Hitachi Relion 670 Series Applications Manual page 167

1MRK506375-UEN Rev. N
Phase to earth fault
IEC16000126 V1 EN-US
Figure 64:
The residual fault current can be written:

2 I
0
2
IECEQUATION16034 V1 EN-US
Where
U is the phase voltage in the fault point before the fault
phase
Z is the total positive sequence impedance to the fault point. Z
1
Z is the total zero sequence impedance to the fault point. Z
0
R is the fault resistance.
f
The residual voltages in stations A and B can be written:

U 2
0 A
IECEQUATION16097 V1 EN-US

U 2
0 B
IECEQUATION16098 V1 EN-US
The residual power, measured by the sensitive earth fault protections in A and B will be:

S 2
0 A
IECEQUATION16099 V1 EN-US
Railway application RER670
Application manual
Source impedance
Z (pos. seq)
sc
Z (pos. seq)
T,1
R
Z (zero seq)
T,0
U
0A
2I
0
Z
lineAB,1
Z
lineAB,0
U
0B
Z
lineBC,1
Z
lineBC,0
IEC16000126-1-en.vsdx
Equivalent of power system for calculation of setting
2 U
phase
   
Z Z 2 R
1 0 f
 
 
I Z 2 R
0 T ,0 N

  
I Z 2 R Z
0 T ,0 N lineAB

U 2 I
0 A 0
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N
Substation A
(pos. seq)
(zero seq)
Substation B
(pos. seq)
(zero seq)
= Z
0

,0
= Z +Z +Z +Z
1 sc T,1 lineAB,1 lineBC,1
+2R +Z +Z
T,0 N lineAB,0 lineBC,0
Section 8
Current protection
(Equation 48)
(Equation 49)
(Equation 50)
(Equation 51)
161