Trace Engineering SW II - REV 4.01 Owner'S Manual Download

Page: 77 / 152

OPERATION



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

INVERTER/CHARGER MODE

IN BRIEF

The SW Series Inverter/Charger is capable of automatically transferring AC loads from the inverter to a
utility grid or generator. Once transferred, the inverter can recharge the battery. The inverter/charger can
transfer upon the availability of AC power (FLT mode), either at a specific time each day (using the GRID
USAGE TIMER (18) menu heading), or upon a low battery condition (LBX mode).

TRANSFERRING UPON AVAILABILITY OF AC POWER

When AC power is supplied to the AC HOT IN 1 or AC HOT IN 2 input, the inverter automatically transfers
from inverter mode to battery charger mode. Before transferring, the inverter verifies that both the AC
input voltage and frequency are within tolerance. It then synchronizes waveforms and connects to the
inverter’s AC output without interruption of power.

The FLT mode is the default mode (see the GRID USAGE menu item under the INVERTER SETUP (9)
menu heading) and may be used with AC power supplied to either the AC HOT IN 1 or AC HOT IN 2
input. This is the proper mode for most utility connected applications or for use with a back-up generator
that is being manually or automatically started.

The SLT mode is used only with AC power supplied to the AC HOT IN 1 input. The SLT mode is selected
from the GRID USAGE menu item under the INVERTER SETUP (9) menu heading. In this mode, the only
operational difference is that the battery charger will only be engaged for a single period of time each day,
set by the BULK CHARGE TRIGGER TIMER (15) menu heading setting. This reduces the power
consumption of the inverter over the period of a day. It is also used in applications where the slight noise
of the inverter might be undesirable, such as at night. AC power continues to be passed through the
inverter’s transfer relay while the charger is not engaged. If the AC source fails, the inverter will turn on
automatically and power the connected AC loads. When utility power returns, the AC loads will be
reconnected to the utility and the battery charger will complete a bulk charge cycle. Once this has been
completed the battery charger will turn off, but the loads will remain connected to the utility.

TRANSFERRING BASED ON BATTERY VOLTAGE

The LBX mode is used only with AC power supplied to the AC HOT IN 1 input. The LBX mode is selected
from the GRID USAGE menu item under the INVERTER SETUP (9) menu heading. In this mode, the
decision to transfer to and from charger mode will be based upon the battery voltage. With LBX enabled,
the SET LOW BATTERY CUT IN VDC setting and the SET LOW BATTERY TRANSFER VDC setting
determine the DC transfer voltages. When the battery voltage reaches the LOW BATTERY TRANSFER
VDC setting for more then 20 seconds, the AC loads are transferred from the inverter to the utility. If the
battery voltage reaches the LOW BATTERY CUT IN VDC setting, the AC loads are transferred from the
utility to the inverter. The low battery transfer system includes a 20 second delay so that large loads are
less likely to cause a transfer to the utility grid during motor startup, etc.