ABB Relion 670 series - Page 449

ß
ANSI11000300_1_en.vsd
1 2Vcomp VAB IAB Z FW= - ×
2 2Vcomp VAB IAB Z REV= + ×
IAB jX×
2IAB Z REV- ×
IAB jX×
2IAB Z FW×
ANSI11000300 V1 EN-US
Figure 242: Simplified offset mho characteristics for A-to-B fault in zone 2
Operation occurs if 90° ≤ β ≤ 270°.
Impedance defined in the Figure
241 and 242 is described in equation 118.
2 2 Z Fwd Z Fwd ImpedanceAng= Ð
2 2 Z R Z Rev ImpedanceAngev = Ð
GUID-007D6357-B7CF-4C21-B772-2245F06C83A2 V2 EN-US (Equation 118)
Voltage and current phasors selected for different measuring loops:
Phase Phase:
Sl.No Measuring Loop Voltage Phasor Current Phasor
1
A-B
VAB
IAB
2
B-C
VBC
IBC
3
C-A
VCA
ICA
Enhanced Reach:
1MRK 502 066-UUS B Section 7
Impedance protection
443
Technical manual