D P Kothari is currently Director-in-Charge, Indian Institute of Technology(IIT), Delhi. Before that, he was Deputy Director (Administration), Professor of Electrical Engineering and Head, Centre for Energy Studies at IIT Delhi. During the period of 1997-98, he was Principal, VRCE, Nagpur. In 1982-83 and in 1989, he taught at the Royal Melbourne Institute of Technology, Melbourne, Australia as a Visiting Fellow. He obtained his BE, ME and Ph D degrees from BITS, Pilani and has been involved in teaching and research since 1977 at IIT, Delhi. He has published and presented more than 500 papers in prestigious national and international journals and conferences. Prof. Kothari is also a Fellow of the Institution of Engineers [India] and Senior Member, IEEE. He has co-authored more than 17 books including Power System Engineering, Modern Power System Analysis, 3/e, Basic Electrical Engineering, 2/e and Theory and Problems of Electric Machines [TMH Outline Series] 2/e. His research inter-ests include power system control, optimization, reliability and energy conservation.

The author can be contacted at dpk0710@yahoo.com

I J Nagrath is Adjunct Professor, BITS, Pilani and retired as Professor of Electrical Engineering and Deputy Director of Birla Institute of Technology and Science, Pilani. He obtained his BE with Hons in electrical engineering from the University of Rajas-than in 1951 and MS from the University of Wisconsin in 1956. He has co-authored several successful books which include Power System Engineering, Modern Power System Analysis, 3/e, Systems: Modelling and Analysis, Theory and Problems of Electric Machines [TMH Outline Series] 2/e and Basic Electrical Engineer-ing, 2/e [all published by TMH]. He has also published several research papers in prestigious national and international jour-nals.