Dielectrics and Electrical Insulation

Theory of gases. Photoelectric, thermal and field emission. Ionization by collision, photoionization, thermal ionization and ionization by x-rays and cosmic rays. Deionization becuase of recombination, negative ion formation, and diffusion. Behaviour of charged particles in electric fields of low E/P and high E/P (E=electric field and P=pressure). Breakdown Processes: Townsend mechanism, secondary effect, streamer formation from self sustained discharges to breakdown, breakdown in non-uniform fields, temporal development of breakdown, partial breakdown or corona discharges. Solid and Liquid Dielectrics: Types of solid and liquid insulating materials, their electrical thermal, chemical and mechanical properties; charge transport; surface discharges; breakdown mechanisms; effects of impurities on breakdown strength. Electrohydrodynamics and its influence on breakdown mechanisms in liquids; electromechanical and intrinsic breakdown strength of solids. Recommended Background: Basic knowledge of physics of materials for Electrical Engineers (ECE 209 or equivalent). Familiarity with electrical power system components is useful.