ABB RET670 - Page 403

IBase: Base current in primary A. This current is used as reference for current setting.
If possible to find a suitable value the rated current of the protected object is chosen.
OpModeSel: This parameter can be set to 2 out of 3 or 1 out of 3. The setting controls
the minimum number of phase currents that must be larger than the set operate current
Pickup for operation. Normally this parameter is set to 1 out of 3and will thus detect all
fault types. If the protection is to be used mainly for multi phase faults, 2 out of 3
should be chosen.
Pickup: Set operate current in % of IBase.
MultPU: The operate current can be changed by activation of the binary input
MULTPU to the set factor MultPU.
Meshed network without parallel line
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
179, 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
Figure 179: 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 180. 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.
1MRK504116-UUS C Section 3
IED application
397
Application manual