ABB RELION RET670, Applications Manual

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A
B
21
C
I A
IB
Z AC
Z CB
Z CF
IA+ IB
ANSI05000457-2-en.vsd
F
ANSI05000457 V2 EN-US
Figure 113:
8.1.3.4 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
82 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 82)
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.
8.1.3.5 Series compensated and adjacent lines
SEMOD168247-142 v2
Directional control
SEMOD168247-145 v2
The directional function (ZDSRDIR) which is able to cope with the condition at
voltage reversal, shall be used in all IEDs with conventional distance protection
1MRK 504 163-UUS A
Section 8
Impedance protection
Transformer protection RET670 2.2 ANSI 237
Application manual