Siemens SIPROTEC 4 7SJ61 Manual page 37

[7sj62-64-mess-2erdstroeme-20070301, 1, en_US]
Figure 2-4
The phase currents Ι
(terminals Q5, Q6). At the fourth input (terminals Q7, Q8) the ground current Ι
in this case the ground current of the line. A second ground current, in this case the transformer neutral point
current, is connected to the second current input Ι
The settings A,G2,C,G; G->B or A,G2,C,G; G2->B must be used here. Both define the connection of a
ground current Ι
. In case of A,G2,C,G; G->B, the phase current Ι
Ι
B
measured ground current Ι
current Ι is determined by phase currents Ι
B
current input. The setting must be set according to system requirements.
The assignment of the protection functions to the ground current inputs in special connections is set out in
the following table.
Current Input
Ι
N2
SIPROTEC 4, 7SJ61, Manual
C53000-G1140-C210-6, Edition 05.2016
Measurement of two ground currents, example
and Ι must be connected to the first current input (terminals Q1, Q2) and to the third
A C
at the second current input (terminals Q3, Q4). The settings only differ in the calculation of
N2
or Ι at the fourth current input. In case of A,G2,C,G; G2->B, the phase
N NS
Time overcurrent protection ground (Section
51N)
(terminals Q3, Q4).
N2
is determined by phase currents Ι
B
and Ι as well as the measured ground current Ι
A C
Function
2.2 Overcurrent Protection 50, 51, 50N,
Functions
2.1 General
or Ι is connected as usual,
N NS
and Ι as well as the
A C
at the second
N2
37