down during faults. The zone2 must not be reduced below 120% of the protected line section.
The whole line must be covered under all conditions.
The requirement that the zone 2 shall not reach more than 80% of the shortest adjacent line at
remote end is highlighted with a simple example below.
If a fault occurs at point F (as shown in figure
, also for the explanation of all abbreviations
used), the IED at point A senses the impedance:
Z
V
I
Z
I
I
I
Z
I
I
I
I
R
Z
I
I
Z
AF
A
A
AC
A
C
A
CF
A
C
B
A
F
AC
C
A
C
=
=
+
+
⋅
+
+
+
⋅
=
+
+
⋅
1
F
F
C
B
A
F
I
I
I
R
+
+
+
⋅
1
EQUATION302 V5 EN-US
(Equation 94)
A
B
Z<
C
I A
IC
Z AC
Z CB
Z CF
I A+ IC
IEC05000457-2-en.vsd
F
IB
IEC05000457 V2 EN-US
Figure 115: Setting of overreaching zone
7.1.3.4
Setting of reverse zone
SEMOD168247-33 v2
The reverse zone is applicable for purposes of scheme communication logic, current reversal
logic, weak-end-infeed logic, and so on. The same applies to the back-up protection of the bus
bar or power transformers. It is necessary to secure, that it always covers the overreaching
zone, used at the remote line IED for the telecommunication purposes.
Consider the possible enlarging factor that might exist due to fault infeed from adjacent lines.
Equation
can be used to calculate the reach in reverse direction when the zone is used for
blocking scheme, weak-end infeed and so on.
(
)
1.2
2
³
×
-
Zrev
ZL Z rem
EQUATION1525 V5 EN-US
(Equation 95)
Where:
ZL
is the protected line impedance
Z2rem is zone2 setting at remote end of protected line.
In some applications it might be necessary to consider the enlarging factor due to fault
current infeed from adjacent lines in the reverse direction to obtain certain sensitivity.
7.1.3.5
Series compensated and adjacent lines
SEMOD168247-142 v2
1MRK 505 343-UEN B
Section 7
Impedance protection
181
Application manual
Содержание Relion 670 series
Страница 1: ...RELION 670 SERIES Line differential protection RED670 Version 2 1 IEC Application manual...
Страница 2: ......
Страница 40: ...34...
Страница 64: ...58...
Страница 150: ...144...
Страница 406: ...400...
Страница 472: ...466...
Страница 494: ...488...
Страница 512: ...506...
Страница 524: ...518...
Страница 604: ...598...
Страница 686: ...680...
Страница 718: ...712...
Страница 722: ...716...
Страница 758: ...752...
Страница 759: ...753...