Tapped Line Application - ABB RELION RET670 Applications Manual

1MRK 504 163-UUS A
8.5.2.8
Transformer protection RET670 2.2 ANSI
Application manual
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
= × × +
Re( ) A R 0 (2 R 1
EQUATION1285 V1 EN-US
= × × +
Im( ) A X (2 R
0 1
EQUATION1286 V1 EN-US
The real component of the KU factor is equal to equation 171.
( )
Re 1
K
= +
u

Re

EQUATION1287 V3 EN-US
The imaginary component of the same factor is equal to equation 172.
( )
×
Im A X
( )
=
Im K
U
( )
2
é ù
+
Re A
ë û
EQUATION1288 V2 EN-US
Ensure that the underreaching zones from both line ends will overlap a sufficient
amount (at least 10%) in the middle of the protected circuit.

Tapped line application

+ × - ×
R 0 3 Rf ) X 0 ( 0 2 X
+ × + × ×
R 3 R ) R (2 X
0 1 0
2
( )
Re
A X
⋅
m 0
2 2
( ) ( )
  
A Im A
+
  
2
m 0
( )
2
é ù
Im A
ë û
Impedance protection
169 and equation 170.
+ ×
X 1)
+
X )
1 0
Section 8
(Equation 169)
(Equation 170)
(Equation 171)
(Equation 172)
SEMOD154680-265 v1
303