Meshed Network With Parallel Line - ABB Relion 670 Series Applications Manual

Section 7
Current protection
The protection function can be used for the specific application only if this setting value is equal
to or less than the maximum fault current that the IED has to clear, I
~
ANSI09000024 V1 EN-US
Figure 53: Fault current: I
The IED setting value
value for
Pickup
ANSIEQUATION1147 V1 EN-US
7.1.3.2

Meshed network with parallel line

In case of parallel lines, the influence of the induced current from the parallel line to the protected
line has to be considered. One example is given in figure
the same busbars. In this case the influence of the induced fault current from the faulty line (line 1)
to the healthy line (line 2) is considered together with the two through fault currents I
mentioned previously. The maximal influence from the parallel line for the IED in figure
with a fault at the C point with the C breaker open.
A fault in C has to be applied, and then the maximum current seen from the IED (I
line (this applies for single-phase-to-ground and two-phase-to-ground faults) is calculated.
122
I
F
A
Z
A
IED
F
Pickup is given in percentage of the primary base current value, IBase . The
Pickup is given from this formula:
Is
= ×
100
IBase
B
Z Z
L B
Fault
54
in figure 53.
F
~
ANSI09000024-1-en.vsd
where the two lines are connected to
) on the healthy
M
Application manual
1MRK 511 358-UUS A
(Equation 24)
M12915-34 v6
and I
fA fB
54 will be