© 2017 Sensata Technologies
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Appendix D – Using AC Coupling
Appendix D – Using the ME-ARTR in an AC Coupled Application
This appendix provides information when the router is used in an AC coupled system.
D-1 What is an AC Coupled System
Many homeowners utilize renewable energy (e.g., PV, wind, etc.,) by installing high ef
fi
ciency,
battery-less, grid-tie inverter systems to offset their power consumption from the utility grid.
However, during a utility power outage, the grid-tie inverter is required to shut down. This can
cause considerable frustration as the homeowner realizes that the critical loads in the home (e.g.,
refrigerator, lights, water pump, etc.,) are no longer powered, and all the energy produced by the
renewable energy source is being wasted while the utility power is out.
In an AC coupled system, all the energy sources and loads are connected directly to the AC side.
Installing a bi-directional battery-based inverter (such as Magnum’s MS-PAE Series) allows the
existing battery-less, grid-tie inverter to continue to operate; and therefore, to continue to utilize
the renewable energy to power the home’s critical loads during a power outage—all from the
AC side. However, in an AC coupled system, during a utility power interruption, the main panel
loads are no longer connected and the utility grid is not available to export any excess power that
is generated. This means there may be more power on the AC side than the critical loads can
consume, causing current to be pushed back thru the output of the MS-PAE Series inverter into the
battery bank. Since this is not the normal path to sense incoming current, this inverter is not able
to control the current and regulate the battery voltage, providing the possibility that the battery
voltage will rise enough to be damaged. To prevent this from happening, the MS-PAE Series
inverter includes a “Frequency Shift” feature that can be used to regulate the battery voltage.
D-2 Frequency Shift Feature
The frequency shift feature—when enabled
1
—causes the output frequency of the MS-PAE Series
inverter (
≥
Version 6.0) to change based on the inverter’s battery voltage. As the battery voltage
begins rising, the output frequency starts decreasing; as the battery voltage returns to its correct
voltage level, the frequency increases.
The MS-PAE Series inverter is optimized to work with Magnum Energy’s MicroGT500 grid-tie inverter
to regulate battery voltage. During a utility power interruption, if the battery voltage begins to rise
above the absorb voltage, the output frequency of the MS-PAE Series will start shifting down. The
MicroGT500 responds by decreasing its output current to avoid overcharging the battery. As the
battery voltage falls, the MS-PAE Series frequency starts shifting back up - allowing the MicroGT500
to gradually provide more current so that the battery can return to its absorb voltage level. The
response time on when the frequency continues to shift down or start shifting back up depends on
how fast the battery voltage rises or returns to the absorb voltage level.
Note 1:
The Frequency Shift feature is enabled when the battery type is set to Custom, and
activates when the battery voltage increases above the absorb voltage setting.
D-3 Con
fi
gure the Router to use in an AC Coupled System
The router should be con
fi
gured to work in an AC coupled system, as described below:
1. Enable the Frequency Shift feature: Select
Custom
under the
03C Battery Type
menu (under
SETUP: 03 Charger Setup
), and then set the
Absorb Volts
,
Float Volts
, and
EQ Volts
per your
battery manufacturer’s speci
fi
cations.
Info:
In an AC Coupled system without grid (i.e., Micro Grid), ensure the MS-PAE Series
inverter is >Version 6.1 and set the
03D Absorb Done Time menu
(under
SETUP: 03
Charger Setup
) which allows the voltage to transition from the absorb voltage level to
the
fl
oat voltage level—to ensure the batteries are not overcharged.
2. Turn off the Search mode feature: Go to the
02A Search Watts Sensitivity
menu (under
SETUP: 01 Inverter Setup
) and set it to
OFF
.
3. Turn off Parallel Threshold: Go to the
02G Inverter Threshold to Start Parallel
menu (under
SETUP: 01 Inverter Setup
) and set it to
OFF
.
4. Ensure the inverter is set to automatically accept grid power when available: Go to the
01 AC
In Control
menu (under
CTRL: 01 AC In Control
) and set to
Auto Connect
.
Содержание ME-ARTR
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