Siemens 6MD85, Manual

Page: 713 / 1256

Directional Comparison Protection (Advanced Stage)
The stage can be used for directional comparison protection. This is set using the
Directional compar-
ison
parameter. With the
yes
setting, the direction indication
Direction
is released and the direction
(forward or reverse) is determined, if the current exceeds the threshold of the stage. The direction indicated is
independent of the directional mode set for the stage.
The
Release via input signal
parameter and the
>Release delay & op.
input signal are available
with directional comparison protection. If the
Release via input signal
parameter is set to
yes
, the
start of the operate delay, and therefore the operate signal of the stage, are only enabled when the
>Release delay & op.
input signal is active.
Influence of Other Functions via Dynamic Settings (Advanced Stage)
If available in the device, the following functions can exert an influence on the overcurrent-protection stage:
•
Automatic reclosing
•
Cold-load pickup detection
•
Binary input signal
The influence of these functions via dynamic settings is described in chapter 7.7.10 Influence of Other Func-
tions via Dynamic Settings .
Application and Setting Notes
Parameter:
Directional mode
•
Default setting
(_:4861:105) Directional mode
=
forward
You can use the
Directional mode
parameter to define the directional mode of the stage.
Parameter Value Description
forward
Select this setting if the stage is to work in forward direction (in the direction
of the line).
reverse
Select this setting if the stage is to work in reverse direction (in the direction
of the busbar).
Parameter:
Method of measurement
•
Recommended setting value
(_:4861:8) Method of measurement
=
fundamental comp.
With the
Method of measurement
parameter, you define whether the stage uses the
fundamental
comp.
(standard method) or the calculated
RMS value
.
Parameter Value Description
fundamental comp.
Select this method of measurement if harmonics or transient current peaks
are to be suppressed.
Siemens recommends using this method as the standard method.
RMS value
Select this method of measurement if you want the stage to take harmonics
into account (for example, at capacitor banks). Consider that aperiodic DC
components present in the secondary circuit are measured and can cause
an overfunction.
For this method of measurement, do not set the
threshold value
of the
stage to less than 0.1 I
rated,sec
. If currents from more than one measuring
point are added up in the current interface of a function group, the setting
value should not be set lower than 0.1 I
rated,sec
multiplied by the number of
added currents.
7.7.5.2
Protection and Automation Functions
7.7 Directional Overcurrent Protection, Ground
SIPROTEC 5, High-Voltage Bay Controller, Manual 713
C53000-G5040-C015-9, Edition 11.2017