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R
X
ArgDir
ArgNegRes
en05000722.vsd
IEC05000722 V1 EN-US
Figure 135: Setting angles for discrimination of forward and reverse fault in Directional
impedance quadrilateral function ZDRDIR
The reverse directional characteristic is equal to the forward characteristic rotated by 180
degrees.
The polarizing voltage is available as long as the positive sequence voltage exceeds 5% of the
set base voltage
UBase. So the directional element can use it for all unsymmetrical faults
including close-in faults.
For close-in three-phase faults, the U1
L1M
memory voltage, based on the same positive
sequence voltage, ensures correct directional discrimination.
The memory voltage is used for 100 ms or until the positive sequence voltage is restored.
After 100 ms the following occurs:
•
If the current is still above the set value of the minimum operating current (between 10
and 30% of the set IED rated current
IBase), the condition seals in.
•
If the fault has caused tripping, the trip endures.
•
If the fault was detected in the reverse direction, the measuring element in the
reverse direction remains in operation.
•
If the current decreases below the minimum operating value, the memory resets until the
positive sequence voltage exceeds 10% of its rated value.
7.3.3.11
Setting of timers for distance protection zones
SEMOD55087-147 v6
The required time delays for different distance protection zones are independent of each
other . Distance protection zone 1 can also have a time delay, if so required for selectivity
reasons. Time delays for all zones can be set 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 phase-to-earthtPE and for the
phase-to-phase
tPP measuring loops in each distance protection zone separately, to further
increase the total flexibility of a distance protection.
Section 7
1MRK 505 343-UEN B
Impedance protection
218
Application manual
Содержание Relion 670 series
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