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2
Note: User should set the values of each section impedances into each Line_Element.
For the consideration of the section and their Line_Element, see section 2.32.5(i)
and section 2.32.6(iii).
For instance, the IED G makes calculation in the following sequences:
➢ At the outset, the IED G makes calculation of the equation (2.32-5) assuming that the fault
arises on line GJ.
➢ If the calculation result is not identical to the input data from a line, then the IED G makes
calculation with Equation (2.32-6) assuming that the fault arises on line JH.
➢ Then, the IED G makes calculation with Equation (2.32-7), when both Equation (2.32-5)
and Equation (2.32-6) do not hold true for the input data from a line, and finally the IED
G decides that the fault arises on line JS, as shown in Figure 2.32-2.
Equations by symmetrical components
In practice, the FL calculation is carried out in symmetrical components; hence, Equations
(2.32-4) to (2.32-7) are converted to symmetrical equations in the FL.
For example, in Figure 2.32-1, the distance ratio () can be expressed in symmetrical
components when we substitute symmetrical components† for Equation (2.32-4).
where,
V1G: Positive-sequence voltage at IED G
V1H: Positive-sequence voltage at IED H
I1H, I2H and I0H: Current (IH) at IED H represented by positive-sequence,
negative-sequence, and zero-sequence
I1d, I2d and I0d: Differential current (Id) represented by positive-sequence,
negative-sequence, and zero-sequence
Z11, Z12 and Z10‡ Line impedance (ZGH) represented by positive-sequence,
negative-sequence, and zero-sequence
†Note: When we can assume that the respective mutual-impedances are equal (Z
ab
=Z
bc
,
Z
bc
=Z
ca
, and Z
ca
=Z
ab
), symmetrical components (Z
11
, Z
12
and Z
10
) are obtained
from the following Equations (2.32-10) to (2.32-12):
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