page_title: Corona discharge
hierarchical_section_title: Corona discharge
caption_attribution_description: English: Corona discharge on corona ring of 500 kV overhead power line. The picture was taken at night by the Sony SLT-A37 camera on tripod, Sony DT 55-200/4-5.6 SAM lens @ 200mm/5.6, 90 seconds exposure via shutter release timer/intervalometer, ISO 200. Actually corona discharge looks a little weaker to the naked eye, but long exposure of camera does the job. Русский: Коронный разряд на защитном кольце (экране) высоковольтной воздушной линии электропередачи напряжением 500 кВ. ВЛ 500 кВ Белый Раст - Бескудниково
context_page_description: A corona discharge is an electrical discharge caused by the ionization of a fluid such as air surrounding a conductor carrying a high voltage. It represents a local region where the air has undergone electrical breakdown and become conductive, allowing charge to continuously leak off the conductor into the air. A corona occurs at locations where the strength of the electric field around a conductor exceeds the dielectric strength of the air. It is often seen as a bluish glow in the air adjacent to pointed metal conductors carrying high voltages, and emits light by the same property as a gas discharge lamp.
  In many high voltage applications, corona is an unwanted side effect. Corona discharge from high voltage electric power transmission lines constitutes an economically significant waste of energy for utilities. In high voltage equipment like cathode ray tube televisions, radio transmitters, X-ray machines, and particle accelerators, the current leakage caused by coronas can constitute an unwanted load on the circuit. In the air, coronas generate gases such as ozone and nitric oxide, and in turn, nitrogen dioxide, and thus nitric acid if water vapor is present.
context_section_description: A corona discharge is an electrical discharge caused by the ionization of a fluid such as air surrounding a conductor carrying a high voltage.  It represents a local region where the air (or other fluid) has undergone electrical breakdown and become conductive, allowing charge to continuously leak off the conductor into the air.   A corona occurs at locations where the strength of the electric field (potential gradient) around a conductor exceeds the dielectric strength of the air.  It is often seen as a bluish glow in the air adjacent to pointed metal conductors carrying high voltages, and emits light by the same property as a gas discharge lamp.
  In many high voltage applications, corona is an unwanted side effect. Corona discharge from high voltage electric power transmission lines constitutes an economically significant waste of energy for utilities.  In high voltage equipment like cathode ray tube televisions, radio transmitters, X-ray machines, and particle accelerators, the current leakage caused by coronas can constitute an unwanted load on the circuit. In the air, coronas generate gases such as ozone (O₃) and nitric oxide (NO), and in turn, nitrogen dioxide (NO₂), and thus nitric acid (HNO₃) if water vapor is present. These gases are corrosive and can degrade and embrittle nearby materials, and are also toxic to humans and the environment.
  Corona discharges can often be suppressed by improved insulation, corona rings, and making high voltage electrodes in smooth rounded shapes. However, controlled corona discharges are used in a variety of processes such as air filtration, photocopiers, and ozone generators.
caption: Long exposure photograph of corona discharge on an insulator string of a 500 kV overhead power line.  Corona discharges represent a significant power loss for  electric utilities.
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