ABB RELION RET670, Applications Manual

Page: 278 / 1016

This means that the reach is reduced in reactive and resistive directions. If the real and
imaginary components of the constant A are equal to equation
128 and equation 129 .
Re( ) 0 (2 1 0 3 ) 0 ( 0 2 1) A R R R Rf X X X
= × × + + × - × + ×
EQUATION1285 V1 EN-US
(Equation 128)
0 1 0 1 0 1 0
Im( ) (2 3 ) (2 ) A X R R R R X X
= × × + + × + × × +
EQUATION1286 V1 EN-US
(Equation 129)
The real component of the KU factor is equal to equation 130 .
Re
Re
Re Im
K
A X
A A
u
m
( )
= +
( )
⋅
( )




+
( )




1
0
2
2 2
EQUATION1287 V3 EN-US
(Equation 130)
The imaginary component of the same factor is equal to equation 131 .
( )
( )
( ) ( )
2
0
2 2
Im
Im
Re Im
m
U
A X
K
A A
×
=
+
é ù é ù
ë û ë û
EQUATION1288 V2 EN-US
(Equation 131)
Ensure that the underreaching zones from both line ends will overlap a sufficient
amount (at least 10%) in the middle of the protected circuit.
8.3.2.7 Tapped line application
M17048-243 v3
Section 8
1MRK 504 163-UUS A
Impedance protection
272 Transformer protection RET670 2.2 ANSI
Application manual