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The topmost conductor in hv transmission line is
phase conductor
Y-phase conductor
R-phase conductor
Earth conductor
Earth conductor
In high voltage (HV) transmission lines, the topmost conductor is the ground wire (or earth wire), which is placed above the phase conductors. Its primary purpose is to provide electrostatic shielding against direct lightning strikes to the line conductors.
In high voltage (HV) transmission lines, the topmost conductor is the ground wire (or earth wire), which is placed above the phase conductors. Its primary purpose is to provide electrostatic shielding against direct lightning strikes to the line conductors.
ZsтАЛ=CLтАЛтАЛ тАФ Surge impedance of a transmission line
P=ZsтАЛV2тАЛ тАФ Surge Impedance Loading (SIL)
The earth wire acts as a Faraday cage or a shield. During a lightning strike, the earth wire intercepts the lightning stroke, providing a low-impedance path to the ground through the steel towers, thereby preventing surge voltages from reaching the phase conductors.
The earth wire is connected to the transmission tower, which is directly grounded.
It provides a protection angle (shielding angle) to ensure phase wires remain within the protected zone.
The earth wire is typically made of galvanized steel for high mechanical strength.
It helps in reducing the intensity of induced voltages on phase lines during lightning discharges.
Prevents direct lightning strikes on phase conductors
Reduces the magnitude of surge voltages reaching substations
Provides a low impedance path for fault currents
Increases tower structural weight and cost
Requires proper earthing resistance to be effective
EHV and UHV transmission lines
Overhead distribution lines in lightning-prone areas
The shield angle is typically kept between 20┬░ to 30┬░ to provide optimal protection.
Option A, B, and C refer to the phase conductors which are always placed below the earth wire to minimize the risk of direct lightning hits.
D is correct тАФ The topmost conductor in a transmission line is the earth wire, designed to intercept lightning strikes.
Always remember that the ground wire is placed at the highest point to ensure it catches lightning before the current reaches the power-carrying phase conductors.