MODULE 2 — Transmission Line Components
2.1 Main Components of Overhead Lines
Hover
Components:
- ■ Conductors (ACSR/AAC)
- ■ Earthwire (Ground)
- ■ Insulators (Disc/Strain)
- ■ Lattice Steel Structure
2.2 Types of Conductors
$$ N_{strands} = 3n^2 - 3n + 1 $$
$$ D_{total} = (2n-1) \times d_{strand} $$
Where $n$ is number of layers.
n=3 | Strands=19
| ACSR Typical
2.10 String Efficiency
$$ K = \frac{C_{self}}{C_{mutual}} $$
$$ V_1 = \frac{V}{3 + 4K + K^2} $$
$$ \eta = \frac{V_{total}}{n \times V_n} \times 100\% $$
η = 86.0%
2.11 Corona & Critical Voltage
Critical Disruptive Voltage
$$ V_d = m_0 \delta r \cdot E_0 \ln\left(\frac{d}{r}\right)
$$
Peek's Corona Loss Formula
$$ P_c = \frac{241}{\delta}(f + 25)\sqrt{\frac{r}{d}}(V -
V_d)^2 \times 10^{-5} $$
V < Vd: No Corona
Loss
2.12 Sag Calculation & Clearances
Basic Sag
$$ S = \frac{w \cdot l^2}{8T} $$
With Wind & Ice
$$ S = \frac{w_{total} \cdot l^2}{8T} \quad (w_{total}
= \sqrt{(w+w_{ice})^2 + w_w^2}) $$
Sag = 2.50 m