ABB RET670 - Page 149

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
V
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
ANSI09000170_2_en.vsd
AI3P
AI1
AI2
AI3
AI4
AIN
SMAI2
BLOCK
^GRP2_A
^GRP2_B
^GRP2_C
^GRP2_N
TYPE
ANSI09000170 V2 EN
Figure 39: CT connections for restricted earth fault protection
Pos
Description
1 Scheme grounding point
Note that it is of outmost importance to insure that only one grounding point
exist in such scheme.
2 One-phase plate with stabilizing 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 stabilizing resistor. Shown connections are applicable for both types of one-
phase plate.
6 How to connect REFPDIF (87N) high impedance scheme to one CT input in IED.
1MRK504116-UUS C Section 3
IED application
143
Application manual