ABB RED650, Applications Manual

Page: 131 / 454

Parallel line in service – setting of zone 2
GUID-98D11A72-C5BE-4C67-ADB5-95124C2AF987 v1
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
56 in section Parallel line in service .
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 56)
X
0E
X
0
X
m0
+ =
EQUATION554 V1 EN-US
(Equation 57)
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 58)
If the denominator in equation 58 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:
( )
( )
( ) ( )
2 2
0 Re
Re 0 1
Re Im
X m B
K
B B
×
= -
+
EQUATION1427 V2 EN-US
(Equation 59)
( )
( )
( ) ( )
2 2
0 Im
Im 0
Re Im
X m B
K
B B
×
=
+
EQUATION1428 V2 EN-US
(Equation 60)
Parallel line is out of service and earthed in both ends
GUID-345B36A6-B5FB-46DD-B5AE-81A1599FFC6E v1
Apply the same measures as in the case with a single set of setting parameters. This
means that an underreaching zone must not overreach the end of a protected circuit
for the single phase-to-earth faults.
Set the values of the corresponding zone (zero-sequence resistance and reactance)
equal to:
1MRK 505 393-UEN B
Section 7
Impedance protection
Line differential protection RED650 2.2 IEC 125
Application manual