Siemens siprotec 7SA6 User Manual

Functions
6-10 7SA6 Manual
C53000-G1176-C133-1
This is independent on whether the device has a normal measured current input for
I
4
or a sensitive measured current input for I
4
(for sensitive earth fault detection in
non-earthed systems)
Example:
Phase current transformers 500 A/5 A
Cable core balance current transformer 60 A/1 A
• Connection of the I
4
input to the earth current of the parallel line (for parallel line
compensation of the distance protection and/or fault location function, refer to
Appendix A, Figure A-22):
Address  is then set to: ,WUDQVIRUPHU = ,QSDUDOOLQH and
usually address  is set to ,,SK&7 = 1.
If the set of current transformers on the parallel line however has a different ratio to
those on the protected line, this must be taken into account in address :
Address  is then set so that: ,WUDQVIRUPHU = ,QSDUDOOLQH and
Address  so that ,,SK&7 = I
N paral. line
/I
N prot. line
.
Example:
Current transformers on protected feeder 1200 A
Current transformers on parallel feeder 1500 A
• Connection of the I
4
input to the neutral current of a power transformer; this
connection can be used for the polarisation of the directional earth fault protection
(refer to Appendix A, Figure A-23):
Address  is then set to: ,WUDQVIRUPHU = ,<VWDUSRLQW, and
address ,,SK&7 according to the ratio of the transformation ratios of the
current transformer in the transformer neutral and the set of current transformers on
the protected feeder.
• If the I
4
input is not required, the following settings are applied:
Address  ,WUDQVIRUPHU = 1RWFRQ QHFWHG ,
Address  ,,SK&7 is then irrelevant.
In this case the zero sequence current for the protection functions is computed by
means of the sum of the phase currents.
Rated Frequency Address  5DWHG)UHTXHQF\ corresponds to the frequency at which the power
system operates. The preset value is dependent on the model number of the relay
purchased, and must be in accordance with the nominal frequency of the power
system.
System Starpoint The system starpoint must be observed for the correct processing of earth faults and
double earth faults. Therefore address  6\VWHP6WDUSRLQW 6ROLG(DUWKHG
or 3HWHUVRQ&RLOHDUWKHGor ,VRODWHG must be set correspondingly. For low-
resistant earthed systems set HDUWKHG
I
4
I
ph CT
⁄
Ratio of earth current transformer
Ratio of phase current transformers
------------------------------------------------------------------------------------------------------
=
I
4
I
ph CT
⁄
60 1 ⁄
500 5 ⁄
-----------------
0.600 ==
I
4
I
ph
⁄
1500
1200
-------------
1.250 ==

Siemens siprotec 7SA6 Specifications

General

Brand	Siemens
Model	siprotec 7SA6
Category	Relays
Language	English