NetSure
™
Control Unit (NCU)
User Manual, UM1M830BNA
Spec. No: 1M830BNA, 1M830DNA Code: UM1M830BNA
Model No: M830B, M830D Revision M, May 12, 2017
Preparing the Existing and NCU Power Systems
Install and turn-up the NCU power system as describe in
the installation instructions furnished with the power
system.
Set the float voltage on both the existing and NCU power
systems to the same level. Temperature compensation
functionality, if used, should be disabled on both power
systems.
Paralleling the Systems
Connect the Battery and Battery Return busbars of the
NCU Power System to the main charge busbars (rectifier
side of the shunt) on the parallel power system. Size the
cable for the largest current between systems.
Note 1: The connections between the two power systems
should be done with power cables appropriately
sized to be capable of carrying the maximum
current that can circulate between the two power
systems.
Note 2: If the parallel power system incorporates a main
plant shunt, the connections of the cables from
the NCU power system to the parallel power
system shall be made on the main charge busbars
(rectifier side of the shunt).
Note 3: To compensate for voltage drop, it is
recommended to connect the NCU power system’s
remote sense leads (if available) to the same point
of sensing as the parallel power system.
Note 4: There shall be only one battery return reference
(BRR) cable for the two power systems. If the cable
is appropriately sized on the parallel power
system, keep it as the BRR for both power systems.
If the cable is not appropriately sized on the
parallel power system, install a new BRR cable and
connect it preferably to the NCU power system
since the parallel power system may eventually be
phased out.
Note 5: If battery disconnect units (BDUs) are used on the
new or parallel power system, these shall be wired
in such a way as to be all triggered simultaneously
in order to prevent any overloading of these.
Note 6: For the size and number of bridge cables between
the two power systems, take into consideration
the voltage drop, the available connecting points
in each system, as well as the fact that these
cables are unfused and shall therefore be run on a
dedicated cable rack. “C” or “H” taps may be used
to make full use of available connecting points.
Note 7: The legacy system retains the function of its
controller and the percent of load on each plant is
controlled by the NCU. Alarms may be sent
individually from each plant, or combined using an
NCU Interface Board and the programmable relays
resident in the controller.
Note 8: Add a label on both power systems to indicate that
these are operating in the Power Split Mode with
each other.
Optional Function Connections: The following signals
from the existing system must be connected to digital
inputs of the NCU system interface board for these
functions to be active: Equalize Charge in Progress,
Battery Test in Progress, Load LVD Active, and Battery
LVD Active. Otherwise disable these functions.
Programming the NCU Power Split Feature
After an NCU power system has been connected to an existing
power system and both systems set for the same float voltage, you
will have to configure the Power Split parameters in the NCU.
Procedure
1. In the Web Interface menus, set the Power Split mode to
enabled. Navigate to Settings Menu / System / Power
System / PowerSplit Mode. Set this parameter to
“enabled”.
2. Reboot the NCU by pressing ESC and ENT at the same
time.
3. Navigate to Settings Menu / System / Power System.
4. Set the “Power Split Current Limit Value” to a value that
will force the NCU system’s rectifiers to operate in
current limiting mode.
NOTE: The Power Split Current Limit Value must be set lower
than the total distribution current from the two plants. The
default value is 60% of the NCU power system’s rectifier
capacity.
5. Set the “Delta Voltage”. This voltage is by default set to
0.5 V but can be readjusted.
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