Magnum Energy MS Series - Manual (Page 54)

©
2012 Magnum Energy, Inc. Page 45
Operation
3.2 Standby Mode
Magnum Energy’s MS Series features an internal battery charger and an automatic transfer
relay when operating in Standby mode. The Standby mode begins whenever AC power (utility
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
VAC
120
VAC
120
VAC
AC
OUT
Neutral-Ground
Transfer Relay
AC Hot
Transfer Relay
AC HOT 1 IN
AC HOT 2 IN
CB3 (30A)
AC NEUTRAL IN
AC GROUND
Power Transformer
FET Bridge
AC
DC
DC
OUT
AC HOT 1 OUT
AC HOT 2 OUT
CB2
(optional)
CB1
(optional)
DC POSITIVE
DC NEGATIVE
AC NEUTRAL OUT
240
VAC
120
VAC
120
VAC
AC
IN
Figure 3-2, Power Flow - Standby Mode
3.3 Battery Charging
The MS Series is equipped with a PFC (Power Factor Corrected) and PI (Proportional-Integral) multi-
stage battery charger. The PFC feature controls the amount of power used to charge the batteries
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 wave shape to mirror the voltage wave
shape). The PI feature allows the charger voltage and current to change independently. These two
features maximize the real power available from the AC power source (i.e., utility or generator),
which translates into less power wasted and greater charging capabilities than most chargers today.
When an AC source is connected to the AC input, the inverter begins monitoring for acceptable AC
voltage. Once the AC voltage is accepted, the AC transfer relay closes the charge mode begins.
After the charge mode begins, the inverter’s battery voltage is monitored to determine the charging
stage. If the battery 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 models), the charger will skip the Bulk and Absorb charge stages and go directly to Float
charging. However, if the incoming AC power is lost and returns within 2 minutes the charge mode
returns to the charge stage it was in prior to losing AC input—regardless of the battery voltage.
The multi-stage charger in the MS Series can use up to fi ve different charging stages to help monitor
and keep the batteries healthy. The fi ve stages include an automatic 4-stage charging process (see
Figure 3-3): 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 a remote display to enable) is used
to stir up stratifi ed electrolyte and to reverse any 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.