ABB RELION REB500 Technical Manual page 50

Section 5
Bay protection functions
The settings
phase fault loops. The setting takes the ground fault resistance comprising the arc resistance
and the pylon footing resistance in relation to the line resistance into account.
Typical settings lie in the range RR(E)/X = 0.5...3.
The arc resistance RB can be calculated according to A.R. van C. Warrington as follows:

R
B
• d is the length of arc in m.
• I is the current in A.
• R
B
Since the unit is Ω/ph, the fault resistance appears differently in the impedance plane
according to the type of fault. Where the value of the fault resistance RF in Ω is known, it has
to be entered in the R/X diagram as follows:
phase-to-ground
fault:
phase-to-phase fault:
three-phase fault:
It is for this reason that fault resistance is compensated individually the parameters
RR . The parameter RR will generally be set lower than RRE , because the phase-to-phase fault
resistance is normally very low.
Phase to ground
IEC19000411 V1 EN-US
Figure 10: Faults with arc resistance
44
RRE and RR make provision for fault resistance in ground fault and phase-to-
28700 d
1.4
I
is the arc resistance in Ω.
R
F
Phase to phase
fault
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
R R / 1
F

R

R
R
R
F
Three phase
fault
18000009-IEC19000411-1-en.vsdx
1MRK 505 406-UEN B
 

k
0
R / 2
F
R / 3
F
R
F F
R
F
fault
Bay protection functions REB500
RRE and
Technical manual