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ANSI05000457-2-en.vsd
F
ANSI05000457 V2 EN
Figure 58: Setting of overreaching zone
Setting of reverse zone
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
78 can be used to calculate the reach in reverse direction when the zone
is used for blocking scheme, weak-end infeed, and so on.
EQUATION1525 V4 EN
(Equation 78)
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.
Setting of zones for parallel line application
Parallel line in service – Setting of zone 1
With reference to section
"Parallel line applications", the zone reach can be set to 85%
of the protected line.
However, influence of mutual impedance has to be taken into account.
1MRK504116-UUS C Section 3
IED application
179
Application manual
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