ABB RELION RET670 - Load Impedance Limitation, Without Load Encroachment Function

Set separately the expected fault resistance for the phase-to-ground faults (RFPE) for
each zone. Set all remaining reach setting parameters independently of each other for
each distance zone.
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 185.
R
1
3
---
2 R1PE× R0PE+
( )
RFPE+=
EQUATION567 V1 EN-US (Equation 185)
2 X1PE +X0
arctan
2 R1PE +R0
loop
j
é ù
×
ê ú
=
×
ê ú
ë û
EQUATION1457 V1 EN-US (Equation 186)
Setting of the resistive reach for the underreaching zone1 should follow the condition:
4.5 1RFPE X£ ×
EQUATION569 V2 EN-US (Equation 187)
8.5.3.7 Load impedance limitation, without load encroachment function
SEMOD154704-91 v2
The following instructions is valid when the load encroachment function is not
activated (OperationLdCmp is set to Off). If the load encroachment function 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 IED
boundary and the minimum load impedance. The minimum load impedance (Ω/phase)
is calculated as:
2
minload
V
Z
S
=
EQUATION1780-ANSI V1 EN-US (Equation 188)
Where:
V is the minimum phase-to-phase voltage in kV
S is the maximum apparent power in MVA.
Section 8 1MRK 504 163-UUS A
Impedance protection
310 Transformer protection RET670 2.2 ANSI
Application manual