Magnum Energy ME-RTR Router - Manual (Page 130)

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2014 Magnum Energy, Inc. Page 122
Appendix D – Using AC Coupling
Appendix D – Using the ME-RTR in an AC Coupled Application
This appendix outlines specifi c settings that need to be adjusted when the router is connected to
Magnum inverters that are 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 effi 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.
An AC coupled system is one where 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) al-
lows the existing battery-less, grid-tie inverter 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 gener-
ated. 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 Magnum inverter into the battery bank.
Since this is not the normal path for the Magnum inverter to sense incoming current, it is not able
to control the battery voltage or regulate the current, providing the possibility that the battery
voltage will rise and be damaged. If the battery voltage is allowed to rise high enough, a High
Battery Voltage fault on the Magnum inverter will occur, causing it to turn off; which in turn shuts
down the entire system (i.e., critical loads and grid-tie inverter turn off). To prevent this from hap-
pening, confi gure the router to work in an AC coupled system to help regulate the battery bank.
D-2 Confi gure the Router to use in an AC Coupled System
The router should be confi gured to work optimally in an AC coupled system, as described below:
1. Enable AC Coupled Support mode to help regulate the battery voltage: Go to the 03C Battery
Type menu (under SETUP: 03 Charger Setup) and select Custom.
Info: AC Coupled Support mode is a control method that causes the inverter output
frequency to increase, causing the grid-tie inverter to cease producing power to avoid
overcharging the system battery. AC Coupled Support mode is available in MS-PAE
Series inverter/chargers (≥Ver 4.1) and is enabled when the battery type is set to
Custom. Once enabled—when the battery voltage increases 2 volts (24-volt units) or 4
volts (48-volt units) above the Absorb Voltage setting—the inverter output frequency
changes to 60.6Hz. The frequency returns to 60.0Hz when the battery voltage falls 2
volts (24-volt units) or 4 volts (48-volt units) below the Absorb Voltage setting, allowing
the grid-tie inverter to reconnect. Note: Because AC Coupled Support mode activates
at a high voltage level, it should only be used as a secondary (i.e., back-up) method to
regulate the battery voltage.
Info:
After selecting Custom under the 03C Battery Type menu, ensure the charge
voltage settings (i.e., Absorb Volts, Float Volts, and EQ Volts)— which display only if
Custom has been selected—are confi gured for your specifi c batteries.
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.
Note: The Aux Relay in the router can also be used to connect and control a DC-controlled relay
to help regulate the battery voltage. See Section 2.9 for information on wiring the Aux Relay, and
CTRL: 04 RTR Aux Relay for information on confi guring the Aux Relay.