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 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, spectra of ultra-violet first appear, raising applied voltage gradually, then appear longer wavelength spectra. Furthermore, compared with those spectra measured on long air gap by Les Renardieres Group, some new wavelengths of spectra have been found. All these are of important significance both in theory and in practice of insulation monitor.