Siemens 6MD85, Manual

Page: 753 / 1256

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.
Method of Measurement
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.
Blocking of the Stage
The picked up stage can reset completely via the binary input signal
>Block stage
.
Blocking of the Time Delay
You can use the binary input signal
>Block delay & op.
to prevent the start of the time delay and thus
also tripping. A running time delay is reset. The pickup is reported and a fault is opened.
Blocking of Tripping via the Device-Internal Inrush-Current Detection Function
With the
Blk. w. inrush curr. detect.
parameter, you can block the operate indication of the stage
for a threshold-value violation due to the inrush current. In case of a blocking, the stage picks up. The start of
the time delay and the operate indication are blocked. The function signals this through a corresponding indi-
cation. If the blocking drops out and the threshold value of the stage is still exceeded, the time delay is
started. When complete, the stage generates an operate indication.
Blocking of tripping with the Inrush-current detection function is possible only if the following conditions
have been met:
•
The central Inrush-current detection function has to be available in another protection function group
with 3-phase current measurement.
•
You have to connect the protection function group with 1-phase current measurement to the protection
function group with 3-phase current measurement. You connect protection function groups in the
DIGSI 5 Project Tree → Name of the device → Function group connections.
Application and Setting Notes
Parameter:
Method of measurement
•
Recommended setting value
(_:12691:8) 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.
7.8.4.2
Protection and Automation Functions
7.8 Overcurrent Protection, 1-Phase
SIPROTEC 5, High-Voltage Bay Controller, Manual 753
C53000-G5040-C015-9, Edition 11.2017