ABB Relion 670 series - Load Impedance Limitation, Without Load Encroachment Function330

The final reach in resistive direction for phase-to-ground fault loop measurement
automatically follows the values of the line-positive and zero-sequence resistance, and at
the end of the protected zone is equal to equation 139.
( )
1
R 2 R1 R0 RFPG
3
= × + +
ANSIEQUATION2303 V1 EN (Equation 261)
2X1Zx X0Zx
arctan
2 R1Zx R0Zx
loop










EQUATION2304 V2 EN (Equation 262)
Setting of the resistive reach for the underreaching zone 1 should follow the condition to
minimize the risk for overreaching:
RFPG 4.5 X1£ ×
ANSIEQUATION2305 V1 EN (Equation 263)
The fault resistance for phase-to-phase faults is normally quite low, compared to the fault
resistance for phase-to-ground faults. To minimize the risk for overreaching, limit the
setting of the zone1 reach in resistive direction for phase-to-phase loop measurement in
the phase domain to:
61
R
FPPZx X Zx


IECEQUATION2306 V3 EN (Equation 264)
8.9.3.7 Load impedance limitation, without load encroachment function
The following instructions are valid when Phase selection with load enchroachment,
quadrilateral characteristic function FRPSPDIS (21) is not activated. To deactivate the
function, the setting of the load resistance RLdFwd and RLdRev in FRPSPDIS (21) must
be set to max value (3000). If FRPSPDIS (21) is to be used for all or some of the measuring
zones, the load limitation for those zones according to this chapter can be omitted. Check
the maximum permissible resistive reach for any zone to ensure that there is a sufficient
setting margin between the boundary and the minimum load impedance. The minimum
load impedance (Ω/phase) is calculated as:
Section 8 1MRK 506 369-UUS -
Impedance protection
330 Line distance protection REL670 2.2 ANSI
Application manual