Why do High-Voltage Transmission Lines produce a Hissing Sound?
The hissing or crackling noise around high-voltage transmission lines is primarily caused by corona discharge.
Corona occurs when the electric field intensity around an energized conductor exceeds the critical value required to ionize the surrounding air. This partial electrical discharge produces audible noise, often more noticeable during humid, rainy, or wet weather.
Key Technical Factors:
- High electric field intensity around conductors.
- Conductor surface irregularities and sharp edges.
- Atmospheric conditions, particularly moisture and rain.
- Conductor diameter, spacing, and operating voltage.
Corona discharge can also cause radio interference, ozone generation, and additional power losses. Its effects can be minimized through proper conductor design, bundled conductors, and corona rings at suitable high-voltage equipment terminals.