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FREQUENTLY ASKED QUESTIONS
Q. What is an inverter?
A. Inverters are designed for powering household appliances from a battery or vehicle. They are
electronic devices that convert (12VDC) battery power to (230/240VAC) mains power.
Inverters are compact and often lightweight making them an ideal source of portable mains
power. Thanks to their portability they are commonly used in cars, caravans, motor homes, boats,
4WD’s and utility vehicles.
Using an inverter with standard household appliances is a much cheaper option than purchasing
specialised 12V appliances for times when power is not available.
There are two different types of inverters, modified sine wave and true sine wave. The difference
between the two is how close the output replicates mains power.
These graphs show the difference in output between mains power, modified sine wave and true
sine wave inverters.
Logically it follows that the process used in a true sine wave inverter is more complex than a
modified sine wave inverter and subsequently they are lot more expensive.
In reality most electric appliances operate unaffected on a modified sine wave and hence they
are more common.
True sine wave inverters are reserved for use on medical equipment and sensitive electrical
appliances.
Inverters are available with different power output levels to suit the type of appliances to be
powered. Small inverters are designed for powering one small low power electrical or electronic
appliance. Larger inverters can be used to power multiple small appliances or one larger
appliance. Typically inverters are not an efficient method for running appliances with very high
power requirements such as electric heaters, stoves, kettles and air conditioners. This is due to
their high current draw and battery consumption.
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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.
