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1MRK 502 071-UUS A
9.1.3.2
Generator protection REG670 2.2 ANSI and Injection equipment REX060, REX061, REX062
Application manual
I
F
A
Z
~
A
IED
ANSI09000024 V1 EN-US
Figure 170:
Fault current: I
The IED setting value Pickup is given in percentage of the primary base current value,
IBase. The value for Pickup is given from this formula:
Is
=
Pickup
IBase
ANSIEQUATION1147 V1 EN-US
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 171, where the
two lines are connected to 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
maximal influence from the parallel line for the IED in Figure
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
on the healthy line (this applies for single-phase-to-ground and two-phase-to-ground
faults) is calculated.
Z
L
Fault
F
×
100
and I
fA
Section 9
Current protection
B
Z
~
B
ANSI09000024-1-en.vsd
mentioned previously. The
fB
171
will be with a fault
(Equation 170)
M12915-34 v7
)
M
345
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