Study of the transient regime of the corona discharge generated by a triode electrode arrangement

Extensive research has been carried out on the electrostatic charging of the non-woven media for air filters. Nevertheless, the transient regime of corona charging of these media is a topic that still needs to be explored. The primarily aim of this paper is to study this phenomenon in the particular case of the corona discharge generated by a triode-type electrode arrangement. In the first set of measurements, the polypropylene non-woven media was subjected to positive or negative corona discharge generated by such an electrode arrangement, energized from a DC high-voltage source. The measured physical quantities were the electric current I m at the plate surface (with and without the sample in contact with the grounded plate) during the corona discharge process, for a duration of 30 s through a resistor R m = 10 MΩ connected between the metallic plate and the ground connection. The electrometer was interfaced with a computer to perform data acquisition using a virtual instrument developed in the LabView environment. The current I m stabilize after 5 s and was higher for an electrode without sample in contact with the grounded. The second set of experiments were similar to the first set of measurements except for the fact that the current in different areas of the grounded electrode was measured using a special designed printed circuit board (PCB) plate with seven strip current probes. The electrometer was connected as previously explained, in order to visualize the transient regime of corona current at different probes. The experimental results pointed out that the charging process is affected by the capacitance introduced by the media in the equivalent electric circuit of the triode electrode system.