ABB Relion 670 series - Page 64

8 Transformer input module, where the current inputs are located.
Note that the CT ratio for high impedance differential protection application
must be set as one.
• For main CTs with 1A secondary rating the following setting values shall be entered:
CTprim = 1A and CTsec = 1A
• For main CTs with 5A secondary rating the following setting values shall be entered:
CTprim = 5A and CTsec = 5A
• The parameter CTStarPoint shall be always left to the default value ToObject .
9 Three connections made in the Signal Matrix, which connect these three current inputs to the
first three input channels of the preprocessing function block (10). For high impedance
differential protection preprocessing function block in 3ms task shall be used.
10 Preprocessing block, to digitally filter the connected analogue inputs. Preprocessing block
outputs AI1, AI2 and AI3 shall be connected to three instances of 1Ph high impedance
differential protection HZPDIF function blocks, for example instance 1, 2 and 3 of HZPDIF in
the configuration tool.
Connections for 1Ph High impedance differential protection HZPDIF
Restricted earth fault protection REFPDIFis a typical application for 1Ph High
impedance differential protection HZPDIF. Typical CT connections for high
impedance based REFPDIF protection scheme are shown in figure
32.
L1
(A)
L2
(B)
L3
(C)
Protected Object
CT 1500/5
Star/Wye
Connected
7
8
9
10
11
12
1
2
3
4
5
6
AI01 (I)
AI02 (I)
AI03 (I)
AI04 (I)
AI05 (I)
AI06 (I)
6
7
8
IED
X1
R
1
1
2
4 5
U
R
2
1
3
4
2
1 2 3
N
1-Ph Plate with Metrosil and Resistor
2
3
5
4
9
N
L1
(A)
L2
(B)
L3
(C)
C
T
1
5
0
0
/
5
1
IEC07000194_2_en.vsd
AI3P
AI1
AI2
AI3
AI4
AIN
SMAI2
BLOCK
^GRP2L1
^GRP2L2
^GRP2L3
^GRP2N
TYPE
IEC07000194 V2 EN
Figure 32: CT connections for restricted earth fault protection
Section 5 1MRK 502 029-UEN A
Installing the IED
58
Installation and commissioning manual