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Functions
2.1 General
2.1.3
Power System Data 1
The device requires some plant and power system data in order to be able to adapt its functions accordingly,
dependent on the actual application. The data required include for instance rated data of the substation and the
measuring transformers, polarity and connection of the measured quantities, if necessary features of the circuit
breakers, and others. Furthermore, there is a number of settings associated with several functions rather than
a specific protection, control or monitoring function. The Power System Data 1 can only be changed from a PC
running DIGSI and are discussed in this section.
2.1.3.1 Setting Notes
Current Transformer Polarity
At address 201 CT Starpoint, the polarity of the wye-connected current transformers is specified (the fol-
lowing figure applies accordingly to two current transformers). This setting determines the measuring direction
of the device (forward = line direction). A change in this setting also results in a polarity reversal of the earth
current inputsI
Figure 2-2
Nominal Values of the Transformers
In addresses 203 Unom PRIMARY and 204 Unom SECONDARY the device obtains information on the primary
and secondary rated voltage (phase-to-phase voltage) of the voltage transformers.
It is important to ensure that the secondary CT nominal current matches the rated current of the device, other-
wise the device will incorrectly calculate primary data.
Correct entry of the primary data is a prerequisite for the correct computation of operational measured values
with primary magnitude. If the settings of the device are performed with primary values using DIGSI, these
primary data are an indispensable requirement for the correct function of the device.
30
.
E
Polarity of current transformers
SIPROTEC, 7VK61, Manual
C53000-G1176-C159-3, Release date 05.2009
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