Additional Time Delay (Advanced Stage)
With the parameter Additional time delay, you define a definite-time delay in addition to the inverse-
time delay. With this setting, the whole curve is shifted on the time axis by this additional definite time.
Method of Measurement (Basic and Advanced Stage)
You use the Method of measurement parameter to define whether the stage uses the fundamental
comp. or the calculated RMS value.
•
Measurement of the fundamental component:
This method of measurement processes the sampled current values and filters out the fundamental
component numerically.
•
Measurement of the RMS value:
This method of measurement determines the current amplitude from the sampled values according to
the defining equation of the RMS value. Harmonics are included in the analysis.
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 applications on one transformer.
In order to determine the I0 elimination of the phase currents, the transformer neutral point current I
Y
must be
measured.
[dwsgaocp-230414-01, 1, en_US]
Figure 6-17 I0 Elimination Principle
The transformer neutral point current I
Y
is measured via a 1-phase current measuring point that is connected
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 used.
[sccpfoint-230414-01, 1, en_US]
Figure 6-18 Connection of the Function Group Voltage/Current 1-Phase with the Neutral Point Input of the
Voltage/Current 3-Phase Function Group
In case of an I0 elimination, the following calculations must be considered:
I
A-elim.
= I
A
- 1/3 I
Y
I
B-elim.
= I
B
- 1/3 I
Y
I
C-elim.
= I
C
- 1/3 I
Y
Protection and Automation Functions
6.3 Overcurrent Protection, Phases
342 SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017
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