ABB RELION RET670, Applications Manual

Page: 309 / 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
169 and equation 170 .
Re( ) 0 (2 1 0 3 ) 0 ( 0 2 1) A R R R Rf X X X
= × × + + × - × + ×
EQUATION1285 V1 EN-US
(Equation 169)
0 1 0 1 0 1 0
Im( ) (2 3 ) (2 ) A X R R R R X X
= × × + + × + × × +
EQUATION1286 V1 EN-US
(Equation 170)
The real component of the KU factor is equal to equation 171 .
Re
Re
Re Im
K
A X
A A
u
m
( )
= +
( )
⋅
( )




+
( )




1
0
2
2 2
EQUATION1287 V3 EN-US
(Equation 171)
The imaginary component of the same factor is equal to equation 172 .
( )
( )
( ) ( )
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 172)
Ensure that the underreaching zones from both line ends will overlap a sufficient
amount (at least 10%) in the middle of the protected circuit.
8.5.2.8 Tapped line application
SEMOD154680-265 v1
1MRK 504 163-UUS A
Section 8
Impedance protection
Transformer protection RET670 2.2 ANSI 303
Application manual