ABB RELION REX640 Technical Manual page 905

1MRS759142 C
REX640
Technical Manual
Phase-to-earth
X
(2· Z + Z )/3 + Z
1source 0source
GUID-E54983FE-9918-4B5A-A14F-67727209EAFC V2 EN
Figure 491: Tripping characteristic in case the zone characteristic is "Mho
(circular)" and Pol quantity zone is "Cross pol"
In case of positive-sequence polarization "Pos. seq. volt.", the polarization voltage is
the positive-sequence voltage. The voltage phase angle is rotated to match the original
fault loop voltage. The positive-sequence polarization expands the tripping
characteristic according to the prevailing system conditions. In case of short circuit
faults, the circle expands as a function of the source impedance magnitude Z
In case of an earth fault, the circle expands as a function of source impedance and
earthing impedance magnitudes: (Z
Phase-to-earth
X
( Z + Z )/3 + Z
1source 0source
GUID-427F3CC6-5BF9-4D7A-8B8F-F5F2C6A4E096 V2 EN
Figure 492: Tripping characteristic in case the zone characteristic is "Mho
(circular)" and Pol quantity zone is "Pos. seq. volt."
(2· Z + Z )/3
1Line 0Line
R
E
+ Z )/3 + Z
1source 0source
Phase-to-phase/three-phase
(2· Z + Z )/3
1Line 0Line
R
Section 4
Protection functions
Phase-to-phase
X
Z
1source
1source
.
E
X
Z /2
1source
Z
1Line
R
/2.
Z
1Line
R
899