Electrical Insulation and Dielectrics in Repetitive Pulsed Power
Dielectrics are the fundamental building blocks of electrical insulation for centuries. Many components in power systems must be electrically insulated for proper functionality. Although dielectric materials have been studied in every aspect of science and technology from chemistry, physics, utility power, and advance electric power systems, as the systems became large and complicated, higher electrical stresses are imposed onto dielectrics and insulation. Continuous partial discharge or corona activities are a serious problem usually associated with insulation degradation, electromagnetic interference (EMI), and the upset of poorly protected sensitive circuits without proper shielding. For example, in space/aerospace context the influence of factors such as reduced ambient pressures, outgassing, existence of ionosphere and space plasma must also be considered, along with high frequency and localized high field stresses on insulation. This presentation is an overview of dielectric material fundamentals, including the high voltage electrical insulation of space power and high voltage pulsed systems over the years. The studies of pertinent high voltage effects on insulation including theory, technology development, and applications that encompasses phenomena such as high electric field stress, high magnetic flux, and high frequency issues relating to the performance of all insulation media are also presented.
Gaseous Breakdown at High Frequencies
In general, power devices and systems operating in vacuum or sub-atmospheric pressures are more susceptible to partial discharges, corona, or volume discharges due to the partial vacuum conditions. In space power systems, for example, these activities are usually are great concerns and require major design considerations. Currently space power systems operate voltages higher than the traditional 28 V. With the availability of high power electronic devices operating at higher switching frequencies, these power systems also operate under frequencies and waveforms quite different from those studied and developed for earthbound power distribution systems. Thus, these advancements make the corona and partial discharge problems more important than before. This presentation is an overview of systems and components subject non-uniform, high frequency and high fields operated in sub-atmospheric pressures and associated high frequency gaseous breakdown. Also reviewed are the breakdown characteristics of gases, such as helium, nitrogen and air, under unipolar repetitively pulsed voltage at frequencies varying from 10 kHz to 240 kHz in partial vacuum. Comparison with dc and unipolar kHz frequency sinusoidal fields is also discussed. Breakdown voltage as a function of pressure in the range where “Pashce” minimum occurs, along with optical emission characteristics of plasma at breakdown are presented.
Hulya Kirkici is a Professor of Electrical and Computer Engineering, Auburn University, where she teaches and conducts research. She received the B.S. and M.S. in physics from Middle East Technical University (METU), Ankara, Turkey; and the Ph.D. in electrical engineering from Polytechnic University (NYU – Poly), Brooklyn, NY in 1990. She was a visiting scientist/engineer at NASA, Marshall Space Flight Center, Huntsville, AL (1999-2000), and a visiting scholar / consultant at the Wright Patterson Air Force Base – Research Laboratory during Fall 2014.
Dr. Kirkici’s research interests are in electrical insulation and high-frequency dielectric breakdown in space and aerospace environments, cold plasmas, repetitive pulsed power, and high voltage engineering. She has published numerous journal and conference papers and given invited talks in these related topics over the years (in USA, Turkey, Japan, South Korea, and China). Dr. Kirkici is a Senior Member of IEEE, and members of American Physical Society (APS), Sigma Xi Scientific Honor Society, Eta Kappa Nu Electrical Engineering Honor Society, and American Association of University Women (AAUW).
Dr. Kirkici is a recipient of the IEEE William G. Dunbar Award “for continuing contribution to high-voltage and high frequency insulation research and engineering education,” presented at the 2014 IEEE International Power Modulator and High Voltage Conference, in June 2014; and a recipient of the IEEE Sol Schneider Award “for continuing technical and administrative leadership in the power modulator and high voltage communities,” from IEEE-IPMHVC in 2010. Dr. Kirkici was the Invited Plenary speaker at the Chinese Pulse Power Summer School in Mianyang, China (August 2014) and was the IEEE Distinguished Lecturer at the 2011 IEEE Panel of Conference Organizers (POCO) meeting in Beijing, and delivered a talk titled “Novel Dielectrics and Advanced Electrical Insulation Technology.”
Currently, Dr. Kirkici is Vice President of IEEE Sensosr Council (2014-2015) and serves on the IEEE Publication Services and Products Board as a member-at-large (2013-present). Dr. Kirkici was the Treasurer and Finance Chair of IEEE Publication Services and Products Board (PSPB) and a member of IEEE Finance Committee (2011-2014). She was a member of the TAB Finance Committee (2011-2012) and a Member of IEEE Conferences committee (2011-2012). She served as the President of IEEE Dielectrics and Electrical Insulation Society (2009 and 2010). Dr.Kirkici was the General Chair of the IEEE-Power Modulator Conference (2004) and the Chair of the IEEE-High Voltage Workshop (2002). She has been an Associate Editor of the IEEE-Transactions on Dielectrics and Electrical Insulation (1998-2007 and 2012 to present) and served as a Co-Guest Editor of the IEEE-Transactions on Plasma Science, Pulsed Power Science and Technology (Oct. 2002) and Power Modulators and Repetitive Pulsed Power (Aug. 2005) and Co-Guest Editor of IEEE Trans on Dielectrics and Electrical Insulation, Power Modulators and Repetitive Pulsed Power (Aug. 2009) Special Issues.