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
IED
X1
R1
1
2
4 5
V
R2
1
3
4
2
1 2 3
N
1-Ph Plate with Metrosil and Resistor
2
3
5
4
N
L1
(A)
L2
(B)
L3
(C)
CT 1500
/5
1
ANSI09000170-5-en.vsdx
SMAI2
BLOCK
REVROT
^GRP2_A
^GRP2_B
^GRP2_C
^GRP2_N
G2AI3P
G2AI1
G2AI2
G2AI3
G2AI4
G2N
ANSI09000170 V5 EN
Figure 52: CT connections for restricted earth fault protection
Pos
Description
1 Scheme grounding point
Ensure that only one grounding point exists in this scheme.
2 One-phase plate with stabilizing resistor and metrosil. Protective ground is a separate 4 mm screw
terminal on the plate.
3 Necessary connection for the metrosil.
4 Position of optional test switch for secondary injection into the high impedance differential IED.
5 Necessary connection for stabilizing resistor.
6 How to connect the high impedance restricted earth fault protection scheme to one CT input in IED.
7.1.4 Setting guidelines
The setting calculations are individual for each application. Refer to the different
application descriptions below.
Section 7 1MRK 506 369-UUS -
Differential protection
144 Line distance protection REL670 2.2 ANSI
Application manual
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