ABB REL650 Applications Manual page 54

Section 3
REL650 setting examples
48
X
20
Line impedance
15
85 % of Line impedance
10
5
5 10
IEC09000410 V1 EN
Figure 7: Line impedance diagram
The setting Z1is calculated as:
= ×
Z 1 0.85 Z
Line posseq ,
GUID-B193DA37-6B3E-480E-80EE-0300427E4382 V1 EN
4. Set MhoCharZ1 to Directional.
This setting will be used if CharPGZ1 and CharPPZ1 is set to Mho.
If CharPGZ1 or CharPPZ1 is set as Mho then only Z1 setting will be
used. RFPG1 and RFPP1 will not have any effect.
5. If CharPPZ1 is selected as Quadrilateral then set RFPP1 to 15 Ω
The fault resistance setting for phase-to-phase faults is normally the resistance arc
between the faulty phases. The fault resistance can approximately be calculated by
using the van Warrington expression:
28700
» ×
R L
arc
1 4 .
I
GUID-F2E73133-F8B8-4594-BB6D-D9823E83F0E4 V1 EN
where:
• I is the arc current in A
• L is the length of the arc in m
The length of the arc is equal to the distance between the phases. For this line the
distance between the phases is 5 m.
The fault current for a phase-to-phase fault at the open line end and minimum short
circuit capacity is:
R
15
IEC09000410_1_en.vsd
= × + = W
0.85 2.5 j 17.5 15.0
1MRK 506 334-UUS A
(Equation 5)
(Equation 6)
Application manual