©
2010 Magnum Energy, Inc
Page 35
Operation
3.2 Standby
Mode
The RD Series features an automatic transfer relay and an internal battery charger when operating
in Standby Mode. Standby Mode begins whenever AC power (utility power or generator) is connected
to the inverter’s AC input. Once the AC voltage and frequency of the incoming AC power is within
the AC input limits, an automatic AC transfer relay is activated. This transfer relay passes the
incoming AC power through the inverter to power the AC loads on the inverter’s output. This
incoming power is also used to activate a powerful internal battery charger to keep the battery
bank charged in case of a power failure. Refer to Figure 3-2 to see the
fl
ow of power from the AC
input to the DC and AC output while in Standby Mode.
240
V A C
120
V A C
120
V A C
A C
O U T
A C H ot
T rans fer R elay
A C H O T 1 IN
A C H O T 2 IN
C B3 (3 0 A )
A C N E U T R A L IN
A C G R O U N D
P ow er T rans form er
F E T B ridge
A C
D C
D C
O U T
A C H O T 1 O U T
A C H O T 2 O U T
C B2
(optional )
C B1
(optional )
D C P O S IT IV E
D C N E G A T IV E
A C N E U T R A L O U T
240
V A C
120
V A C
120
V A C
A C
IN
C onnects to chassis of inverter
Figure 3-2, Power Flow - Standby Mode
3.3 Battery
Charging
Magnum Energy’s RD Series is equipped with an active PFC (Power Factor Corrected) and PI
(Proportional-Integral) multi-stage battery charger. The PFC feature is used to control the amount
of power used to charge the batteries in order to obtain a power factor as close as possible to 1
(or unity). This causes the battery charger to look like a resistor to the line (forces the charge
current waveshape to mirror the voltage waveshape). The PI feature allows the charger voltage
and current to change independently. These two features maximize the real power available from
either utility power or generator AC power sources, which translates into less power wasted and
greater charging capabilities than most chargers available today.
When an AC source is connected to the AC input, the inverter begins monitoring for acceptable AC
voltage. Once the inverter has accepted this AC voltage, the AC transfer relay closes and the Charge
Mode begins. After Charge Mode begins, the DC voltage is monitored to determine the charging
stage. If the DC voltage is low (
≤
12.8 VDC/12 volt models or
≤
25.6 VDC/24-volt models), the
charger begins Bulk Charging. If the DC voltage is high (> 12.8 VDC/12 volt models or >25.6 VDC/
24-volt), the charger will skip the Bulk and Absorb Charging stages and go directly to Float Charging.
The multi-stage charger can use up to
fi
ve different charging stages to help monitor and keep the
batteries properly maintained. The
fi
ve stages include an automatic 4-stage charging process:
Bulk, Absorb, Float, and Full Charge; and a manual Equalization (EQ) Charge stage. The automatic
4-stage charge process provides complete recharging and monitoring of the batteries without
damage due to overcharging. The EQ stage (requires the ME-RC50 remote to enable equalization
charge) is used to stir up strati
fi
ed electrolyte and to try to reverse battery plate sulfation that
may have occurred.
While charging, the unit may go into Charger Back-off protection, which automatically reduces
the charge current to the batteries. This is caused by: 1) the internal temperature is too hot – the
charger automatically reduces the charge rate to maintain temperature; or, 2) the AC input voltage
falls below 90 VAC – the charger will stop charging to help stabilize the incoming AC voltage.
