Xantrex RV2012 Manuel d'utilisateur télécharger pdf (Page 35)

Xantrex RV Series Inverter/Charger Owner’s Manual

Applications

Resistive Loads

These are the loads that the inverter finds the simplest and most efficient to drive. Voltage and

current are in phase, or, in this case, in step with one another. Resistive loads usually generate

heat in order to accomplish their tasks. Toasters, coffee pots and incandescent lights are typical

resistive loads. Larger resistive loads—such as electric stoves and water heaters—are usually

impractical to run off an inverter. Even if the inverter could accommodate the load, the size of

battery bank required would be impractical.

Inductive Loads

Any device that has a coil of wire in it probably has an inductive load characteristic. Most

electronics have transformers (TVs and stereos, for example) and are therefore inductive.

Typically, the most inductive loads are motors. The most difficult load for the inverter to drive will

be the largest motor you manage to start. With inductive loads, the rise in voltage applied to the

load is not accompanied by a simultaneous rise in current. The current is delayed. The length of

the delay is a measure of inductance. The current makes up for its slow start by continuing to flow

after the inverter stops delivering a voltage signal. How the inverter handles current that is

delivered to it while it is essentially “turned off” affects its efficiency and “friendliness” with

inductive loads. The best place for this out-of-phase current is in the load, and the RV Series

Inverter/charger’s “impulse phase correction” circuitry routes it there.

Inductive loads, by their nature, require more current to operate than a resistive load of the same

wattage rating, regardless of whether power is being supplied by an inverter, a generator or grid.

Induction motors (motors without brushes) require two to six times their running current on

startup. The most demanding are those that start under load, such as compressors and pumps.

Of the capacitor start motors, typical in drill presses and band saws, the largest you may expect to

run is ½ to 1 hp. Universal motors are generally easier to start. Since motor characteristics vary,

only testing will determine if a specific load can be started and how long it can be run.

If a motor fails to start within a few seconds, or it begins to lose power after running for a time, it

should be turned off. When the inverter attempts to start a load that is greater than it can handle, it

will turn itself off after about 10 seconds.

Problem Loads

Xantrex inverters can drive nearly every type of load. However, there are special situations in

which inverters may behave differently than public power.

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 “Search Sense Mode Using Optional RC7 Remote“ on page 5

for ways to solve this problem.

Fluorescent lights & power supplies: Some devices when scanned by the load sensor cannot

be detected. Small fluorescent lights are the most common example. (Try altering the plug

polarity—turn 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. See the sections on Search Sense Mode on pages 5 and 20.

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 will drop the peak voltage several

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Xantrex RV2012 Manuel d'utilisateur Page 35

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