ABB RET670 Installation And Commissioning Manual page 63

1MRK 504 088-UEN C
Installation and commissioning manual
L1 L2 L3
(A) (B) (C)
CT 1500/5
Star/Wye
Connected
Protected Object
L1 L2 L3
(A) (B) (C)
IEC07000194 V2 EN
Figure 29: CT connections for restricted earth fault protection
Pos Description
1 Scheme earthing point
Note that it is of outmost importance to insure that only one earthing point
exist in such scheme.
2 One-phase plate with setting resistor and metrosil.
3 Necessary connection for the metrosil. Shown connections are applicable for both types of one-
phase plate.
4 Position of optional test switch for secondary injection into the high impedance differential IED.
5 Necessary connection for setting resistor. Shown connections are applicable for both types of
one-phase plate.
6 How to connect REFPDIF high impedance scheme to one CT input in IED.
7 Transformer input module where this current input is 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
1
2
3
4
5
6
6
7
8
9
10
11
12
N
1
N
4 5
X1
2
1-Ph Plate with Metrosil and Resistor
CTStarPoint shall always be left to the default value ToObject
Section 5
Installing the IED
7
AI01 (I)
SMAI2
AI02 (I)
BLOCK
^GRP2L1
AI03 (I)
^GRP2L2
^GRP2L3
AI04 (I)
^GRP2N
TYPE
AI05 (I)
8
AI06 (I)
4
1 2 3
3
5
9
AI3P
AI1
AI2
AI3
AI4
AIN
IED
IEC07000194_2_en.vsd
57