OPERATION
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
Page
63
Example A: If the SEARCH WATTS is set at 32 and a 30-watt incandescent light is turned on, the inverter
will detect the light. The initial load of the bulb is much greater than 32 watts when its filament is cold.
When the light gets bright, the filament heats up and the light becomes a 30-watt load. Since this is below
the setting of 32, the inverter will not detect it and the light will turn off. This can cause cycling of the
inverter between on and off.
Example B: If the SEARCH WATTS setting is 32 and a 40-watt florescent light is turned on, the inverter
will not detect the light. The light presents a smaller load than 32 watts until the gas in the florescent tube
ionizes and begins to glow. This problem is more common with the non-electronic type fluorescent bulbs.
Example C: There are some appliances that draw power even though they are turned off. TVs with instant
on circuits, microwave ovens with digital displays and VCRs with clocks are examples. These loads can
present a dilemma. If the SEARCH WATTS is set higher than the combination of these loads, then an
additional load must be used to bring the inverter out of the search mode before the appliances can be
turned on. If the SEARCH WATTS is set lower than this combination of loads, then the inverter and the
loads will be left on. This will put an additional drain on the batteries (three such 15-watt loads would
amount to an additional 45 amp/hours per 24 hours in a 24 VDC system). One solution is to turn these
items off by using an extension cord with a rocker switch, a switched outlet, or a circuit breaker for the
circuit. Unfortunately, this solution does not allow a clock to retain its setting and may cause it to blink
constantly while operating.
SETTING SEARCH MODE SPACING
The SET SEARCH SPACING menu item is calibrated in cycles. To test for loads once each second,
adjust this setting to 59 (for 60 Hz models); to test for loads about twice a second, adjust the setting to 30.
NOTE: The lower the search spacing value – the less time it takes for the inverter to bring up a load. The
lower the setting), the greater the power consumption while in the search mode, thus reducing power. The
factory default value (59) is acceptable for most applications. The range is from 4 to 255.
LOW BATTERY PROTECTION
When the actual battery voltage reaches the LOW BATTERY CUT OUT menu item setting for the LBCO
DELAY period, the inverter shuts off to prevent the battery from being over-discharged. If the inverter is
setup to automatically start a backup generator (Gen Auto Start Menu), then it will start once the battery
reaches the LBCO setting for the selected time (30 seconds, etc).
Any of the following three conditions will return the inverter to normal operation, after a LBCO condition:
1. Power is applied to the AC HOT IN 1 or AC HOT IN 2 input terminals, allowing the inverter to operate
as a battery charger.
2. The inverter is manually restarted by pushing the red ON/OFF button and selecting OFF and then
SRCH or ON.
3. Battery voltage rises above the SET LOW BATTERY CUT IN menu item setting.
While the inverter is shut off due to the battery reaching the LOW BATTERY CUT OUT settings, the red
ERROR LED will be illuminated. When the battery voltage increases to the LOW BATTERY CUT IN
setting, the inverter will automatically turn back on and the ERROR LED will turn off.
ADJUSTING THE LOW BATTERY PROTECTION
There are three settings used to prevent over-discharge of the battery. These settings are located under
the INVERTER SETUP (9) menu heading. See the SETUP MENU section for instructions on accessing
these settings.
The SET LOW BATTERY CUT OUT menu item determines the voltage level that the battery must reach for
it to be considered low. The inverter will continue to operate until the voltage has continuously remained
below this setting for the time period from the SET LBCO DELAY menu item. Once the inverter has shut off,
the battery voltage must rise above the value from the SET LOW BATTERY CUT IN menu item.
The default LOW BATTERY CUT OUT setting may be lower than what is often recommended for many
applications by battery manufacturers. It is set to allow maximum performance from the inverter, not to
maximize the life of the battery. If the system is properly designed, the inverter should not reach the LBCO
setting very often. If the system is expected to utilize the LBCO control on a regular basis, then increasing
this setting is recommended.
Summary of Contents for SW II - REV 4.01
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