Siemens 6MD85, Manual

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Application and Setting Notes
Apart from the operate curve, this type of stage is identical to the ground-fault protection type with inverse-
time delay according to IEC and ANSI (advanced function type) (see chapter
7.7.6.1 Description ).
This section only discusses the nature of the operate curve. For further functionality, refer to chapter
7.7.6.2 Application and Setting Notes .
Stage Type Selection
If the operate delay is to be dependent on the current level according to a logarithmic characteristic curve,
select this stage type.
Dynamic Settings:
Threshold
•
Default setting
(_:3) Threshold
=
1.20 A
Define the pickup value corresponding to the application. In doing so, for time-graded stages, the settings of
the superordinate and of the subordinate stages in the time-grading chart must be taken into consideration.
Parameter:
Threshold multiplier
•
Default setting
(_:116) Threshold multiplier
=
1.1
You can use the
Threshold multiplier
parameter to define the beginning of the characteristic curve on
the current axis (in relation to the threshold value).
General information cannot be provided. Define the value corresponding to the application.
EXAMPLE
Threshold
(Secondary current) I
thresh
= 1.2 A
Threshold multiplier
I
mul
= 1.1
Pickup value (Secondary current) I
PU
= 1.2 A ×1.1 = 1.32 A
Dynamic Settings:
Time dial
•
Default setting
(_:6) Time dial
=
1.250 s
You can use the
Time dial
parameter to change the slope of the characteristic curve.
General information cannot be provided. Define the value corresponding to the application.
Parameter:
Max. time of the curve
•
Default setting
(_:114) Max. time of the curve
=
5.800 s
The parameter
Max. time of the curve
determines the initial value of the characteristic curve (for 3I0 =
Threshold
).
General information cannot be provided. Define the value corresponding to the application.
Parameter:
Min. time of the curve
•
Default setting
(_:113) Min. time of the curve
=
1.200 s
The parameter
Min. time of the curve
determines the lower time limit (at high currents).
General information cannot be provided. Define the value corresponding to the application.
Parameter:
Additional time delay
•
Recommended setting value
(_:115) Additional time delay
=
0 s
You can set an additional current-independent time delay. This additional delay is intended for special applica-
tions.
7.7.7.2
Protection and Automation Functions
7.7 Directional Overcurrent Protection, Ground
732 SIPROTEC 5, High-Voltage Bay Controller, Manual
C53000-G5040-C015-9, Edition 11.2017