Alstom MiCOM P546 - 6.7.5 Calculation of full line impedance (full 100 kms); 6.7.6 Calculation of total impedance till remote bus bar; 6.7.7 Calculation of through fault X;R; 6.7.8 Calculation of through fault If

P54x/EN AP/La4 Application Notes
(AP) 6-86 MiCOM P543, P544, P545 & P546
AP
6.7.5 Calculation of full line impedance (full 100 kms)
Z1 = 0.089 + j 0.476 ohm / km
ZL = 8.9 + j 47.6 ohms
ZL = 48.42 ohms with an angle 79.4 deg
6.7.6 Calculation of total impedance till remote bus bar
ZT = Zs
+ ZL = 8.988 + j 50.917 ohms
= 51.7 ohms with an angle of 80 deg
6.7.7 Calculation of through fault X/R
X/R thro
= 50.917 / 8.988
= 5.66
6.7.8 Calculation of through fault If
If thro
= 230kV / (1.732 * 51.7 )
= 2568.5 A primary
= 2.14 A (secondary)
6.7.9 Calculation of line impedance till Zone1 reach point (80kms)
Zzon
e1 = 0.8 * ZL = 7.12 + j 38.08 ohms
= 38.73 ohms with an angle of 79.4 deg
6.7.10 Calculation of total impedance till Zone1 reach point
ZTzo
ne1 = Zs + Zzone1
= 7.208 + j 41.397 ohms
= 42.019 ohms with an angle of 80 deg
6.7.11 Calculation of X/R till Zone1 reach point
X/R zone
1 = 41.397 / 7.208
= 5.74
6.7.12 Calculation of fault current till Zone1 reach point
If zone1 = 230 kV / (1.732 * 42.019)
= 3160.34 A (primary) = 2.63 A (secondary)