8.5.3.8
Load impedance limitation, with load encroachment function activated
SEMOD154704-129 v1
The parameters for load encroachment shaping of the characteristic are found in the
description of the phase selection with load encroachment function, section
reach with load encroachment characteristic"
. If the characteristic for the impedance
measurement shall be shaped with the load encroachment algorithm, the parameter
OperationLdCmp
in the phase selection has to be switched
On
.
8.5.3.9
Setting of minimum operating currents
SEMOD154704-132 v2
The operation of the distance function will be blocked if the magnitude of the currents
is below the set value of the parameter
IMinOpPE
.
The default setting of
IMinOpPE
is 20% of
IBase
where
IBase
is the chosen base
current for the analogue input channels. The value have been proven in practice to be
suitable in most of the applications. However, there might be applications where it is
necessary to increase the sensitivity by reducing the minimum operating current down
to 10% of the IED base current. This happens especially in cases, when the IED serves
as a remote back-up protection on series of very long transmission lines.
If the load current compensation is activated, there is an additional criteria
IMinOpIN
that will block the phase-ground loop if the 3I0<
IMinOpIN
. The default setting of
IMinOpIN
is 5% of the IED base current
IBase
.
The minimum operating fault current is automatically reduced to 75% of its set value,
if the distance protection zone has been set for the operation in reverse direction.
8.5.3.10
Setting of timers for distance protection zones
SEMOD154704-138 v1
The required time delays for different distance-protection zones are independent of
each other. Distance protection zone1 can also have a time delay, if so required for
selectivity reasons. One can set the time delays for all zones (basic and optional) in a
range of 0 to 60 seconds. The tripping function of each particular zone can be inhibited
by setting the corresponding
Operation
parameter to
Off
. Different time delays are
possible for the ph-E (
tPE
) measuring loops in each distance protection zone
separately, to further increase the total flexibility of a distance protection.
8.6
Additional distance protection directional function for
earth faults ZDARDIR
SEMOD175630-1 v3
Section 8
1MRK 504 163-UUS A
Impedance protection
312
Transformer protection RET670 2.2 ANSI
Application manual
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