ABB Relion 650 Series Technical Manual page 139

1MRK 506 326-UUS B
ANSI05000722 V1 EN-US
Figure 75: Setting angles for discrimination of forward and reverse fault for quadrilateral
The reverse directional characteristic is equal to the forward characteristic rotated by 180
degrees.
ZDNRDIR (21D) gives binary coded directional information per measuring loop on the output
STDIRCND.
The polarizing voltage is available as long as the positive-sequence voltage exceeds 5% of the set
base voltage
close-in faults.
For close-in three-phase faults, the V1AM memory voltage, based on the same positive sequence
voltage, ensures correct directional discrimination.
The memory voltage is used for 100ms or until the positive sequence voltage is restored. After
100ms, the following occurs:
• If the current is still above the set value of the minimum operating current (between 10% and
30% of
•
•
• If the current decreases below the minimum operating value, the memory resets and no
directional indications will be given until the positive sequence voltage exceeds 10% of its
rated value.
Line distance protection REL650
Technical manual
X
AngNegRes
characteristic
VBase . So the directional element can use it for all unsymmetrical faults including
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.
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AngDir
R
en05000722_ansi.vsd
Section 5
Impedance protection
133