Resistance, inductance, capacitance and conductance characterise lines.
Series resistance R and inductive reactance X=ωL, shunt capacitance C and leakage conductance G. Geometry (spacing, conductor radius, bundling) sets L and C: L≈2×10⁻⁷ln(D/r′) H/m. Short, medium (π) and long line models are chosen by length.
A 400 kV line has X≈0.3 Ω/km.
Line parameters decide how power flows, how voltage drops and how much charging current a line draws, so they must be known for planning.
Resistance, inductance, capacitance and conductance characterise lines.
Line parameters decide how power flows, how voltage drops and how much charging current a line draws, so they must be known for planning.
The conductors and the earth form a capacitor over long distances, and the charging current becomes significant for long lines.
The characteristic impedance of a lossless line, which is the ratio of voltage to current for a travelling wave.
Typical applications include calculating the voltage drop along a 30 km distribution line, estimating the charging current of an underground cable and choosing conductor spacing to reduce inductance on a transmission line.
Study "Per-unit system" first (topic 68 of 106 in Electrical Engineering). It covers the groundwork this topic builds on.
Skin effect raises R. Bundled conductors reduce corona. Transposition balances phases.
A 400 kV line has X≈0.3 Ω/km.
The next topic is "Distribution systems", which builds directly on this one.
It is classed as Intermediate in Electrical Engineering (topic 69 of 106). It is an intermediate topic. Work through the beginner topics in Electrical Engineering first.
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