ABB RES670 Technical Manual page 188

Section 8
Current protection
182
For close-in three-phase faults, the V1
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 (7% of
the set terminal 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.
The directional setting is given as a characteristic angle AngleRCA for the function and
an angle window ROADir.
memory voltage, based on the same positive
AM
Phasor measurement unit RES670 2.2 ANSI
1MRK 511 408-UUS A
Technical manual