ABB Relion 670 series - Setting of Zones for Parallel Line Application

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
208 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 2³ × -Zrev ZL Z rem
EQUATION1525 V5 EN (Equation 208)
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 in order to obtain certain
sensitivity.
8.5.3.5 Setting of zones for parallel line application
Parallel line in service – Setting of zone1
With reference to section "Parallel line applications", the zone reach can be set to 85% of
protected line.
Parallel line in service – setting of zone2
Overreaching zones (in general, zones 2 and 3) must overreach the protected circuit in all
cases. The greatest reduction of a reach occurs in cases when both parallel circuits are in
service with a single phase-to-ground fault located at the end of a protected line. The
equivalent zero-sequence impedance circuit for this case is equal to the one in figure
140
in section "Parallel line applications".
The components of the zero-sequence impedance for the overreaching zones must be
equal to at least:
R
0E
R
0
R
m0
+=
EQUATION553 V1 EN (Equation 209)
X
0E
X
0
X
m0
+=
EQUATION554 V1 EN (Equation 210)
Section 8 1MRK 506 369-UUS -
Impedance protection
296 Line distance protection REL670 2.2 ANSI
Application manual