" fault light illuminates this indicates that
there is a problem, and the inverter will usually turn off. Most commonly this would be caused
by an appliance that is drawing too much power (overloading), low battery voltage or voltage
drop due to insufficient size cables or poor connections.
Q. The Inverter will not run my appliance even though the appliance draws less
power (Watts) than the size of the inverter?
A. Electrical appliances can be divided into three groups by the way they draw energy (current)
from their power supply. These groups are "Resistive", "Inductive" and "Capacitive" appliances
or also called "loads". Some appliances may draw all three types of power.
• Resistive Loads such as normal incandescent lights (wire filament) always draw a constant
power (watts) from the power supply, that is a 100 Watt light will draw approximately 100 Watts
from the power supply at all times. Resistive loads are the easiest appliances for an inverter
to run.
• Inductive Loads such as a refrigerator (Electric Motor) require a large rush of power (surge
current) to start and then usually draw a more constant power once running. Inductive loads
contain coils of wire (motors, transformers, ballasts, solenoids). When the power is first turned on
these coils of wire draw a large surge current which forms the magnetic flux (magnetic field)
which allows these appliances to work. This magnetic flux is a kind of stored energy.
- The most common inductive appliances are: bar fridges, air compressors, transformers/chargers,
pumps, power tools and fluorescent lights. These appliances can draw 2 - 6 times their normal
running power to start up, that is to run a 80 Watt fridge you may need a 600 or 1000 Watt
inverter.
• Capacitive Loads such as many TV's or many electronic appliances require a large surge
current to start only when they have not been used for a while. This is often due to large
capacitors in the power supply that must be quickly charged when the appliance is turned on.
If the appliance is not used for a few days these capacitors slowly go flat. Resetting the inverter
a couple of times may allow these appliances to work.
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