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
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
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
Section 8 1MRK 506 369-UUS -
Impedance protection
300 Line distance protection REL670 2.2 ANSI
Application manual
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