Siemens 6MD86 - Page 616

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 7-69 I0 Elimination Principle
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
The phase current I
phx-elim.
is necessary for the following protection process.
If the Method of measurement parameter is set to fundamental comp., the I0 elimination is operating.
The currents I
phx-elim.
are available as functional values.
Pickup Delay (Advanced Stage)
If the current exceeds the threshold value, the pickup delay starts. If the threshold is exceeded during the
pickup delay time, the pickup signal is generated.
Blocking of the Stage (Basic and Advanced Stage)
The following blockings reset the picked up stage completely:
•
Via the binary input signal >Block stage from an external or internal source
•
Via the functionality of the dynamic settings (only available in the Advanced function type, see
subtitle Influence of other functions via dynamic settings and chapter 7.4.8.1 Description ).
Protection and Automation Functions
7.4 Overcurrent Protection, Phases
616 SIPROTEC 5, High-Voltage Bay Controller, Manual
C53000-G5040-C015-9, Edition 11.2017