ABB rec670 - Meshed Network Without Parallel Line

MultPU: The set operate current can be changed by activation of the binary input
MULTPU
to the set factor MultPU.
8.1.3.1 Meshed network without parallel line
M12915-9 v8
The following fault calculations have to be done for three-phase, single-phase-to-
ground and two-phase-to-ground faults. With reference to Figure
55, apply a fault in B
and then calculate the current through-fault phase current I
fB
. The calculation should be
done using the minimum source impedance values for Z
A
and the maximum source
impedance values for Z
B
in order to get the maximum through fault current from A to
B.
~
~
Z
A
Z
B
Z
L
A B
IED
I
fB
Fault
ANSI09000022-1-en.vsd
ANSI09000022 V1 EN-US
Figure 55: Through fault current from A to B: I
fB
Then a fault in A has to be applied and the through fault current I
fA
has to be
calculated, Figure
56. In order to get the maximum through fault current, the minimum
value for Z
B
and the maximum value for Z
A
have to be considered.
1MRK 511 401-UUS A Section 8
Current protection
Bay control REC670 2.2 ANSI 149
Application manual