ABB Relion 670 Series Applications Manual page 134

Section 8
Current protection
during three-phase fault conditions. But also examine single-phase-to-earth and two-phase-
to-earth conditions.
Also study transients that could cause a high increase of the line current for short times. A
typical example is a transmission line with a power transformer at the remote end, which can
cause high inrush current when connected to the network and can thus also cause the
operation of the built-in, instantaneous, overcurrent protection.
Common base IED values for primary current (
power (
GlobalBaseSel : This is used to select GBASVAL function for reference of base values.
Operation : Set the protection to On / Off .
OpMode : 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
operation. Normally this parameter is set to
protection is to be used mainly for multi phase faults,
IP>> : Set operate current in % of IB .
IP>>Max and IP>>Min should only be changed if remote setting of operation current level, IP>> ,
is used. The limits are used for decreasing the used range of the
outside
IP>>Max is smaller than IP>>Min , the limits are swapped.
StValMult : The set operate current can be changed by activation of the binary input ENMULT to
the set factor
8.1.3.1 Meshed network without parallel line
The following fault calculations have to be done for three-phase, single-phase-to-earth and
two-phase-to-earth faults. With reference to Figure 56, apply a fault in B and then calculate the
current through-fault phase current I
source impedance values for Z
get the maximum through fault current from A to B.
~
IEC09000022 V1 EN-US
Figure 56: Through fault current from A to B: I
Then a fault in A has to be applied and the through fault current I
Figure 57. In order to get the maximum through fault current, the minimum value for Z
the maximum value for Z
128
SBase ) are set in the global base values for settings function GBASVAL.
IP>>Max and IP>>Min , the closest of the limits to IP>> is used by the function. If
StValMult .
A
A
Z
A
IED
have to be considered.
A
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IBase ), primary voltage ( UBase ) and primary
1 out of 3 and will thus detect all fault types. If the
2 out of 3 should be chosen.
. The calculation should be done using the minimum
fB
and the maximum source impedance values for Z
I
fB
B
Z Z
L
Fault
fB
1MRK 511 401-UEN Rev. K
IP>> setting. If IP>> is set
~
B
IEC09000022-1-en.vsd
has to be calculated,
fA
Bay control REC670
Application manual
IP>> for
M12915-9 v8
in order to
B
and
B