High Voltage Engineering
(Advanced)
Arsalan A RahimUniversity of Engineering & Technology
Lahore, Pakistan
Lecture # 1
Basics of High Voltage
Course Books• High Voltage and Electrical Insulation Engineering
(June 2011 Edition) by Ravindra & Wolfgang (IEEE Press)
• High Voltage Engineering Fundamentals (2nd Edition) by E.Kuffel, W.S.Zaengl, J.Kuffel
Reference Books• Advances in High Voltage Engineering (IET) Edited by
A.Haddad & D.Warne • High Voltage Engineering by C.L. Wadhwa• High Voltage Engineering by M.S.Naidu (4th Edition)
All books available for Download at ep.nge.com.pk (Course Page)
Why High Voltage (Engineering)?
It’s the knowledge of the behavior of dielectrics (insulator) — electrical insulation when subjected to high voltage
Result is to minimize the volume of the electrical insulation requirements and trouble-free life of high voltage apparatus.
A totally different Domain (Engineering) when High Voltage are applied. Stray Capacitances & Inductances come into play.
No concept of a complete Insulator – Even a good Insulator can conduct under High Voltages
Basic Definitions to Start With
• Electron• Proton• Ion• Ionization• Electric Charge • Space Charge• Volume Charge Density ρv
• Electric Discharge• Electric & Magnetic Field• Electromagnetics
Di-Electric & Electric Material
• What the difference between these ?
• Electric Material – capable of developing (conducting) electric charge or current
• Di-Electric Material – not capable of developing (conducting) electric charge or current but admits electrostatic and magnetic lines of force
• Di-Electric Material Properties– Relative Permittivity εr , Type of Material & Amplitude of Voltage Applied
Electrical Breakdown
• Failure of Electrical Insulation Properties (flow of current) of an Insulator or Di-electric
Local Breakdownconfined locally to a
part of an Insulator(Partial Breakdown)
Global Breakdowncomplete rupture or failure of insulator
properties(Electrical Breakdown)
Corona:• Stable Partial Breakdown (PB) in
Gaseous Di-electrics
Partial Electrical Breakdown (discharge)
Streamer:Extension of Corona at Distance
Shower of Discharge (Streamer Corona)
• Types: Audible & Visible Corona
Example: Discharge of Cloud (Lightning)
Aurora:• Luminous phenomenon consisting of streamers
or Arches of Light at Polar Regions• Explained under “Faraday’s Glow”
• Aurora Australis (Southern Hemisphere)
• Aurora Borealis (Northern Hemisphere)
• Atoms in Ionosphere stuck by High Energy Electrons Coming from Sun (cosmic Radiation)
Aurora:
Di-electric Property: Capacitance
• Is the field between the plates of a Capacitor Uniform?
• Permittivity of a Di-electric is Constant ?
Stray Capacitance
• How to minimize it?
Electric Field
• Electric Field Intensity
• Electric Charge is considered static when there is no movement of charge
• Field produced by Static charge or Direct Voltage is known as Electro-static field
• Field produced by power frequency Alternating voltage is known as quasi-stationary Electric field
Dielectric Breakdown depends on
• Composition of dielectric material, presence of impurities imperfections in the dielectric
• Pressure • Humidity • Temperature • Electric field configuration (shape of the electrodes, their size and
gap distance)• Electrode material • Duration• Magnitude and the waveform of the applied voltage
Today’s Text Covered from Chapter 1 + Uptil Article 2.3.1 from Chapter 2
of IEEE Press Book (Ravindra Book)
and
Chapter 1 of Kuffel Book