A
B
Z<
C
I
C
Z
AC
Z
CB
Z
CF
I
A
+ I
C
IEC09000256-2-en.vsd
F
I
A
I
B
IEC09000256 V2 EN-US
Figure 62:
Setting of overreaching zone
7.1.3.4
Setting of reverse zone
GUID-B633CF2C-28B2-4FDD-BE0E-D09CA434F01F v1
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 55)
Where:
ZL
is the protected line impedance
Z2rem is zone 2 setting at remote end of protected line.
In many applications it might be necessary to consider the enlarging factor due to
fault current infeed from adjacent lines in the reverse direction in order to obtain
certain sensitivity.
7.1.3.5
Setting of zones for parallel line application
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Parallel line in service – Setting of zone 1
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With reference to section
, the zone reach can be set to
85% of the protected line.
However, influence of mutual impedance has to be taken into account.
Section 7
1MRK 505 393-UEN B
Impedance protection
124
Line differential protection RED650 2.2 IEC
Application manual
Summary of Contents for RED650
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