Hitachi 670 Series User Manual

6.1.1.4 Connection examples for high impedance differential protection
GUID-8C58A73D-7C2E-4BE5-AB87-B4C93FB7D62B v5
WARNING! USE EXTREME CAUTION! Dangerously high voltages might be present on this
equipment, especially on the plate with resistors. De-energize the primary object protected
with this equipment before connecting or disconnecting wiring or performing any
maintenance. The plate with resistors should be provided with a protective cover, mounted in
a separate box or in a locked cubicle. National law and standards shall be followed.
Connections for three-phase high impedance differential protection
GUID-C12CCAAF-5AE5-4A9C-AC9C-F56A66FD2C14 v8
Generator, reactor or busbar differential protection is a typical application for three-phase high
impedance differential protection. Typical CT connections for three-phase high impedance differential
protection scheme are shown in figure
24.
L1
(A)
L2
(B)
L3
(C)
Protected Object
CT 1200/1
Star/Wye
Connected
L1
(A)
L2
(B)
L3
(C)
CT 1200/1
Star/Wye
Connected
7
8
9
1
0
1
1
1
2
1
2
3
4
5
6
AI01
(I)
AI02
(I)
AI03
(I)
AI04
(I)
AI05
(I)
AI06
(I)
7
6
X1
R4 R5 R6
1
2
1
2
1
2
11 12 13 14
U U U
R1
1
3
4
2
1
3
R2
2
4
1
3
R3
2
4
1 2 3 4 5 6 7
L1 (A)
L2 (B)
L3 (C)
N
3-Ph Plate with Metrosils and Resistors
2
3
5
4
X X
L1 (A)
L2 (B)
L3 (C)
N
1
IED
SMAI2
BLOCK
REVROT
^GRP2_A
^GRP2_B
^GRP2_C
^GRP2_N
G2AI3P
G2AI1
G2AI2
G2AI3
G2AI4
G2N
ANSI09000169-4-en.vsdx
ANSI09000169 V4 EN-US
Figure 24: CT connections for high impedance differential protection
Pos
Description
1 Scheme grounding point
It is important to insure that only one grounding point exist in this scheme.
2 Three-phase plate with setting resistors and metrosils. Protective ground is a separate 4 mm screw terminal on
the plate.
3 Necessary connection for three-phase metrosil set.
4 Position of optional test switch for secondary injection into the high impedance differential IED.
Section 6 1MRK514026-UUS Rev. P
Connecting
46 670 series
Installation manual
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Hitachi 670 Series Specifications

General

Brand	Hitachi
Model	670 Series
Category	Control Unit
Language	English