2 Functions
40
7SA522 Manual
C53000-G1176-C155-3
2.1.3 Power System Data 1
The device requires certain system and power system data so that it can adapt the
implemented functions according to this data. This comprises e.g. nominal system
data, nominal data of instrument transformers, polarity and connection type of mea-
sured values, in certain cases circuit breaker properties, etc. Furthermore, there are
a number of settings associated with all functions rather than a specific protection,
control or monitoring function. These data can only be changed from a PC running
DIGSI
®
and are discussed in this Subsection.
2.1.3.1 Setting Notes
General In DIGSI
®
double-click Settings to display the available data. A dialog box with tabs
CT's, VT's, Power System and Breaker will open under 3RZHU6\VWHP'DWD in
which you can configure the individual parameters. Thus, the following subsections
are structured accordingly.
Current
Transformer
Polarity
At address &76WDUSRLQW, the polarity of the wye-connected current transform-
ers is specified (the following figure also goes for two current transformers). This
setting determines the measuring direction of the device (forwards = line direction).
Modifying this setting also results in a polarity reversal of the earth current inputs I
E
or
I
EE
.
Figure 2-2 Polarity of Current Transformers
Nominal Values of
the Transformers
In addresses 8QRP35,0$5< and 8QRP6(&21'$5< the device obtains in-
formation on the primary and secondary rated voltage (phase-to-phase voltage) of the
voltage transformers.
It is important to ensure that the rated secondary current of the current transformer
matches the rated current of the device, otherwise the device will incorrectly calculate
primary amperes.
The correct primary data are required for the calculation of the proper primary infor-
mation of the operational measured values. If the settings of the device are performed
with primary values using DIGSI
®
, these primary data are an indispensable require-
ment for the fault-free operation of the device.
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