ABB RET670 Applications Manual page 149

1MRK504116-UUS C
Application manual
L1 L2 L3
(A) (B) (C)
CT 1500/5
Star/Wye
Connected
Protected Object
L1 L2 L3
(A) (B) (C)
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.
1
2
3
4
5
6
6
7
8
9
10
11
12
N
1
N
4 5
X1
2
3
1-Ph Plate with Metrosil and Resistor
Section 3
IED application
7
9
AI01 (I)
AI02 (I) SMAI2
BLOCK AI3P
^GRP2_A AI1
AI03 (I)
^GRP2_B AI2
^GRP2_C AI3
AI04 (I) ^GRP2_N AI4
TYPE AIN
AI05 (I)
8
AI06 (I)
IED
4
1 2 3
5
ANSI09000170_2_en.vsd
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