Setting Of Zones For Parallel Line Application - ABB REG670 Applications Manual

Section 8
Impedance protection
8.3.4.6
254
Reverse zone
The reverse zone that is normally used in the communication schemes for functions
like fault current reversal logic, weak-in-feed logic or issuing carrier send in blocking
scheme must detect all faults in the reverse direction which is detected in the opposite
IED by the overreaching zone 2. The maximum reach for the protection in the opposite
IED can be achieved with the series capacitor in operation.
The reactive reach can be set according to the following formula: X1=1.3·
(X1 -0.5(X1 -X ))
2Rem L C
Settings of the resistive reaches are according to the minimum load impedance:
Optional higher distance protection zones
When some additional distance protection zones (zone 4, for example) are used they
must be set according to the influence of the series capacitor.

Setting of zones for parallel line application

Parallel line in service – Setting of zone 1
With reference to section
of the 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-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 85.
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
X = X + X
0E 0 m0
EQUATION554 V1 EN
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:
Z 0
m
= -
K 0 1
× + +
2 Z 1 Z 0 R
f
EQUATION1426 V1 EN
Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062
"Parallel line applications", the zone reach can be set to 85%
1MRK 502 071-UEN -
(Equation 129)
(Equation 130)
(Equation 131)
Application manual