ABB 615 Series - Page 382

~
~
~
AB C
Uo   
E
A
E
B
E
C
Io
Reverse
Fault
Y
Fd
L
cc
R
cc
Y
Bg
I
eFd
(I
eTot
‐ I
eFd
)   
R
n
Protectedfeeder  
Background network
Im(Yo)
Re(Y
o)
Reverse fault:
Y
o≈‐j*I
eFd
/U
ph
VG
Vph
IG
GUID-2C307D73-EF4A-479A-A6E5-47CAC730188C V1 EN
Figure 176: Admittance calculation during a reverse fault
R
CC
Resistance of the parallel resistor
L
CC
Inductance of the compensation coil
R
n
Resistance of the neutral grounding resistor
Y
Fd
Phase-to-ground admittance of the protected feeder
Y
Bg
Phase-to-ground admittance of the background network
For example, in a 15 kV compensated network with the magnitude of the ground-fault
current in the protected feeder being 10 A (Rf = 0 Ω), the theoretical value for the
measured admittance during a ground fault in the reverse direction, that is, outside the
protected feeder, can be calculated.
Section 4 1MAC059074-MB A
Protection functions
376 615 series ANSI
Technical Manual