Eltek Smartpack - Battery Symmetry Measurements

6 Functionality Description
User’s Guide Smartpack Monitoring & Ctrl Unit,
350003.013, v5-2006-11 27
Battery Symmetry Measurements ⎯ 48V Systems
Symmetry measurement is a battery monitoring method for automatically detecting
unbalanced battery blocks.
For information about 24V systems symmetry measurements, read the “Quick Start
Guide Flatpack2 PS System” Art. 356804.103.
Symmetry monitoring of a 48V battery string may be
performed after three different methods:
o Block measurement method
Measuring each battery block
o Mid-point measurement method
Measuring from the mid-point of the battery
string to one end
o Double mid-point measurement method
Measuring from the mid-point of the string to
both ends
The mid-point measurement method requires 2
symmetry wires per battery string; the double mid-
point measurement method requires 3 symmetry wires
per battery string, while the block measurement
method requires 5 symmetry wires per battery string.
Refer to the system’s quick start guide for connections.
Cabinetized DC power systems are normally delivered
with the symmetry measurement method and the
number of measurement points already
preprogrammed in the Smartpack controller. Any
deviation from factory settings requires Symmetry
reconfiguration via the PowerSuite PC program.
Each Smartpack controller is equipped with 8 battery
symmetry inputs (on CON4 and CON3), enabling
symmetry measurement of:
o 2 battery strings (block meas. method)
o 4 battery strings (double mid-point meas. method)
o 8 battery strings (mid-point meas. method)
Figure 21 Example of terminal connection points for Symmetry Block, Mid-point and
Double Mid-point measurement methods in 48V systems
Battery Symmetry
Block Measurement
Four measurement points per string
(Serial measurement)
Card, Art. 200576
Serial Switches
Set all 4 switches
ON (down)
Symmetry
1 2 3 4
+ (0V)
— (-48V)
-
+
+ + +
Battery Symmetry
Mid-point Measurement
One measurement point per string
Symmetry 1
+
-
+ (0V)
— (-48V)
Card, Art. 200576
Serial Switches
Set all 4 switches
OFF (up)
Battery Symmetry
Double Mid-point Measurement
Symmetry
2
+
+ (0V)
— (-48V)
Symmetry
1
+
-
Card, Art. 200576
Serial Switches
Set all 4 switches
ON (down)
Two measurement points per st
r
ing,
from the middle to the outer terminals