Light spectra on DC corona

The present paper has carried out an experiment on a test setup of needle-plate electrodes under DC voltage. Raising the applied voltage gradually, the corona spectra from the onset streamer to the breakdown streamer have been measured, The measured spectra range from 300 nm to 800 nm. The experiment has shown some regularities of corona spectra. For example, the UV spectra appears first when raising applied voltage gradually, then the longer wavelength spectra appear. Furthermore, compared with those spectra measured on a long air gap by the Les Renardieres Group, some new spectral wavelengths have been found. These results are of important significance both in theory and practice of insulation monitoring