MODULE 1 Introduction to Electrical Discharges by ASSOC.PROF DR ZOLKAFLE BIN BUNTAT

Type of Electrical Discharge Corona Discharge Partial Discharge Surface Discharge Glow Discharge Dielectric Barrier Discharge Pulsed Streamer Discharge

Corona Discharge Fig. 1a and1b Corona discharge is an incomplete discharge process using a DC voltage supply. Corona discharges are relatively low power (less than 100 W) and occur at or near atmospheric pressure. Characterised by very low current (10-10 A – 10-5 A) and very high voltage (2 kV-5 kV), and Normally take place in the Townsend dark discharge region.

Corona Discharge (cont.) The corona is invariably generated by strong electric fields associated with small diameter wires, needles, or sharp edges on an electrode as shown in Fig. 1a and b

Corona Discharge (cont.)

Partial Discharge Partial Discharge (PD) is a localised dielectric breakdown of a small portion of a solid or fluid electrical insulation system under high voltage stress, which does not bridge the space between two conductors.

Surface Discharge Surface discharge is discharge occur on the surface of dielectric material i.e insulator.

Glow Discharge Glow Discharge is a plasma in which a partially ionized gas consists of nearly equal concentrations of positive and negative charges and a large number of neutral species. It is formed either in a cell filled with gas (inert or molecular) at low pressure or in a gas gap at atmospheric pressure, between two parallel plate electrodes covered with dielectric plates.

Glow Discharge

Glow Discharge (cont.) In general, very difficult to obtain a stable glow discharge generated between two gaps. The atmospheric pressure glow discharge is thought to be stable only if three simple requirement are fulfilled: (i) use of a source frequency over 1 kHz (ii) insertion of dielectric plates between the two metal electrodes, and (iii) use of a helium dilution gas.

Dielectric Barrier Discharge (DBD) Dielectric-barrier discharge (DBD) is the electrical discharge between two electrode separated by an insulating dielectric barrier

Dielectric Barrier Discharge

Pulsed Streamer Discharge Pulsed Streamer discharge is generated similar to dielectric barrier discharge. The input power supply is pulsed power supply.

Electrical discharge applications Electrical discharge also known as plasma discharge. It can be used in many application. The following are list of the common applications: i.) Ozone Generation

Electrical discharge applications ii) Surface modification by increasing the surface energy of fabrics, films, and solid materials by exposure to a atmospheric pressure glow discharge.

Electrical discharge applications iii) Sterilizing surfaces for healthcare, medical, tooth cleaning and food processing applications.

Electrical discharge applications iv.) Removal of soot, Nox, SOx and volatile organic compounds from diesel engine exhaust and etc

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