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If the function block Filter is configured and if you have enabled the filter, the gained RMS value is automati-
cally used.
NOTE
i
i
When the function block Filter is applied, only one 3-phase current measuring point is allowed to be
connected to the 3-phase current interface of the function group.
I0 Elimination (Advanced Stage)
In order to increase the sensitivity for the 2-phase short circuit on the transformer low-voltage side, use the
I0 elimination of the phase currents for the overcurrent-protection application on one transformer.
In order to determine the I0 elimination of the phase currents, the transformer neutral point current I
measured.
[dwsgaocp-230414-01, 1, en_US]
Figure 6-11
The transformer neutral point current I
to the Voltage/current 1-phase. The function group Voltage/current 1-phase must be connected to the func-
tion group Voltage/current 3-phase in which the function Overcurrent protection, phases is being used.
[sccpfoint-230414-01, 1, en_US]
Figure 6-12
In case of an I0 elimination, the following calculations result:
I
= I
- 1/3 I
A-elim.
A
I
= I
- 1/3 I
B-elim.
B
I
= I
- 1/3 I
C-elim.
C
The phase current I
If the Method of measurement parameter is set to fundamental comp., the I0 elimination is applied.
The currents I
phx-elim.
Pickup delay (Advanced Stage)
If the current exceeds the threshold value, the pickup delay is generated. If the threshold remains exceeded
during the pickup delay time, the pickup signal is generated.
SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017
I0 Elimination Principle
is measured via a 1-phase current measuring point that is connected
Y
Connection of the Voltage/Current 1-Phase Function Group with the Neutral Point Input of the
Voltage/Current 3-Phase Function Group
Y
Y
Y
is necessary for the following protection process.
phx-elim.
are available as functional values.
Protection and Automation Functions
6.3 Overcurrent Protection, Phases
must be
Y
331
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