ABB RELION RER670, Applications Manual

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Substation A
Substation B
Z
lineAB,1
(pos. seq)
Z
lineAB,0
(zero seq)
Z
lineBC,1
(pos. seq)
Z
lineBC,0
(zero seq)
U
0A
U
0B
2I
0
Phase to earth fault
R
N
Z
T,1
(pos. seq)
Z
T,0
(zero seq)
Source impedance
Z
sc
(pos. seq)
IEC16000126-1-en.vsdx
IEC16000126 V1 EN-US
Figure 58: Equivalent of power system for calculation of setting
The residual fault current can be written:
0
1 0
2
2
2 2
phase
f
U
I
Z Z R

   
IECEQUATION16034 V1 EN-US
(Equation 47)
Where
U
phase
is the phase voltage in the fault point before the fault
Z
1
is the total positive sequence impedance to the fault point. Z
1
= Z
sc
+Z
T,1
+Z
lineAB,1
+Z
lineBC,1
Z
0
is the total zero sequence impedance to the fault point. Z
0
= Z
T,0
+2R
N
+Z
lineAB,0
+Z
lineBC,0
R
f
is the fault resistance.
The residual voltages in stations A and B can be written:
 
0 0 ,0
2 2
A T N
U I Z R
  
IECEQUATION16097 V1 EN-US
(Equation 48)
 
0 0 ,0 ,0
2 2
B T N lineAB
U I Z R Z
   
IECEQUATION16098 V1 EN-US
(Equation 49)
Section 8
1MRK 506 375-UEN A
Current protection
178 Railway application RER670 2.2 IEC
Application manual