Meshed Network Without Parallel Line - ABB Relion 670 Series Applications Manual

Section 7
Current protection
This protection function must operate only in a selective way. So check all system and transient
conditions that could cause its unwanted operation.
Only detailed network studies can determine the operating conditions under which the highest
possible fault current is expected on the line. In most cases, this current appears during three-
phase fault conditions. But also examine single-phase-to-ground and two-phase-to-ground
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.
GlobalBaseSel : Selects the global base value group used by the function to define ( IBase ), ( VBase )
and ( SBase ).
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
operation. Normally this parameter is set to
protection is to be used mainly for multi phase faults,
Pickup : Set operate current in % of IBase .
MultPU : The operate current can be changed by activation of the binary input MULTPU to the set
MultPU .
factor
IP>>MinEd2Set : Minimum settable operate phase current level in % of IBase, for IEC 61850 Ed. 2
settings.
IP>>MaxEd2Set : Maximum settable operate phase current level in % of IBase, for IEC 61850 Ed. 2
settings.
7.1.3.1

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 51, apply a fault in B and then calculate the
current through-fault phase current I
impedance values for Z
maximum through fault current from A to B.
120
1 out of 3 and will thus detect all fault types. If the
. The calculation should be done using the minimum source
fB
and the maximum source impedance values for Z
A
2 out of 3 should be chosen.
in order to get the
B
1MRK 511 358-UUS A
Pickup for
M12915-9 v7
Application manual