Schneider Electric User Guide

Inverter Applications
975-0240-01-01 4–3
Inverter Applications
The Conext XW+ performs differently depending on the AC loads connected to it.
If you are having problems with any of your loads, read this section.
Resistive Loads
Resistive loads are the easiest and most efficient to drive. Voltage and current
are in phase, which means they are in step with one another. Resistive loads
generate heat in order to accomplish their tasks. Toasters, coffee pots, and
incandescent lights are typical resistive loads. It is usually impractical to run
larger resistive loads—such as electric stoves and water heaters—from an
inverter due to their high current requirements. Even though the inverter may be
able to accommodate the load, the size of battery bank will limit inverter run time.
Motor Loads
Induction motors (AC motors without brushes) require up to six times their
running current on startup. The most demanding are those that start under load
(for example, compressors and pumps). Of the capacitor start motors (typical in
tools such as drill presses and band saws), the largest you can expect to run is
1 horsepower. Universal motors are generally easier to start. Check that the
Locked Rotor Amps (LRA) rating of the motor load does not exceed the
maximum surge current rating of the inverter. Since motor characteristics vary,
only testing will determine whether a specific load can be started and how long it
can be run.
If a motor fails to start within a few seconds or loses 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, the inverter may shut down from an AC overload fault.
Problem Loads
Very Small Loads
If the power consumed by a device is less than the threshold of the search mode
circuitry, and search mode is enabled, the inverter will not run. Most likely the
solution will be to disable Search mode or lower the sense threshold. (See “Using
Search Mode” on page 3–9.)
Fluorescent Lights and Power Supplies
Some devices cannot be detected when scanned by search mode circuitry.
Small fluorescent lights are the most common example. 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 like a light bulb rated for
more than the Search Watts setting must be used to bring the inverter out of
search mode, or the inverter may be programmed to remain on by disabling
search mode (See “Using Search Mode” on page 3–9).
Conext XW+ Owner's Guide NA (975-0240-01-01).book Page 3 Monday, November 27, 2017 10:00 AM