Siemens 7PG2114 Application Manual page 36

⎛ ⎞
X
θ
= −
1
⎜ ⎟
Tan
⎝ ⎠
R
θ
=
87 o
θ
= =
cos 00544
R Z
S S
R = 0.07765 ohms/km (Primary)
L
R = 10 x 0.07765 = 0.7765Ω (Primary)
L
X = 0.28978 ohms/km
L
X = 10 x 0.28978 = j2.8978Ω (Primary)
L
Total impedance for a through fault at the remote busbar =
Z + Z = (R + R ) + (X + X
S L S L S
(0.0544 + 0.7765) + j(1.0876 +2.8978)
Z = 0.8309 + j3.9854 ohms
F
= 2 + 2
Z R X
= +
2
. 0 8309 . 3 9854
Z
Z = 4.071 ohms
F
Through Fault Current =
3
19.05x10
= =
I 4.68kA
F
4.071
Through fault current = 4.68kA compared to 17.5kA Busbar fault current due to the effect of the line impedance.
19.05kV
©2010 Siemens Protection Devices Limited
Ω =
X Z
&
S S
)
L
2
Zs
17.5kA
7PG2113/4/5/6 Solkor Applications Guide
θ
= Ω
sin . 1 0876
(Primary)
Z
L
4.68kA
Chapter 7 Page 36 of 49