Experimental analysis of corona inception voltage under combined AC-DC voltages at various air pressure and humidity in rod to plane electrode

Abstract

As the effect of climate plays a significant role on corona discharge under combined voltages, the variation of corona inception voltage with different air pressure and humidity is studied. The experimental platform based on rod-to-plane electrode is constructed with adjustable air pressure from 0.06MPa to 0.10 MPa and the relative humidity (RH) from 20% to 90%. The variation of ultraviolet (UV) photon count and corona inception voltage is obtained at various climate conditions under different applied voltages: the single alternate current (AC), single direct current (DC), and combined AC-DC. It turns out that all the corona inception voltages decline with the drop of air pressure and the rise of humidity under different applied voltages. The influence between different voltages mainly relies on space charge, as more AC component makes it easier to accumulate positive ions. The existence of AC makes ions move forward and backward while the existence of DC dominates the polarity of corona and general drift directions. At last the fitting formula of hybrid corona inception voltage combining air pressure and relative humidity is given.