Setting Of Reverse Zone - ABB RELION RET670 Applications Manual

1MRK 504 163-UUS A
8.13.4.4
8.13.4.5
Transformer protection RET670 2.2 ANSI
Application manual
V I I
+
A A C
Z Z
= = +
AF AC
I I
A A
EQUATION302 V5 EN-US
A
I A
21
ANSI05000457 V2 EN-US
Figure 222: Setting of overreaching zone

Setting of reverse zone

The reverse zone (zone RV) 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. The equation can be used to calculate the reach in reverse direction when the
zone is used for blocking scheme, weak-end infeed, and so on.
> _
Z 1.2 × (Z2 - ZL)
rem
rev
GUID-ABFB1C53-F12A-45D5-90CC-907C9FA0EFC3 V1 EN-US
Where:
ZL is the protected line impedance.
Z2rem is the zone 2 setting (zone used in the POTT scheme) at the remote end of the protected line.
In many applications it might be necessary to consider the enlarging factor due to the
fault current infeed from adjacent lines in the reverse direction in order to obtain
certain sensitivity.
Series compensated and adjacent lines
I I I
+ +
A C B
Z R Z
⋅ + ⋅ =
CF
F
I
A
Z AC
Z CB
F
C
Z CF
I A+ IB
IB
Impedance protection
  
I I
C C
1 Z 1
+ +  ⋅ + +
 
AC C F F
I
 A  
B
ANSI05000457-2-en.vsd
GUID-C08EC148-B90C-4A20-8993-707E63545946 v2
GUID-33C23BA9-5807-4E9E-859A-12D6A76304C0 v1
Section 8

I
+
B
R
 ⋅
F
I
A 
(Equation 349)
(Equation 350)
435