OPERATION
Page
62
Copyright
Trace Engineering Company, Inc.
5916 - 195th Street N. E.
Arlington, WA 98223
Telephone: 360/435-8826
Fax: 360/435-2229
www.traceengineering.com
SW Series Inverter/Charger
Part No. 2031-5
Rev. B: Sept 1, 1999
INVERTER MODE
IN BRIEF
The inverter makes a stepped approximation to a sine wave. The number of steps typically varies from 34
to 52 per cycle. Lower battery voltage and/or higher output power level increases the number of steps.
Higher battery voltage decreases the number of steps. Distortion varies from 3% to 5%. The inverter is
able to control the AC output voltage, allowing the inverter to also sell power into a utility grid or assist
during the operation of heavy loads by operating in parallel with another AC power source such as a
engine powered generator.
SEARCH MODE CONTROL
An automatic search mode circuit is available to minimize the power draw of the inverter when no loads
are being operated. This reduces the power consumption from 16 watts with no load to less than 1 watt
(when using the default settings). To do this, the output is reduced to pulses of a single AC cycle with an
adjustable delay between pulses. These pulses are used to detect the presence of a load. When a load is
detected, the inverter’s output goes to full 120 VAC output. The sensitivity of the detection circuit and the
spacing of the pulses are user adjustable using the Control Panel.
This feature can save a considerable amount of power, particularly in smaller systems that do not have
loads operating all of the time. In larger systems, this feature may not result in as much savings. If
continuous operation of an AC load is required (such as when powering a microwave clock, VCR timer,
computer, or fax machine), then using the search mode is not recommended.
To enable the search mode: Select SRCH mode from the SET INVERTER menu item, accessible by
pushing the red ON/OFF MENU button. Pressing the red ON/OFF MENU button can also access the
SRCH mode. It is also located as the first menu item under the INVERTER MODE (1) menu heading.
Pressing the red ON/OFF MENU button again will move the cursor one position to the right. The SET
POINT buttons can also be used to move the cursor right or left. To disable the search mode, select ON
from the SET INVERTER menu item.
Successful operation of the system utilizing the search mode requires some initial tuning of the search
mode settings to match the loads connected in the system. If the loads change significantly, re-tuning of
the settings may be required. The benefit of the search mode circuit only is realized if the inverter is able
to enter the energy saving search mode for substantial periods of the day. Occasional checking of the
yellow INVERT LED operation should be done to ensure that the search mode is being used when all of
the loads are turned off (it should blink slowly if it is searching for a load).
SETTING SEARCH MODE WATTS
The search mode is user adjustable to allow fine-tuning of its operation. The settings are located under
the INVERTER SETUP (9) menu heading in the SETUP MENU. The following example explains the
operation:
Example: With the SEARCH WATTS setting at 32, a 50-watt load will bring the inverter to full output
voltage. However, a 30-watt load will leave the inverter in its energy saving search mode. If the sensitivity
is increased by lowering the setting to 16, a 20-watt load will bring the inverter out of the search mode,
while a 5-watt load will not.
When in the search mode, the yellow INVERT LED will blink slowly and the inverter will make a ticking
sound. At full output voltage, the yellow INVERT LED will stay on and the inverter will make a steady
humming sound. When the inverter is used as an uninterruptable power supply, the search mode should
be defeated.
Exceptions: (Murphy's Law) Unfortunately, things don’t always work the way the manual says.
BATTERY
INVERTER
AC LOADS
DC
AC
Summary of Contents for SW II - REV 4.01
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