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21January2021/Version 0
LEM International SA
Chemin des Aulx 8
1228 PLAN-LES-OUATES Switzerland
www.lem.com
5.3. Energy registering
Conventional direction for current measurement fills the "import" energy register. This flow refers
to I1 and I2 indications on Sensor Unit marking (see below figure), and depends on product
reference: see "Table 4: Counting direction references".
A current flow the other way around fills the export energy register.
COM
VP
VN
I1
I2
DCBM SU 4000
I1 I2
1202340856
4-80(400) A DC
150V...1000V
CI.B EN50470
-40°C / +85°C IP10
Ue: 1000V DC Ie: 400A DC Uimp: 8kV
If this seal is removed
or broken LEM does
not guarantee the
product and data
integrity
VP and VN shall be connected to the positive and negative bus bars respectively. Voltage inversion
does not cause any damage to the DCBM but raises a status to indicate the wiring error (status
reversedVoltage
The following graph shows how directions of current flow and voltage difference are registered by
the DCBM.
Figure 23: Counting quadrants for the DCBM
Anti-creep is performed on current and voltage measurements, as visible of above graph. Hence,
no energy is accumulated in any of the following conditions:
• If voltage is below datasheet value "Minimum limit range of operation
U
min
"
• If current is between
I
st
and
-I
st
("Starting current" as in datasheet)
Import energy
Export energy
Current
Voltage
I
st
I
max
U
min
U
max
-I
st
-I
max