Setting Of Zones For Parallel Line Application - ABB RELION RET670 Applications Manual

Section 8
Impedance protection
8.9.3.5
340
-
³ ×
Z 1.2 Z2 Z
rev rem L
EQUATION2314 V1 EN-US
Where:
Z is the protected line impedance
L
Z2 is zone 2 setting at remote end of protected line.
rem
In many 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.

Setting of zones for parallel line application

Parallel line in service – Setting of zone 1
With reference to section
of protected line.
However, influence of mutual impedance has to be taken into account.
Parallel line in service – setting of zone 2
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 126 in section "Parallel line
The components of the zero sequence impedance for the overreaching zones must be
equal to at least:
R = R + R
0E 0 m0
EQUATION553 V1 EN-US
X = X + X
0E 0 m0
EQUATION554 V1 EN-US
Check the reduction of a reach for the overreaching zones due to the effect of the zero
sequence mutual coupling. The reach is reduced for a factor:
"Parallel line applications", the zone reach can be set to 85%
applications".
1MRK 504 163-UUS A
(Equation 222)
GUID-F10BF2FF-7B0F-40B0-877B-081E1D5B067B v1
GUID-8EAD617A-D33B-453C-83FC-21E3CFC37CB1 v1
(Equation 223)
(Equation 224)
Transformer protection RET670 2.2 ANSI
Application manual
SEMOD55087-50 v2