Siemens SIPROTEC 4 7UT6 Series Manual page 61

correct display and transmission of measured values (voltages, powers). Similar considerations apply to
address 409 UN-PRI U4.
Current Transformer Data for 3-phase Measuring Locations
The rated primary operational currents for the protected object and its sides derive from the object data. The
data of the current transformer sets at the sides of the protected object generally differ slightly from the
object data before-described. They can also be completely different. Currents have to have a clear polarity to
ensure correct function of the differential protection and restricted earth fault protection as well as for correct
display of operational measured values (power etc.).
Therefore the device must be informed about the current transformer data. For 3-phase protected objects, this
is done by entering rated currents and the secondary starpoint position of the current transformer sets.
In address 512 IN-PRI CT M1 the rated primary current of the current transformer set of measuring location
M1 is set, in address 513 IN-SEC CT M1 the rated secondary current. Please make sure that the sides were
defined correctly (see Section
Locations"). Please also make sure that the rated secondary transformer currents match the setting for the
rated currents of these measuring inputs of the device. Otherwise the device will calculate incorrect primary
data, and malfunction of the differential protection may occur.
Indication of the starpoint position of the current transformers determines the polarity of the currents. To
inform the device of the starpoint position in relation to the measuring location 1, use address 511 STRPNT-
>OBJ M1 (starpoint versus object: YES or NO).
SIPROTEC 4, 7UT6x, Manual
C53000-G1176-C230-5, Edition 09.2016
2.1.4 Power System Data 1, margin heading "Assignment of 3-phase Measuring
Figure 2-13 shows some examples for this setting.
Functions
2.1 General
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