Corona and Arcing in Power and RF Devices

The electric field between the surface of two conductors exceeds a critical value, a self sustaining ionizing discharge that typically occurs between the closest surface areas called corona. The corona initiates arcing and the arcing can ignite fire. There is both power loss and generation of RF interference during corona. Under certain circumstances corona could shorten the service-life of electrical insulations. The corona due to high frequency is still a research topic. Some studies indicate that corona due to RF fields occur at lower voltages compared to power frequencies. If the onset of corona is minimized, the arcing in electronic and electrical systems would be automatically eliminated. This paper describes corona onset characteristics under temperature, pressure and humidity changes in AC, DC and RF circuits. The multipacting discharge phenomena that occur in high voltage high RF frequency circuits also discussed. A frequency domain technique for measuring corona onset is also discussed. The corona due to AC power voltages is modeled as RC equivalent circuit and rise time of corona is computed.