©
2020 Sensata Technologies
Page 33
Operation
3.2 Standby
Mode
The MSH3012RV features an automatic transfer relay and an internal battery charger when operating
in Standby mode. The Standby mode begins whenever AC power (shore power or generator) is
connected to the inverter’s AC input. Refer to the
fi
gures below to see the
fl
ow of power from the
AC input to the DC and AC outputs while in Standby mode.
When a 120VAC only source is connected to the AC HOT 1 IN terminal (i.e., Single In), this AC
source passes-thru to both the AC HOT 1 OUT and AC HOT 2 OUT terminals as shown in Figure 3-2.
Figure 3-2, Power Flow – Standby Mode (Single In)
AC Hot 2
Transfer Relay
120
VAC
120
VAC
AC
OUT
Neutral-Ground
Transfer Relay
AC Hot 1
Transfer Relay
AC GROUND
Power Transformer
FET Bridge
AC
DC
DC
OUT
AC HOT 1
OUT
DC POSITIVE
DC NEGATIVE
AC NEUTRAL
OUT
AC
IN
AC NEUTRAL IN
AC HOT 1 IN
AC HOT 2 IN
CB1
(50A)
CB2
(50A)
120
VAC
AC HOT 2 OUT
AC GROUND
AC
Output
Relay
0
VAC
AC Hot 2
Transfer Relay
120
VAC
120
VAC
AC
OUT
Neutral-Ground
Transfer Relay
AC Hot 1
Transfer Relay
AC GROUND
Power Transformer
FET Bridge
AC
DC
DC
OUT
AC HOT 1
OUT
DC POSITIVE
DC NEGATIVE
AC NEUTRAL
OUT
120
VAC
AC
IN
AC NEUTRAL IN
AC HOT 1 IN
AC HOT 2 IN
CB1
(50A)
CB2
(50A)
240VAC
or
208VAC
120
VAC
AC HOT 2 OUT
AC GROUND
AC
Output
Relay
240VAC
or
208VAC
Figure 3-3, Power Flow – Standby Mode (Dual In)
As shown in Figure 3-3, when a 120/240VAC split-phase (or 120/208VAC three-phase) source is
connected to the AC HOT 1 IN and AC HOT 2 IN terminals (i.e., Dual In), each input will pass-thru
to its respective output. There is a delay connecting to the two inputs; this delay is designed to
allow better transfer behavior.
