ABB REL670 2.2 IEC, Applications Manual

Page: 284 / 908

( )
1.2 2
³ × -
Zrev ZL Z rem
EQUATION1525 V5 EN-US
(Equation 205)
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
SEMOD154704-48 v1
Parallel line in service – Setting of zone1
SEMOD154704-50 v1
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
SEMOD154704-53 v2
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-earth 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
138 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-US
(Equation 206)
X
0E
X
0
X
m0
+ =
EQUATION554 V1 EN-US
(Equation 207)
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:
0
0 1
2 1 0
m
f
Z
K
Z Z R
= -
× + +
EQUATION1426 V1 EN-US
(Equation 208)
If the denominator in equation 208 is called B and Z0m is simplified to X0m, then
the real and imaginary part of the reach reduction factor for the overreaching zones
can be written as:
Section 8
1MRK 506 369-UEN B
Impedance protection
278 Line distance protection REL670 2.2 IEC
Application manual