Noise from Greek High Voltage Distribution Box

The humming or buzzing noise from high-voltage distribution boxes is primarily caused by transformer vibrations and corona discharge, influenced by electrical, mechanical, and environmental factors.

Transformer-Related Noise

Transformers inside distribution boxes are a major source of audible noise. This occurs due to magnetostriction, a property of the core material that causes it to expand and contract as the magnetic field changes, producing vibrations at twice the power frequency (around 100 Hz) and its harmonics, which are audible to humans . Additional noise arises from winding vibrations, cooling systems (fans or oil pumps), and structural resonance, where vibrations are amplified by the transformer's frame or mounting . Noise intensity increases with higher load currents and voltage harmonics.

Corona Discharge Noise

High-voltage conductors can produce a hissing or buzzing sound due to corona discharge, which occurs when the electric field around the conductor exceeds the breakdown strength of the surrounding air . This discharge ionizes the air, generating audible noise, faint visible glow, and minor energy loss known as corona loss. Environmental conditions such as humidity, rain, fog, and air density can intensify this noise, making it louder on humid or wet days . Sharp points, surface contamination, or weathering on conductors can also increase corona activity.

Electromagnetic Interference

High-voltage equipment generates electromagnetic fields (EMF) that can induce additional noise in nearby electronic devices or communication lines. While this is usually not audible, it can contribute to the overall perception of buzzing or humming in the vicinity of the distribution box .

Mitigation Strategies

Reducing noise involves addressing both mechanical and electrical sources:

• Transformer design improvements: Using high-grade, low-magnetostriction silicon steel, optimized core laminations, and proper winding support reduces vibrations .
• Structural damping: Reinforcing foundations and using vibration-absorbing mounts can minimize resonance.
• Corona control: Bundled conductors, smooth surfaces, and regular maintenance reduce corona discharge and associated noise .
• Environmental considerations: Installing barriers or acoustic enclosures can help mitigate noise propagation in populated areas. Understanding these factors explains why high-voltage distribution boxes in Greece or elsewhere may emit noticeable humming or buzzing sounds, especially under high load or humid conditions. Proper design, maintenance, and environmental management are key to minimizing the noise impact.