| |
|
|
|
magnetic field in µT at distance
from centreline |
|
0 m |
5 m |
10 m |
20 m |
|
400 kV
and
275 kV |
trough |
0.13 m spacing
0.3 m depth |
maximum |
83.30 |
7.01 |
1.82 |
0.46 |
|
typical |
20.83 |
1.75 |
0.46 |
0.12 |
|
direct
buried |
0.5 m spacing
0.9 m depth |
maximum |
96.17 |
13.05 |
3.58 |
0.92 |
|
typical |
24.06 |
3.26 |
0.90 |
0.23 |
|
Deep bore
tunnel |
0.4 m spacing
10-20 m depth |
maximum |
2.68 |
2.22 |
1.45 |
0.61 |
|
typical |
0.16 |
0.15 |
0.13 |
0.08 |
|
132 kV |
separate cores |
0.3 m spacing
1 m depth
|
typical |
9.62 |
1.31 |
0.36 |
0.09 |
|
single cable |
1 m depth |
typical |
5.01 |
1.78 |
0.94 |
0.47 |
|
33 kV |
single cable |
0.5 m depth |
typical |
1.00 |
0.29 |
0.15 |
0.07 |
|
11 kV |
single cable |
0.5 m depth |
typical |
0.75 |
0.22 |
0.11 |
0.06 |
|
400 V |
single cable |
0.5 m depth |
typical |
0.50 |
0.14 |
0.07 |
0.04 |
1. All fields calculated at 1 m above ground level
2. All fields are given to the same resolution for simplicity
of presentation (0.01 µT = 10 nT) but are not accurate to better
than a few percent.
3. Calculations at 132 kV and above ignore zero-sequence
current. This means values at larger distances are probably
underestimates, but this is unlikely to amount to more than
a few percent.
4. Cable designs are not standardised to the same extent
as overhead lines and the examples given here are representative.
