Owner`s manual

VANNER Incorporated Owner’s Manual
SRC12-1200L/S INVERTER/CHARGER
10/15/10 - 11:33 AM
20
Figure 1 Battery Charging Graph
10.2 AUTOMATIC POWER TRANSFER SWITCH THEORY OF OPERATION
The function of the Automatic Transfer Switch is to automatically accept AC input power from shore or
generator, and use this power to operate inverter loads and to provide power for battery charging. Upon loss
of AC input power, the transfer switch automatically switches the AC loads back to inverter power. Transfer
time is approximately 30 milliseconds (0.030 seconds). The 0.030 second transfer time allows all but the
most sensitive loads to transfer from inverter power to shore power and back to inverter power without
interruption.
AC input voltage is monitored for proper tolerance at all times. When the AC input is within tolerance for
approximately 5 seconds, the power is passed through to the output circuit and the SRC12-1200L/S
automatically switches from inverter mode to battery charger mode. The unit automatically switches back to
inverter mode when input power is disconnected or when input power is no longer within tolerance. See
specifications page for AC input voltage tolerances. The 5 second delay occurs only if the inverter is fully
ON when input power becomes available. There is no 5 second time delay if the inverter is in the „Load
Demand Mode‟ when input power becomes available.
The factor that determines whether the unit is in „inverter mode‟ or „battery charger mode‟ is the presence or
absence of „in-tolerance‟ input power. Whenever „in-tolerance‟ input power becomes available the unit
automatically switches from inverter mode to charger mode.
The transfer switch switches both AC hot and AC neutral. For safety purposes the inverter output neutral is
connected to the inverter chassis ground only when the unit is in inverter mode. This is a requirement of the
National Electric Code for all systems of this type that neutral should be connected to ground only at the
source of AC power, which is the inverter when in inverter mode. When an external AC input (shore power,