Siemens siprotec 7SA522 User Manual page 157

Current Trans-
former Connection
7SA522 Manual
C53000-G1176-C119-2
(any voltage)
Yd5
400 kV/220 kV
220 kV/100 V
feeder
220 kV
Figure 6-9 Busbar voltage, measured across a transformer
• Connection of the U
4
by the overvoltage protection function, refer to Appendix A, Figure 1-15:
Address  is then set: 8 WUDQVIRUPHU = 8[ WUDQVIRUPHU.
It is assumed, that the U
ratio
.
• If the U
input is not required, the following setting is applied:
4
Address  8 WUDQVIRUPHU = 1RW FRQQHFWHG.
Also in this case the factor 8SK  8GHOWD (Address , refer to the above) is
of importance, as it is utilised for the scaling of the measurement and disturbance
recording signals.
The device contains four current measurement inputs, three of which are connected
to the set of current transformers. The fourth current measuring input I
in various ways:
• Connection of the I
4
transformers on the protected feeder (normal connection, refer to Appendix A, Fig-
ure 1-9):
Address  is then set to: , WUDQVIRUPHU = ,Q SURW OLQH and
Address  to ,,SK &7 = 1.
• Connection of the I
4
feeder (e.g. a summation CT, refer to Appendix A, e.g. Figure 1-10).
Address  is then set to: , WUDQVIRUPHU = ,Q SURW OLQH and
Address  LV VHW WR ,,SK &7:
Ratio of earth current transformer
⁄
----------------------------------------------------------------------------------------------------- -
I I =
4 ph CT
Ratio of phase current transformers
Example:
U
L1
U
L2
U
L3
U
E
input to any other voltage signal U
transformer ratio is equal to the phase voltage transfomer
x
input to the earth current in the starpoint of the set of current
input to a separate earth current transformer on the protected
L1
Busbar
L2
400 kV
L3
400 kV
110 V
U
SS
V#ÃU…h†s‚…€r… VƒƒÃU…h†s‚…€r…
=
VƒƒÃ8PII G ²G!
=
VƒƒVyvr ! 
ϕ
= °
VyvrVƒƒÃX9G (
=
, which may be processed
X
may be utilised
4
Functions
6-9