Fuji Electric EW32EAG - Page 106

104
6
Short-circuit current calculation
6-1 Calculating short-circuit current
6-1-4 Impedance examples
Table 6-1 Transformer impedance examples
Transformer
capacity (kVA)
3-phase transformer
6.3kV/210V
Oil immersed self-cooling
6.3kV/210V
Cast-resin
20kV/420V
Oil immersed self-cooling
20kV/420V
Cast-resin
Impedance (%) Impedance (%) Impedance (%) Impedance (%)
Z
T RT XT ZT RT XT ZT RT XT ZT RT XT
3
5
7.5
10
15
20 2.3 2.1 0.9 3.0
30 2.2 1.9 1.1 4.7 2.27 4.12
50 2.1 1.8 1.1 4.7 1.94 4.28
75 2.4 1.6 1.8 4.4 1.56 4.11
100 2.4 1.6 1.8 4.5 1.5 4.24
150 2.4 1.6 1.8 4.2 1.29 4.0
200 2.5 1.5 2.0 4.5 1.17 4.35
300 2.6 1.4 2.2 4.5 1.2 4.33
500 3.0 1.3 2.7 4.8 0.8 4.69 5.0 1.56 4.76 6.0 1.0 5.92
750 5.3 1.5 5.1 6.0 0.8 5.95 5.0 1.40 4.80 6.0 0.9 5.93
1000 5.1 1.4 4.9 7.0 0.4 6.96 5.0 1.26 4.84 6.0 0.8 5.95
1500 5.6 1.3 5.4 7.0 0.6 6.97 5.0 1.2 5.37 7.0 0.75 6.96
2000 6.3 1.3 6.2 7.5 0.65 7.47 5.0 1.1 5.39 7.0 0.7 6.96
Table 6-2 Impedance of rubber and plastic-sheathed cables
Impedance of 600V, 3-core (CV, EV, PV, VV) round stranded cable at 50Hz
Nominal conductor
cross section
(mm
2
)
CV cable EV cable
R (90°C)
(:/km)
X
L
(:/km)
Z
(:/km)
R (75°C)
(:/km)
XL
(:/km)
Z
(:/km)
2.0 12.5 0.0992 12.5 11.9 0.0992 11.9
3.5 6.78 0.0914 6.78 6.64 0.0914 6.64
5.5 4.51 0.0914 4.51 4.31 0.0914 4.31
8 3.14 0.0870 3.14 2.99 0.0870 2.99
14 1.76 0.0811 1.76 1.58 0.0811 1.58
22 1.10 0.0804 1.10 1.05 0.0804 1.05
38 0.653 0.0761 0.657 0.623 0.0761 0.628
60 0.408 0.0757 0.415 0.388 0.0757 0.395
100 0.242 0.0761 0.254 0.231 0.0751 0.243
150 0.159 0.0732 0.175 0.152 0.0732 0.169
200 0.126 0.0745 0.146 0.121 0.0745 0.142
250 0.100 0.0729 0.124 0.0962 0.0729 0.121
325 0.0808 0.0714 0.108 0.0775 0.0714 0.105
CV: Cross-linked polyethylene insulated power cable with vinyl sheath
EV: Polyethylene insulated power cable with vinyl sheath
PV: Ethylene propylene rubber insulated power cable with vinyl sheath
VV: Vinyl insulated power cable with vinyl sheath