Time-domain and frequency-domain characteristics of audible noise from single corona source

In this paper, the time-domain measurement method for audible noise is employed to study the time and frequency domains characteristics of audible noise generated by single corona discharge under DC and AC voltage in a coaxial geometry. The results show that in time-domain the audible noise from positive and negative corona discharge both consist of a series of random sound pressure pulses and the amplitudes of sound pressure pulses from positive corona discharge are larger than those from negative corona discharge. As for the audible noise from AC corona discharge in the test, it has a periodic component with a 50Hz fundamental frequency accompanied by sound pressure pulse trains mainly near the negative peaks of AC voltage. When the applied voltage is further increased, sound pressure pulses may be generated at the positive half-cycle. The asymmetrical waveforms in positive and negative half-cycle of AC voltage may attribute to the influence of the space charges. Besides, the discrete wavelet transform (DWT) is used to analyze the detailed characteristics and the difference of corona-generated noise and the background noise. Furthermore, the frequency-domain characteristics of audible noise from DC and AC corona are analyzed based on the time-domain results. This presented work hopefully will be a useful reference for further theoretical studies of the audible noise caused by corona discharge.