An experimental study of the wires-two plates is presented in this paper. The principal running of these types of electrostatic
precipitators is based on the corona discharge on which depend their performances. The factors affecting corona formation on
wire - to- plate gaps are investigated experimentally. There are many factors affecting such corona formation. The investigated
factors were the interspace between the two wires, gap length between the wire and the plate, ambient temperature, relative
humidity, polarity or frequency of the applied voltage, and electrode material. In order to study and explain such phenomena,
simultaneous measurements of both the applied voltage and the corona current were introduced. Several design parameters have
been taken into consideration especially the numbers of active electrodes and their diameter. Current-voltage curves are
particularly analyzed. Experimental results show that discharge current is strongly affected by the active electrode diameters.