Effect of voltage waveform on partial discharge in ferroelectric pellet layer for gas cleaning

Thermal power plant flue gas cleaning utilizing plasma chemical reactions promoted with partial discharges is studied. Characteristics of a partial discharge in a ferroelectric pellet layer have been studied using AC voltages with varying frequency or using square-wave voltages. The capacitance of the layer, C/sub t/, consists of the capacitance of the ferroelectric pellet, C/sub p/, and the capacitance of the air gap between each pellet, C/sub g/. Since C/sub g/ is much smaller than C/sub p/, the capacitance of the layer is determined mainly by C/sub p/. Therefore, packing of ferroelectric pellets with large dielectric constant values does not increase the value of C/sub t/ significantly, and excessive increase in the capacitive charging current can be avoided. With AC voltage application, the partial discharge takes place when the voltage crosses zero and ceases when the voltage reaches positive or negative peak value. When a square wave voltage is applied, a very large current can be obtained during the transient period of the voltage.<>