Trace Engineering LEGEND II Manual page 66

Trace Engineering inverters can drive nearly every type of load. However, there are special situations
in which inverters may behave differently than public power. Trace has provided the following
knowledge as guidelines only. Trace does not guarantee that your experiences with any particular
product will duplicate ours whether good or bad. Manufacturers change the topologies of circuits
routinely, in an effort to save money and at the same time improve a product. This means that a
product we list as working or not working with a modified square wave inverter may react conversely
to our findings in your situation. Trace assumes no responsibility for failure of a particular product in
your application! It is up to you to decide to and to test a given product with your specific system. We
do not endorse any product in particular.
Very small loads - If the power consumed by a device is less than the threshold of the search mode
circuitry, it will not run. See the section Search Sense for ways to solve this problem. Most likely the
solution will be to defeat the search mode feature.
Fluorescent lights & power supplies - Some devices when scanned by search sense circuitry
cannot be detected. Small fluorescent lights are the most common example. (Try altering the plug
polarity by turning the plug over). Some computers and sophisticated electronics have power
supplies that do not present a load until line voltage is available. When this occurs, each unit waits
for the other to begin. To drive these loads either a small companion load must be used to bring the
inverter out of its search mode, or the inverter may be programmed to remain at full output voltage by
defeating the search mode feature. See the section Search Sense .
Microwave ovens- Microwave ovens are sensitive to peak output voltage. The higher the voltage,
the faster they cook. Inverter peak output voltage is dependent on battery voltage and load size.
The high power demanded by a full sized microwave drops the peak voltage several volts due to
internal losses. Therefore, the time needed to cook food will be increased if battery voltage is low.
Some microwave ovens may not operate at all. Try it before you buy it.
Clocks- The inverter's crystal controlled oscillator keeps the frequency accurate to within a few
seconds a day. However, external loads in the system may alter the inverter's output waveform
causing clocks to run at different speeds. This may result in periods during which clocks keep time
and then mysteriously do not. Most clocks do not draw enough power to trigger the load sensing
circuit. In order to operate without other loads present, the load sensing will have to be defeated
(See section on Search Sense ). Clock accuracy is also affected by the accuracy of the generator.
The best solution is to buy a battery-operated clock, or a clock that is not dependent on line
frequency or voltage. Any clock with a crystal controlled oscillator will probably work just fine.
Searching- If the amount of power a load draws decreases after it turns on, and if this "on" load is
less than the load sensing threshold, it will be turned alternately on and off by the inverter.
Incandescent light bulbs may present this problem when the search threshold is set near the wattage
rating of the bulb.
WK