Functions
2.5 Power System Data 1
SIPROTEC, 7UM62, Manual
C53000-G1176-C149-7, Release date 03.2010
54
Figure 2-9 Current transformer starpoints in transverse differential protection - Example
Nominal Values of the Transformers on Side 1
At addresses 202 IN-PRI I-SIDE1 and 203 IN-SEC I-SIDE1 information is entered regarding the primary
and secondary nominal currents of the CTs of side 1. 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 calculate incorrectly
primary data.
Nominal Values of the Transformers on Side 2
At addresses 211 IN-PRI I-SIDE2 and 212 IN-SEC I-SIDE2 information is entered regarding the primary
and secondary nominal currents of the CTs of side 2. 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 calculate incorrectly
primarydata.
W0 Correction Angle
A correction of the angle faults of the current and voltage transformers is particularly important with regard to
reverse power protection, as in this case a very low active power is computed from a very high apparent power
(for small cos ϕ).
At address 204 CT ANGLE W0 a constant correction angle can be entered for the CTs of side 2.
The angle fault difference Δϕ between the current and voltage transformers is particularly important in this con-
text. As a correction, the sum of the mean angle errors of the current and voltage transformers is set. The cor-
rection value can be determined during machine commissioning (see Section Installation and Commissioning).
Transformation Ratios IEE
For the conversion of the ground currents Iee in primary quantities, the device requires the primary/secondary
transformation ratio of the earth CTs. The transformation ratio for input 1 is set at the address 205 FACTOR
IEE1, the ratio for input 2 at 213 FACTOR IEE2 .
Nominal Values of Voltage Transformers
At addresses 221 Unom PRIMARY and 222 Unom SECONDARY, information is entered regarding the primary
nominal voltage and secondary nominal voltages (phase-to-phase) of the connected voltage transformers.
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