Why are power lines buzzing

High-voltage power lines: why do they hum when wet?

In the countryside or in quiet areas, there is a strange hum near power lines in wet weather. Many a contemporary who lives near high-voltage lines can be terribly annoyed by the humming noises of damp high-voltage lines. The cause is vibrating water droplets on the pipes.

Water has more "swing"

Power lines have a frequency of 50 Hertz. So they swing once every fiftieth of a second. Water droplets that form on the lines during rain, fog or snowfall, on the other hand, vibrate at a frequency of 100 Hertz, i.e. twice within a fiftieth of a second. And as they vibrate, they change shape.

Visible hum

A large drop of water is elongated twice during a period of oscillation and then returns to its original spherical shape. This process creates the unpleasant hum. Swiss researchers have made this phenomenon visible. They sprayed water on a live pipe and filmed it with a high-speed camera.

A coating can help

The researchers' experiments also showed that the fewer drops there are on the pipe and the more evenly the water is distributed on the pipe, the quieter the hum. Since it is the swaying drops of water that cause the hum, research has begun on new coatings for high-voltage lines. They should prevent the formation of drops on the lines as far as possible or accelerate the drying process.