Siemens 6MD85, Manual

Page: 858 / 1256

Parameter: Tilt power characteristic
•
Recommended setting value
(_:6271:103) Tilt power characteristic
=
+70°
The
Tilt power characteristic
parameter is used to incline the pickup characteristic. In the above
example, an inclination is required. The setting value is
+70°
(for a definition of the sign, see Figure 7-172 ).
Parameter: Dropout delay
•
Recommended setting value
(_:6271:7) Dropout delay
=
20 ms
The
Dropout delay
parameter maintains the pickup even if the measured value drops momentarily below
the threshold value. A delay is required for very low pickup values to prevent a so-called chattering of the
function. In the example, the setting value is 20 ms.
Parameter: Operate delay
•
Recommended setting value
(_:6271:6) Operate delay
=
100 ms
The
Operate delay
must be set for the specific application. In the example, a setting value of 100 ms has
been selected.
Setting Notes for the Reactive Power Stage
Stage Type
In the example, the reactive power is to be monitored if it falls below the threshold. In the 3-phase circuit
breaker (P, Q) function, work with the stage type Power Q<.
Parameter: Measured value
•
Recommended setting value
(_:6331:105) Measured value
=
positive seq. power
The
Measured value
parameter is used to specify which measured power value is evaluated. For 3-phase
measurement, Siemens recommends to evaluate the positive-sequence system power.
Parameter: Threshold
•
Recommended setting value
(_:6331:3) Threshold
=
0 %
The
Threshold
parameter is used to define the pickup threshold of the reactive power stage. In the example,
the pickup characteristic runs across the point of origin of the coordinates. Set the parameter
Threshold
to
0 %
.
i
i
NOTE
If you use several settings groups, consider the following:
•
The dropout value of a stage must have the same sign in all settings groups.
•
Switching from a positive dropout value to a negative dropout value or vice versa is not allowed. As a
result, DIGSI reports an inconsistency.
•
If you want to change the sign of the dropout value of a stage in an additional settings group, instan-
tiate a new stage and enable it. If the new stage should not be effective in another settings group,
disable the stage there.
Parameter: Dropout ratio
•
Recommended setting value
(_:6331:101) Dropout ratio
=
0.95
A hysteresis of 5 % is sufficient for most applications. The setting value for the lower stage is therefore 0.95.
7.22.7
Protection and Automation Functions
7.22 Power Protection (P,Q), 3-Phase
858 SIPROTEC 5, High-Voltage Bay Controller, Manual
C53000-G5040-C015-9, Edition 11.2017