High Voltage Engineering

UNIT I: Breakdown in Gases Gases as insulating media, Ionization processes, Electron avalanche, Townsend’s criterion for breakdown, streamer theory of breakdown, Gaseous discharge in uniform field, Paschen’s law, Breakdown in non-uniform field, corona discharges, effect of polarity on corona & breakdown voltage. Corona in transmission lines, Empirical formulae for corona loss, Methods of reducing corona loss. UNIT II: Dielectrics Liquid Dielectrics: conduction & breakdown in pure liquids, Conduction & breakdown in commercial liquids, Methods for determination of breakdown strength. Factors affecting dielectric strength of liquids. Solid Dielectrics: -Breakdown mechanism, Intrinsic breakdown, Electromechanical breakdown, thermal breakdown, breakdown of solid dielectric in practice, Breakdown due to treeing & tracking, breakdown due to the internal discharges. UNIT III: Generation of high voltages Generation of high D.C. voltages, half wave & full wave rectifier circuits, Van De Graff generators, Electro-static Generators, Generation of high alternating voltages, cascade transformers, Generation of impulse voltages, Multistage Impulse generator, Marx circuit, Tripping & control of Impulse generators UNIT IV: Measurement of high Voltages Measurement of high D.C.voltage, Measurement of high A.C.& impulse voltages, series Impedance voltmeter, series capacitance voltmeter capacitance potential dividers & capacitance voltage transformers, Resistance potential dividers, Electrostatic voltmeter, Spark gap for measurement of high D.C., A.C. & impulse voltages, Potential divider for impulse voltage measurements, CRO for impulse voltage measurements. UNIT V: High Voltage Testing of Electrical Apparatus: Test on insulators, Dry & wet flash Over tests & withstand tests, Impulse flash over & withstand voltage test, High voltage tests on cables Impulse testing of transformers. Non-Destructive Testing: Measurement of dielectric constant & loss factor, High voltage Schering Bridge, Partial Discharge Measurements. Text Books: 1. High Voltage Engineering by M.S. Naidu & V.Kamraju, TMH Pbs. 2. An introduction to high voltage enginnering, Subir Ray, PHI. Reference Books: 1. High voltage Insulation Engineering by Ravindra Arora, New Age International. 2. High Voltage Engineering By Dr.R.S.Jha, Dhanpat Rai & Sons. 3. Extra High Voltage A.C. Transmission Engineering by R.D. Begamudre Wiley Eastern Limited. 4. High voltage Engineering by D. V. Razevig and Chaurasia, khanna pbs.