Siemens SICAM - Primary Current Settings

i
i
NOTE
If the CrossBlockTimer value is set as 0, then the fault indication is not blocked in case of an inrush-current
detection.
Primary Current Settings
Based on the selected current-transformer type, the rated primary current parameter can be set from 50 A to
1000 A via the user interface or Modbus registers.
After setting the parameters, connect the current inputs I
1
, I
2
/I
N
, I
3
via low-power current transformers (LoPo
CTs) or conventional current transformers (CT). For interfacing via conventional CTs, use a 1 A CT adaptor
(MLFB 6MD2320-0AA10-1AA0) or a 5 A CT adaptor (MLFB 6MD2320-0AA20-1AA0).
The LoPo CTs convert the primary current to a proportional output voltage. The device has a rated primary
current setting of 300 A (@ 225 mV).
Ground-Current Calculation
For solidly-grounded systems, the ground currents are calculated from the vector sum of 3 phases. The ground
current is also calculated for isolated/resonant-grounded systems, when the phase-current sensor for phase L2
is connected to the I
2
/I
N
terminal.
If the ground-current sensor is connected to the I
2
/I
N
terminal, the ground current can be measured for
isolated/resonant-grounded systems.
When the ground current is measured, the ground current can be configured from 25 A to 150 A.
For more information about the ground sensor, refer to Ground Sensor, Page 123.
The calculation/measurement of the ground current is determined by setting the Ground-current acquisition
parameter.
i
i
NOTE
When the cos φ/sin φ functionality is used in isolated or resonant-grounded systems, the deviation of the
ground current (I
dir
) calculated is within 3 A.
i
i
NOTE
For isolated systems, if the angle difference between V
NG
and I
N
is closer to 0°, the deviation of the calcu-
lated ground current (I
dir
) can be more than 3 A.
i
i
NOTE
For resonant-grounded systems, if the angle difference between V
NG
and I
N
is closer to 90°, the deviation of
the calculated ground current (I
dir
) can be more than 3 A.
i
i
NOTE
When the ground-current calculation is used with the vector method, the deviation of the calculated
ground current is 3 %.
For more information about ground-current calculation, refer to Ground-Current Acquisition, Page 122
4.1.26
4.1.27
Device Functions
4.1 Description
SICAM, Feeder Condition Monitor, Manual 51
E50417-H8940-C580-A4, Edition 03.2019