Siemens 6MD85, Manual

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generally picks up without direction determination, that is non-directionally. For the advanced stage, the
response can be defined via the
Non-directional pickup
parameter. With the
at volt.< &
mem.empty
setting, the function picks up in such a situation without direction determination. With the
no
setting, the function does not pick up.
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 function uses the threshold-value violation to determine the direc-
tion (forward or reverse) and reports the indication
Direction
. The direction indicated is independent of the
directional mode set for the stage.
The
Release via input signal
setting 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 time delay, and therefore the tripping of the stage, are only enabled if the
>Release delay &
op.
input signal is active.
Pickup and Dropout Behaviors of the Inverse-Time Characteristic Curve According to IEC and ANSI (Basic and
Advanced Stage)
When the input variable exceeds the threshold value by a factor of 1.1, the inverse-time characteristic curve is
processed. An integrating method of measurement summarizes the weighted time. The weighted time results
from the characteristic curve. For this, the time that is associated with the present current value is determined
from the characteristic curve. Once the weighted time exceeds the value 1, the stage operates.
When the measured value falls below the pickup value by a factor of 1.045 (0.95 x 1.1 x threshold value), the
dropout is started. The pickup will be indicated as clearing. You can influence the dropout behavior via setting
parameters. You can select between instantaneous dropout (totalized time is deleted) or dropout according to
the characteristic curve (reduction of totalized time depending on the characteristic curve). The dropout
according to characteristic curve (disk emulation) is the same as turning back a rotor disk. The weighted
reduction of the time is initiated from 0.9 of the set threshold value.
The characteristic curve and associated formulas are shown in the Technical Data.
Minimum Time of the Curve (Advanced Stage)
With the parameter
Min. time of the curve
, you define a minimum operate delay time. The operate
delay time of inverse-time characteristic curve never falls below the minimum operate delay time.
[DwDocp01_040715-01.vsd, 1, en_US]
Figure 7-95 Minimum Operating Time of the Curve
Protection and Automation Functions
7.6 Directional Overcurrent Protection, Phases
682 SIPROTEC 5, High-Voltage Bay Controller, Manual
C53000-G5040-C015-9, Edition 11.2017