User Instructions UM1M820BNA
Spec No. 1M820BNA (Model M820B) Issue AH, March 4, 2013
Spec No. 1M820DNA (Model M820D)
Chapter 2. Operation 77
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2.7.6 Programming the ACU+ Power Split Feature
After an ACU+ 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 ACU+.
Procedure
1) Set the Power Split mode to slave. Navigate to Main Menu / Settings / Power System / General /
Contactor Mode. Set this parameter to “Slave Control”.
2) Reboot the ACU+ by pressing ESC and ENT at the same time.
3) Navigate to Main Menu / Settings / Power System / Power Split.
4) Navigate to and set the “Slave Current Limit” to a value that will force the ACU+ system’s rectifiers
to operate in current limiting mode.
Note: The Slave Current Limit must be set lower than the total distribution current from the two
plants. The default value is 60% of the ACU+ power system’s rectifier capacity.
5) Navigate to and set the “Delta Voltage”. This voltage is by default set to 0.5V but can be readjusted.
If the distribution current is lower than 50% of the total capacity of the ACU+ power system, the
“Delta Voltage” can be adjusted to a lower level than 0.5V to get a system voltage that is closer
to the desired float charging voltage.
If the voltage drop between the existing system and the ACU+ system is expected to be >0.5V,
the “Delta Voltage” can be adjusted to a higher level than 0.5 V to get a correct split function.
Temperature controlled battery charging cannot be set in the ACU+ power system in power
split mode. If this function is implemented in the existing power system, a limited function within
a temperature range of approximately ±15°C will be achieved if the Delta Voltage is set to a
higher level, maximum 2.00V.
If the “Delta Voltage” 0.5V is considered to be too high, the split function can be tested at
various modes of operation to find a lower setting.
Optional Function Setup
Equalize Charge Setup
If the equalize charge function is to be used, equalize charge must be implemented in the existing
power system and an equalizing signal from its control unit must be connected to the ACU+.
1) Navigate to Main Menu / Settings / Battery / Charge / EQ Voltage. Set the “EQ Voltage” to the
same value as the equalize voltage of the existing power system.
2) Using the Web Interface (Maintenance / Edit PowerSplit), select the ACU+ digital input
connected to the existing systems equalize control circuit.
Note: Equalize charging is controlled by the existing power system via an incoming digital signal.
The system will remain at the set equalize charge voltage level as long as this signal is
active.
Battery Test Setup
If the battery test function is to be used, battery test must be implemented in the existing power
system and a test signal from its control unit must be connected to the ACU+.
1) Navigate to Main Menu / Settings / Battery / Test.
2) Navigate to and set the “Test End Volt” to the same value as the end voltage of the existing
power system.