Siemens siprotec 7SA522 - Page 43

2.1 General
43
7SA522 Manual
C53000-G1176-C155-3
Example:
Phase current transformers 500 A/5 A
Core balance CT 60 A/1 A
• Connection of the I
4
input to the earth current of a parallel line (for parallel line com-
pensation of the distance protection and/or fault location):
Address  is then set to: ,WUDQVIRUPHU = ,QSDUDOOLQH and usually
address  ,,SK&7 = 1.
If the set of current transformers on the parallel line however has a different trans-
formation ratio to those on the protected line, this must be taken into account in
address :
Address  is then set to: ,WUDQVIRUPHU = ,QSDUDOOLQH and address
 ,,SK&7 = I
N paral. line
/ I
N prot. line
Example:
Current transformers on protected line 1200 A
Current transformers on parallel line 1500 A
• Connection of the I
4
input to the starpoint current of a transformer; this connection
is occasionally used for the polarisation of the directional earth fault protection:
Address  is then set to: ,WUDQVIRUPHU = ,<VWDUSRLQW, and address 
,,SK&7 is according to transformation ratio of the starpoint transformer to the
transformer set of the protected line.
• If the I
4
input is not required, set:
Address  ,WUDQVIRUPHU = 1RWFRQQHFWHG,
Address  ,,SK&7 is then irrelevant.
In this case, the neutral current is calculated from the sum of the phase currents.
Rated Frequency The nominal frequency of the system is set in address  5DWHG)UHTXHQF\. The
presetting according to the ordering code (MLFB) only needs to be changed if the
device is applied in a region different to the one indicated when ordering. You can set
+] or +].
System Starpoint The manner in which the system starpoint is earthed must be considered for the
correct processing of earth faults and double earth faults. Accordingly, set for address
 6\VWHP6WDUSRLQW = 6ROLG(DUWKHG, 3HWHUVRQ&RLO or ,VRODWHG. For
low-resistant earthed systems set 6ROLG(DUWKHG.
Phase Rotation Use address  3+$6(6(4 to change the default setting (/// for clockwise
rotation) if your power system has a permanent anti-clockwise phase sequence (/
//).
Distance Unit Address  'LVWDQFH8QLW determines the distance unit (NP or 0LOHV) for the
fault location indications. This parameter is not relevant if fault detection is not avail-
able. Changing the distance unit will not result in an automatic conversion of the