Contents

• Unit I. (i) Breakdown in Gases: Introduction to mechanism of breakdown in gases, Townsend’s breakdown mechanism. Breakdown in electromagnetic gases. Application of gases in power system.

  
  (ii) Breakdown in Liquids: Introduction to mechanism of breakdown in liquids, suspended solid particle mechanism and cavity breakdown. Application of oil in power apparatus.

  (iii) Breakdown in solids: Introduction to mechanism of breakdown in solids, electromechanical breakdown, treeing & tracking breakdown and thermal breakdown.

   

  
  Unit 2. (i) High DC Voltage Generation: Generation of high dc voltage, basic voltage multiplier circuit.
  (ii) High AC Voltage Generation: Cascaded Transformers.
  (iii) Impulse Voltage generation: Impulse voltage, basic impulse circuit, Mark’s multistage impulse generator.
  (iv) Measurement of High Voltage: Potential dividers - resistive, capacitive and mixed potential dividers. Sphere gap- Construction and operation, Klydonorgraph.

   

  
  Unit 3. Nondestructive Insulation Tests: (i) Measurement of resistivity, dielectric constant and loss factor. High Voltage Schering Bridge- measurement of capacitance and dielectric loss.
  (ii) Partial Discharges: Introduction to partial discharge, partial discharge equivalent circuit, Basic wide-band and narrow band PD detection circuits.

   

  Unit 4. (i) Over voltages: Causes of over voltages, introduction to lightning phenomena, over voltages due to lighting.
  (ii) Travelling Waves: Travelling waves on transmission lines-open end line, short circuited line, line terminated through a resistance, line connected to a cable, reflection and refraction at a T-junction and line terminated through a capacitance, Attenuation of tavelling waves.

   

  
  Unit 5. (i) Over Voltage Protection: Basic construction and operation of ground wires- protection angle and protective zone, ground rods, counterpoise, surge absorber, rod gap and arcing horn, lighting arresters - expulsion type, non - linear gap type and metal oxide gapless type.

  (ii) Insulation Coordination: Volt - time curves, basic impulse insulation
  levels, coordination of insulation levels.