(For BEJBTech AMIE UPSC

5th Revised Edition

El ower

(For BEBTech AMIE IETE GATE UPSC Engineering Services)

5th Revised Edition

Ashfaq Husain 1-rrna1 Reader in Electrical c-----

Polytechnic Muslim (India

CB

CBS Publishers amp Distributors Pvt Ltd

New Delhi bull Bengaiuru bull Chennai bull Kochi bull Kolkata bull Mumbai Hyderabad bull Nagpur bull Patna bull Pune bull Vijayawada

ISBN 81-239-1448-2

Third Edition 1990

Reprint 1992 1993 Fourth Edition 1994

Reprint 1996 1997 1999 2000 2001 2003 2004 2005 200b Fifth Edition 2007

Reprint 20082009201020112012201420152017

Copyrightcopy Ashfaq Husain

All 1ights reserved No part of this book may be reproduced or transmitted in any form or by any means electronic or mechanical including photocopying recording or any information storage and retrieval system without permission in writing from the publisher

Published by Satish Kumar Jain for CBS Publishers amp Distributors Pvt Ltd 4819XI Prahl ad Street 24 Ansari Road Daryaganj New Delhi - 110002 delhicbspdcom cbspubsairtelmailin bull wwwcbspdcom Ph 232892592326686123266867 bull Fax 011-23243014

Curporate Office 204 FIE Industrial Area Patparganj Delhi - 110 092 Ph49344934bull Fax Ol l-49344935 E-mail publishingcbspdcom bull publicity(a)cbspdcom

Branches Bengaluru 2975 17th Cross KR Road Bansankari 2nd Stage Bengaluru - 70 bull Ph +9 l-80-2677167879 bull Fax --91-80-26771680 E-mail cbsbnggrnailcom bangalorecbspdcomChennai No 7 Subbaraya Street Shenoy Nagar Chennai middot 600030Ph +91-44-26681266 26680620 bull Fax +91-44-42032115E-mail chennaicbspdcomKocii Ashana House 3()1904 AM Thomas Road ValanjambalamEmakulum Kochi bull Ph +9 l -484-4059061-65Fax +91-484-4059065 bull E-mail cochincbspdcomKolkata 6-B Ground Floor Rameshwar Shaw Road Kolkata - 700014Ph +91-33-22891126178 bull E-mail kolkatacbspdcomMumbai 83-C Dr E Moses Road Worli Mumbai - 400018Ph +91-9833017933 022-2490234041 bull E-mail mumbaicbspdcom

Representatives

bull Hyderabad 0-9885175004 bull Nagpur 0-9021734563bull Patna 0-9334159340 bull Pune 0-9623451994

bull Vijayawada 0-9000660880

Printed at India Binding House Noida UP (lnda)

El ower

(For BEBTech AMIE IETE GATE UPSC Engineering Services)

5th Revised Edition

Ashfaq Husain 1-rrna1 Reader in Electrical c-----

Polytechnic Muslim (India

CB

CBS Publishers amp Distributors Pvt Ltd

New Delhi bull Bengaiuru bull Chennai bull Kochi bull Kolkata bull Mumbai Hyderabad bull Nagpur bull Patna bull Pune bull Vijayawada

ISBN 81-239-1448-2

Third Edition 1990

Reprint 1992 1993 Fourth Edition 1994

Reprint 1996 1997 1999 2000 2001 2003 2004 2005 200b Fifth Edition 2007

Reprint 20082009201020112012201420152017

Copyrightcopy Ashfaq Husain

All 1ights reserved No part of this book may be reproduced or transmitted in any form or by any means electronic or mechanical including photocopying recording or any information storage and retrieval system without permission in writing from the publisher

Published by Satish Kumar Jain for CBS Publishers amp Distributors Pvt Ltd 4819XI Prahl ad Street 24 Ansari Road Daryaganj New Delhi - 110002 delhicbspdcom cbspubsairtelmailin bull wwwcbspdcom Ph 232892592326686123266867 bull Fax 011-23243014

Curporate Office 204 FIE Industrial Area Patparganj Delhi - 110 092 Ph49344934bull Fax Ol l-49344935 E-mail publishingcbspdcom bull publicity(a)cbspdcom

Branches Bengaluru 2975 17th Cross KR Road Bansankari 2nd Stage Bengaluru - 70 bull Ph +9 l-80-2677167879 bull Fax --91-80-26771680 E-mail cbsbnggrnailcom bangalorecbspdcomChennai No 7 Subbaraya Street Shenoy Nagar Chennai middot 600030Ph +91-44-26681266 26680620 bull Fax +91-44-42032115E-mail chennaicbspdcomKocii Ashana House 3()1904 AM Thomas Road ValanjambalamEmakulum Kochi bull Ph +9 l -484-4059061-65Fax +91-484-4059065 bull E-mail cochincbspdcomKolkata 6-B Ground Floor Rameshwar Shaw Road Kolkata - 700014Ph +91-33-22891126178 bull E-mail kolkatacbspdcomMumbai 83-C Dr E Moses Road Worli Mumbai - 400018Ph +91-9833017933 022-2490234041 bull E-mail mumbaicbspdcom

Representatives

bull Hyderabad 0-9885175004 bull Nagpur 0-9021734563bull Patna 0-9334159340 bull Pune 0-9623451994

bull Vijayawada 0-9000660880

Printed at India Binding House Noida UP (lnda)

ISBN 81-239-1448-2

Third Edition 1990

Reprint 1992 1993 Fourth Edition 1994

Reprint 1996 1997 1999 2000 2001 2003 2004 2005 200b Fifth Edition 2007

Reprint 20082009201020112012201420152017

Copyrightcopy Ashfaq Husain

All 1ights reserved No part of this book may be reproduced or transmitted in any form or by any means electronic or mechanical including photocopying recording or any information storage and retrieval system without permission in writing from the publisher

Published by Satish Kumar Jain for CBS Publishers amp Distributors Pvt Ltd 4819XI Prahl ad Street 24 Ansari Road Daryaganj New Delhi - 110002 delhicbspdcom cbspubsairtelmailin bull wwwcbspdcom Ph 232892592326686123266867 bull Fax 011-23243014

Curporate Office 204 FIE Industrial Area Patparganj Delhi - 110 092 Ph49344934bull Fax Ol l-49344935 E-mail publishingcbspdcom bull publicity(a)cbspdcom

Branches Bengaluru 2975 17th Cross KR Road Bansankari 2nd Stage Bengaluru - 70 bull Ph +9 l-80-2677167879 bull Fax --91-80-26771680 E-mail cbsbnggrnailcom bangalorecbspdcomChennai No 7 Subbaraya Street Shenoy Nagar Chennai middot 600030Ph +91-44-26681266 26680620 bull Fax +91-44-42032115E-mail chennaicbspdcomKocii Ashana House 3()1904 AM Thomas Road ValanjambalamEmakulum Kochi bull Ph +9 l -484-4059061-65Fax +91-484-4059065 bull E-mail cochincbspdcomKolkata 6-B Ground Floor Rameshwar Shaw Road Kolkata - 700014Ph +91-33-22891126178 bull E-mail kolkatacbspdcomMumbai 83-C Dr E Moses Road Worli Mumbai - 400018Ph +91-9833017933 022-2490234041 bull E-mail mumbaicbspdcom

Representatives

bull Hyderabad 0-9885175004 bull Nagpur 0-9021734563bull Patna 0-9334159340 bull Pune 0-9623451994

bull Vijayawada 0-9000660880

Printed at India Binding House Noida UP (lnda)

P R E FA CE

Preface to

the Fifth Edition

This book is intended to serve as a textbook for the course Electrical Power Systems for BTech BE degree students of Electrical Engineering It will also serve as a text reference for students of Diploma in Electrical Engineering The common topics included in the syllabi of almost all Engishyneering Institutions in India are covered in this book

This text is also useful for candidates appearing in AMIE GATE UPSC Engineering services and other competitive examinations The practising engineers would also find this book valuable a1 a concise reference for basic principles and applications in Electrical Power Systems

This book brings many widely varied topics together It lays emphasis on the basic concepts ana at the same time introduces modem methods of solution of power system problems

The book is divided into twenty eight chapters Each chapter is self-contained and is dealt with comprehensively The subject matter in each chapter has been developed systematically from basic principles using the SI system of units Generalized approach has been given in treatments

The fifth edition has been thoroughly revised further enlarged and updated

In response to the suggestions from the teachers and students the following new chapters are incorporated in this revised edition

bull Voltage stability

bull Flexible AC Transmission System (FACTS)

Chapters on Line Insulators and Supports Per Unit Representation ong Transmission LinesEconomic Operation of Power Systems Unsymmetrical Faults Power System Stability Overvoltage Protection HYDC Transmission have been rewritten to include the recent trends in the subject

The numerous ii lustrative examples enhance the utility of the text and make it easy fOi the beginner to thoroughly grasp the presentation of the theory The worked-out exampls are very carefully selected in the text to illustrate the practical applications Most simplified methods of solving the problems are given Step-by-step procedures of solving problems are provided At the end of each chapter a large number of problems of wide variety have been included for practice

v

vi Preface to the Fifth Edition

With all these modifications the book has become well organised up-to-date lucid and very easy to follow for self study

The author hopes that the new fifth edition will continue to help and will enhance the undershystanding of Electrical Power Systems in the same way that previous editions have done in the past

It is hoped that the book will be useful to students and teachers alike

The author would be grateful to readers for their suggesticns for further improvement of the book

Ashfaq Husain

Acknowledgements I appreciate the patience understanding and support of my wife Dr Nigar Minhaj Reader in Elecshytronics Womens Polytechnic Aligarh Muslim University Aligarh Her valuable suggestions and comments have made it possible for me to complete this book

I also appreciate the patience and concern of my sons Ahmad Ashfaq MTech (Environmental Engineering) Lecturer in Civil Engineering University Polytechnic Aligarh Muslim University Aligarh and Haroon Ashfaq MTech (Electrical Engineering) Lecturer in Electrical Engineering lamia Millia Islamia New Delhi who has helped me a lot in the revision of this book Haroon Ashfaq has given valuable suggestions and made a lot of contribution to this book

Ashfaq Husain

PREFACE

Preface to

the First Edition

This book has been designed as a textbook for engineering degree diploma AMIE or equivalent examinations in Electrical Power Systems in India and abroad It will alsgt be useful to students preparing for various competitive examinations It is equally helpful to pra tising engineers to unshyderstand the theoretical aspects of their profession

The book includes the recent rapid developments that are taking place iJ the field of Electrica Power Systems which are not at present readily available in a single textbock because of the divershysity of the topics The present book brings many widely varied topics toget er to cater to the needs of revised syllabi of engineering and competitive examinations Besides this book bridges the gap between old and new concepts in Electrical Power Systems The text lays emphasis on the basic concepts and at the same time introduces modern methods of solution of p wer system problems

The book is divided into twenty-three chapters Each chapter is self-conained and is dealt with comprehensively The subject matter in each chapter has been developed sy tematically from basic principles using the SI system of units Generalized approach has been given in treatments Matrix analysis is used wherever necessary The technical information available on he topics is up-to-date

The chapters on Conductors Insulators and Power Cables are written svecially with a view to put before the reader recent developments in this important field which - as not attracted much attention by previous authors Clear diagrams and photographs are given fcr tetter understanding The concepts of GMD and GMR which are necessary for handling calculati ns for lines having any conductor configuration are clearly discussed Performance of short me ium and long lines is adequately explained The chapter on General Network Constants gives the performance calculashytions of transmission lines by general methods It emphasizes a unified ap roach to the problems instead of various partial solutions The subject matter on Power Circle Diarams covers analytical as well as graphical methods to demonstrate clearly the actual performance of lines

In view of the importance of High Voltage Direct Current (HVDC) trarsmission in the present Juncture of technological development in the subject a chapter on Power ransmission by Direct Current is included in the text

vii

viii Preface to the First Edition

The mechanical performance of overhead lines under various operating conditions is fully disshycussed The chapters on Load Flow Studies and Economic Operation of Power Systems are meant to introduce the basIc aspects of the problems involved in this area

Throughout the text the importance of extra high voltage transmission of energy is discussed in detail Recent developments regarding the choice of next higher voltages standardization of transshymission voltages are presented One full chapter is devoted to the comprehensive treatment of Coshyrona Emphasis has been laid on generalized treatment of fault analysis instead of partial solution

The chapters on Travelling Waves and Power System Stability have been discussed exhausshytively

The numerous illustrative examples enhance the utility of the text and make it easy for the beginner to thoroughly grasp the presentation of the theory The worked-out examples are very carefully selected in the text to illustrate the practical applications Most 3implified methods of solving the problems are given In most cases the worked-out examples illustrate the technique of solving problems At the end of each chapter a large number of representative numerical examples of wide variety have been included for practice Many of them have been selected from the past examination papers of standard institutions The problems are of practical nature

While utmost care has been exercised to eliminate misprints and errors the author would feel obliged to have mistakes brought to his notice He would welcome any comments and suggestions for the improvement of book

Ashfaq Husain

CONTENTS

Contents

Preface to the Fifth Edition V

Preface to the First Edition VII

1 Load Characteristics I-IS 11 Introduction J I 2 Advantages of eJectricri energy 13 Load J I 4 Connected load 2 J5 Demand 2 16 Demand interval 2 17 Maximum demand (MD) or peak load 2 18 Demand factor (DF) 2 19 Average load or average demand 3 I 10 Load factor 3 111 Diversity factor FD 3

11 2 Load diversity 4 113 Utilization factor F tl 4

1 14 Plant factor or capacity factor 4 1 15 Loss factor hs 5 1 16 Load curve 5 117 Informations obtained from load curves j

1 18 Utility of load curves 6 1 19 Load-duration curve 6 120 Procedure for plotting the load-duration curve 6 121 Informations avai lable from load duration curve 0

ix

x Contents

2 Supply Systems 16 - 35

2 I Introduction 16 22 Basic structure of an AC power system 16 23 Distribution voltage level 16 24 Subtransmiss ion level 17 25 Transmi ssion level 17 26 Layout of a power supply network 17 27 System interconnection 18 28 System voltage and transmission efficIency 19 29 Working voltage 20 210 Choice of the next high voltage 20 2 I I Standardization of transmission voltages 21 2 12 Classification of lines 21 213 Comparison of conductor costs in various systems 22

2 13 I Criterion of equal maximum voltage to earth 23 2132 Criterion of equal maximum voltage between line

conductors 27

3 Conductors 36 - 54

31 Introduction 36 32 Types of conductors 37

321 Hard-drawn copper conductors 37 322 Cadmium copper conductor 37 323 Steel-cored copper conductor (SCC) 38 324 Copperweld conductor 38 325 Hard-drawn aluminium conductor or all -aluminium

conductor (AAC) 38 326 Aluminium conductor steel reinforced (ACSR) 38 327 Smooth tyengtdy ACSR conductor 39 328 Expandeq ACSR conductor 40 32Y All-aluminium allay conductor (AAAC) 40 3210 ACAR conductor 40 321 I Alumoweld conductor 41 3212 Phosphor-bronze conductor 41 32 13 Galvanized stee l conductt)r 41

33 Resistance 41 34 Skin effect 42

35 Equivalent coppe r section 43 36 Kelvins economy law 43 37 Modified Kelvins law 44 38 Graphical representation 45 39 Economic current density 46 310 Determination of losses 49 311 Limitations of Kelvin s law 52

Contents xi

4 Power Cables 55-92~

41 Introduction 55 42 Cable construction 56 43 Conductors 56 44 Insulation 57 45 Sheath 58 46 Protective covering 58 47 Belted cable 59 48 Screened cable 59 49 Cable impregnation 60 410 Non-drained cables 60 4 II Dielectric stress 60 4 12 Grading of cables 64 413 Cable capacitance 70 414 Charging current or capacitive current 70 415 Capacitances in a three-core belted cable 70 4 16 Measurement of Cc and Cs 72 4 17 Insulation resistance 74 4 18 Dielectric loss 75

4181 Conductivity of insulation 75 418 2 Dielectric hysteresis or dielectric absorption 75 4183 Corona or gaseous ionization in cables 76 4184 Dielectric power loss 76

419 Stress distribution in a HYDC cable 78 420 Skin effect 79 421 Proximity effect 79 422 Current rating of cables 79

4221 Normal or safe current carrying capacity 79 422 2 Over current rating 8 4223 Short-circuit rating 82

4 23 Thermal breakdown 82 424 Soil thermal resistivity 82 425 Extra high voltage cables 82 4 26 Oil-filled cables 83

4261 Advantages of self-contained oil-filled cables 85 4262 Advantages of oil-filled cables 85 4263 Oil for cables 85

427 Gas-pressure cables 86 427 1 External gas-pressure cables 86 4272 Internal gas-pressure cables 86

428 Compressed gas insulated cables (GIC) 87 429 Advantages of GIC over oil-filled cables 88 430 Cross-linked polyethylene (XLPE) cables 89 4 3 Power cable installation 89

6

xii Co tents

5 Line Insulators and Supports 93 - 122

5 Introduction 93 5 Types of insulator 95

521 Pin type insulator 95 522 Suspension insulators 96 523 Strain or tension insulators 97

5 V -strings 98 5 Insulator materials 98

541 Polymer insulator 99 5~ Voltage distribution and string efficiency 99

551 Alternative method 101 5 t Improving voltage distribution 103 5 Selection of insulation 112 5 t Line supports 113 5 ~ Wood poles 114 5 m Concrete poles 114 5 I I Steel poles 115 5 1l2 Supporting towers 115

5121 Self-supporting towers 115 5 122 Guyed or stayed towers 115

5 0 Vibration of conductors 117 513 I Resonant vibration 117 513 2 Galloping 1J8 5133 Dancing and steel-jump 118

51+ Effects of vibration on the transmission line 1J8 515 Prevention of vibration 119

5151 Armour rods 119 5152 Stockbridge damper 119

51 5 Spacing of conductors 120

Sa and Tension 123 - 150 61 Introduction 123 62 Sag and tension 123 63 Parabolic method 124 64 Catenary method 125 65 Accuracy of results 1)8 66 Loading on conductors 128 67 Conductor clearance from ground 1J I 68 Erection sag and tension 132

681 Factors affecting the sag 133 69 Spans of unequal length 137 61 Sag and tension charts 138 61 Supports at unequal leves 139 61 The sag template 144 61 = Preparation of the sag template 145 61 c Method of using the template 146 6 1 Economic span length 147

7

8

Contents xiii

Line Parameters 151- 212 7 J Introduction 151 77 Line inductance 151 7 3 Inductance of a conductor 152

731 Internal inductance 152 732 External inductance 154

74 Flux linkages in a group of conductors 155 75 Inductance of a two-wire line 157 76 Inductance of symmetrical three-phase line 159 77 Inductance of unsymmetrical three-phase line 160 78 Method of geometric mean distances 163 79 Two-wire line 165 710 Symmetrical three-phase line 165 7 11 Inductance of unsymmetrical three-phase line 166 7 12 Inductance of double-circuit single-phase line 169 7 13 Inductance of double-circuit three-phase lines 170 714 Special cases of double-circuit lines 172 7 15 Inductance of bundled conductor lines 174 716 Line capacitance 178 7 17 Electric field of a long straight conductor 178 718 System of conductors 179 719 Capacitance of two-wire line 180 720 Capacitance of the symmetrical three-phase line 182 721 Capacitance of an unsymmetrical three-phase transposed line 183 722 Capacitance of a three-phase single-circuit untransposed line 186 723 Charging current 187 724 Capacitance by GMD method 188 725 Capacitance of double-circuit three-phase line 189 726 Effect of earth on the line capacitance 190 727 Effect of earth on capacitance of single-circuit three-phase line

with transposition 193 728 Capacitance of bundled conductor lines 195 7 29 Shunt conductance 198 730 Interference between power and communication lines 198 7 31 Electromagnetic effect 198 732 Electrostatic effect 199

Per Unit Representation 213 - 237

81 Introduction 213 82 Change of base 2 J 6 83 Per unit impedance of a transformer 216 84 Per unit quantities in three-phase systems 219 85 Selection of base values 221 86 Base quantities in terms of kV and MVA 221 87 Per unit load impedance 222

Electrical Power System

Publisher CBS Publications ISBN 9788123914480 Author Ashfaq Hussain

Type the URL httpwwwkopykitabcomproduct10371

Get this eBook

vi Preface to the Fifth Edition

With all these modifications the book has become well organised up-to-date lucid and very easy to follow for self study

The author hopes that the new fifth edition will continue to help and will enhance the undershystanding of Electrical Power Systems in the same way that previous editions have done in the past

It is hoped that the book will be useful to students and teachers alike

The author would be grateful to readers for their suggesticns for further improvement of the book

Ashfaq Husain

Acknowledgements I appreciate the patience understanding and support of my wife Dr Nigar Minhaj Reader in Elecshytronics Womens Polytechnic Aligarh Muslim University Aligarh Her valuable suggestions and comments have made it possible for me to complete this book

I also appreciate the patience and concern of my sons Ahmad Ashfaq MTech (Environmental Engineering) Lecturer in Civil Engineering University Polytechnic Aligarh Muslim University Aligarh and Haroon Ashfaq MTech (Electrical Engineering) Lecturer in Electrical Engineering lamia Millia Islamia New Delhi who has helped me a lot in the revision of this book Haroon Ashfaq has given valuable suggestions and made a lot of contribution to this book

Ashfaq Husain

PREFACE

Preface to

the First Edition

This book has been designed as a textbook for engineering degree diploma AMIE or equivalent examinations in Electrical Power Systems in India and abroad It will alsgt be useful to students preparing for various competitive examinations It is equally helpful to pra tising engineers to unshyderstand the theoretical aspects of their profession

The book includes the recent rapid developments that are taking place iJ the field of Electrica Power Systems which are not at present readily available in a single textbock because of the divershysity of the topics The present book brings many widely varied topics toget er to cater to the needs of revised syllabi of engineering and competitive examinations Besides this book bridges the gap between old and new concepts in Electrical Power Systems The text lays emphasis on the basic concepts and at the same time introduces modern methods of solution of p wer system problems

The book is divided into twenty-three chapters Each chapter is self-conained and is dealt with comprehensively The subject matter in each chapter has been developed sy tematically from basic principles using the SI system of units Generalized approach has been given in treatments Matrix analysis is used wherever necessary The technical information available on he topics is up-to-date

The chapters on Conductors Insulators and Power Cables are written svecially with a view to put before the reader recent developments in this important field which - as not attracted much attention by previous authors Clear diagrams and photographs are given fcr tetter understanding The concepts of GMD and GMR which are necessary for handling calculati ns for lines having any conductor configuration are clearly discussed Performance of short me ium and long lines is adequately explained The chapter on General Network Constants gives the performance calculashytions of transmission lines by general methods It emphasizes a unified ap roach to the problems instead of various partial solutions The subject matter on Power Circle Diarams covers analytical as well as graphical methods to demonstrate clearly the actual performance of lines

In view of the importance of High Voltage Direct Current (HVDC) trarsmission in the present Juncture of technological development in the subject a chapter on Power ransmission by Direct Current is included in the text

vii

viii Preface to the First Edition

The mechanical performance of overhead lines under various operating conditions is fully disshycussed The chapters on Load Flow Studies and Economic Operation of Power Systems are meant to introduce the basIc aspects of the problems involved in this area

Throughout the text the importance of extra high voltage transmission of energy is discussed in detail Recent developments regarding the choice of next higher voltages standardization of transshymission voltages are presented One full chapter is devoted to the comprehensive treatment of Coshyrona Emphasis has been laid on generalized treatment of fault analysis instead of partial solution

The chapters on Travelling Waves and Power System Stability have been discussed exhausshytively

The numerous illustrative examples enhance the utility of the text and make it easy for the beginner to thoroughly grasp the presentation of the theory The worked-out examples are very carefully selected in the text to illustrate the practical applications Most 3implified methods of solving the problems are given In most cases the worked-out examples illustrate the technique of solving problems At the end of each chapter a large number of representative numerical examples of wide variety have been included for practice Many of them have been selected from the past examination papers of standard institutions The problems are of practical nature

While utmost care has been exercised to eliminate misprints and errors the author would feel obliged to have mistakes brought to his notice He would welcome any comments and suggestions for the improvement of book

Ashfaq Husain

CONTENTS

Contents

Preface to the Fifth Edition V

Preface to the First Edition VII

1 Load Characteristics I-IS 11 Introduction J I 2 Advantages of eJectricri energy 13 Load J I 4 Connected load 2 J5 Demand 2 16 Demand interval 2 17 Maximum demand (MD) or peak load 2 18 Demand factor (DF) 2 19 Average load or average demand 3 I 10 Load factor 3 111 Diversity factor FD 3

11 2 Load diversity 4 113 Utilization factor F tl 4

1 14 Plant factor or capacity factor 4 1 15 Loss factor hs 5 1 16 Load curve 5 117 Informations obtained from load curves j

1 18 Utility of load curves 6 1 19 Load-duration curve 6 120 Procedure for plotting the load-duration curve 6 121 Informations avai lable from load duration curve 0

ix

x Contents

2 Supply Systems 16 - 35

2 I Introduction 16 22 Basic structure of an AC power system 16 23 Distribution voltage level 16 24 Subtransmiss ion level 17 25 Transmi ssion level 17 26 Layout of a power supply network 17 27 System interconnection 18 28 System voltage and transmission efficIency 19 29 Working voltage 20 210 Choice of the next high voltage 20 2 I I Standardization of transmission voltages 21 2 12 Classification of lines 21 213 Comparison of conductor costs in various systems 22

2 13 I Criterion of equal maximum voltage to earth 23 2132 Criterion of equal maximum voltage between line

conductors 27

3 Conductors 36 - 54

31 Introduction 36 32 Types of conductors 37

321 Hard-drawn copper conductors 37 322 Cadmium copper conductor 37 323 Steel-cored copper conductor (SCC) 38 324 Copperweld conductor 38 325 Hard-drawn aluminium conductor or all -aluminium

conductor (AAC) 38 326 Aluminium conductor steel reinforced (ACSR) 38 327 Smooth tyengtdy ACSR conductor 39 328 Expandeq ACSR conductor 40 32Y All-aluminium allay conductor (AAAC) 40 3210 ACAR conductor 40 321 I Alumoweld conductor 41 3212 Phosphor-bronze conductor 41 32 13 Galvanized stee l conductt)r 41

33 Resistance 41 34 Skin effect 42

35 Equivalent coppe r section 43 36 Kelvins economy law 43 37 Modified Kelvins law 44 38 Graphical representation 45 39 Economic current density 46 310 Determination of losses 49 311 Limitations of Kelvin s law 52

Contents xi

4 Power Cables 55-92~

41 Introduction 55 42 Cable construction 56 43 Conductors 56 44 Insulation 57 45 Sheath 58 46 Protective covering 58 47 Belted cable 59 48 Screened cable 59 49 Cable impregnation 60 410 Non-drained cables 60 4 II Dielectric stress 60 4 12 Grading of cables 64 413 Cable capacitance 70 414 Charging current or capacitive current 70 415 Capacitances in a three-core belted cable 70 4 16 Measurement of Cc and Cs 72 4 17 Insulation resistance 74 4 18 Dielectric loss 75

4181 Conductivity of insulation 75 418 2 Dielectric hysteresis or dielectric absorption 75 4183 Corona or gaseous ionization in cables 76 4184 Dielectric power loss 76

419 Stress distribution in a HYDC cable 78 420 Skin effect 79 421 Proximity effect 79 422 Current rating of cables 79

4221 Normal or safe current carrying capacity 79 422 2 Over current rating 8 4223 Short-circuit rating 82

4 23 Thermal breakdown 82 424 Soil thermal resistivity 82 425 Extra high voltage cables 82 4 26 Oil-filled cables 83

4261 Advantages of self-contained oil-filled cables 85 4262 Advantages of oil-filled cables 85 4263 Oil for cables 85

427 Gas-pressure cables 86 427 1 External gas-pressure cables 86 4272 Internal gas-pressure cables 86

428 Compressed gas insulated cables (GIC) 87 429 Advantages of GIC over oil-filled cables 88 430 Cross-linked polyethylene (XLPE) cables 89 4 3 Power cable installation 89

6

xii Co tents

5 Line Insulators and Supports 93 - 122

5 Introduction 93 5 Types of insulator 95

521 Pin type insulator 95 522 Suspension insulators 96 523 Strain or tension insulators 97

5 V -strings 98 5 Insulator materials 98

541 Polymer insulator 99 5~ Voltage distribution and string efficiency 99

551 Alternative method 101 5 t Improving voltage distribution 103 5 Selection of insulation 112 5 t Line supports 113 5 ~ Wood poles 114 5 m Concrete poles 114 5 I I Steel poles 115 5 1l2 Supporting towers 115

5121 Self-supporting towers 115 5 122 Guyed or stayed towers 115

5 0 Vibration of conductors 117 513 I Resonant vibration 117 513 2 Galloping 1J8 5133 Dancing and steel-jump 118

51+ Effects of vibration on the transmission line 1J8 515 Prevention of vibration 119

5151 Armour rods 119 5152 Stockbridge damper 119

51 5 Spacing of conductors 120

Sa and Tension 123 - 150 61 Introduction 123 62 Sag and tension 123 63 Parabolic method 124 64 Catenary method 125 65 Accuracy of results 1)8 66 Loading on conductors 128 67 Conductor clearance from ground 1J I 68 Erection sag and tension 132

681 Factors affecting the sag 133 69 Spans of unequal length 137 61 Sag and tension charts 138 61 Supports at unequal leves 139 61 The sag template 144 61 = Preparation of the sag template 145 61 c Method of using the template 146 6 1 Economic span length 147

7

8

Contents xiii

Line Parameters 151- 212 7 J Introduction 151 77 Line inductance 151 7 3 Inductance of a conductor 152

731 Internal inductance 152 732 External inductance 154

74 Flux linkages in a group of conductors 155 75 Inductance of a two-wire line 157 76 Inductance of symmetrical three-phase line 159 77 Inductance of unsymmetrical three-phase line 160 78 Method of geometric mean distances 163 79 Two-wire line 165 710 Symmetrical three-phase line 165 7 11 Inductance of unsymmetrical three-phase line 166 7 12 Inductance of double-circuit single-phase line 169 7 13 Inductance of double-circuit three-phase lines 170 714 Special cases of double-circuit lines 172 7 15 Inductance of bundled conductor lines 174 716 Line capacitance 178 7 17 Electric field of a long straight conductor 178 718 System of conductors 179 719 Capacitance of two-wire line 180 720 Capacitance of the symmetrical three-phase line 182 721 Capacitance of an unsymmetrical three-phase transposed line 183 722 Capacitance of a three-phase single-circuit untransposed line 186 723 Charging current 187 724 Capacitance by GMD method 188 725 Capacitance of double-circuit three-phase line 189 726 Effect of earth on the line capacitance 190 727 Effect of earth on capacitance of single-circuit three-phase line

with transposition 193 728 Capacitance of bundled conductor lines 195 7 29 Shunt conductance 198 730 Interference between power and communication lines 198 7 31 Electromagnetic effect 198 732 Electrostatic effect 199

Per Unit Representation 213 - 237

81 Introduction 213 82 Change of base 2 J 6 83 Per unit impedance of a transformer 216 84 Per unit quantities in three-phase systems 219 85 Selection of base values 221 86 Base quantities in terms of kV and MVA 221 87 Per unit load impedance 222

Electrical Power System

Publisher CBS Publications ISBN 9788123914480 Author Ashfaq Hussain

Type the URL httpwwwkopykitabcomproduct10371

Get this eBook

PREFACE

Preface to

the First Edition

This book has been designed as a textbook for engineering degree diploma AMIE or equivalent examinations in Electrical Power Systems in India and abroad It will alsgt be useful to students preparing for various competitive examinations It is equally helpful to pra tising engineers to unshyderstand the theoretical aspects of their profession

The book includes the recent rapid developments that are taking place iJ the field of Electrica Power Systems which are not at present readily available in a single textbock because of the divershysity of the topics The present book brings many widely varied topics toget er to cater to the needs of revised syllabi of engineering and competitive examinations Besides this book bridges the gap between old and new concepts in Electrical Power Systems The text lays emphasis on the basic concepts and at the same time introduces modern methods of solution of p wer system problems

The book is divided into twenty-three chapters Each chapter is self-conained and is dealt with comprehensively The subject matter in each chapter has been developed sy tematically from basic principles using the SI system of units Generalized approach has been given in treatments Matrix analysis is used wherever necessary The technical information available on he topics is up-to-date

The chapters on Conductors Insulators and Power Cables are written svecially with a view to put before the reader recent developments in this important field which - as not attracted much attention by previous authors Clear diagrams and photographs are given fcr tetter understanding The concepts of GMD and GMR which are necessary for handling calculati ns for lines having any conductor configuration are clearly discussed Performance of short me ium and long lines is adequately explained The chapter on General Network Constants gives the performance calculashytions of transmission lines by general methods It emphasizes a unified ap roach to the problems instead of various partial solutions The subject matter on Power Circle Diarams covers analytical as well as graphical methods to demonstrate clearly the actual performance of lines

In view of the importance of High Voltage Direct Current (HVDC) trarsmission in the present Juncture of technological development in the subject a chapter on Power ransmission by Direct Current is included in the text

vii

viii Preface to the First Edition

The mechanical performance of overhead lines under various operating conditions is fully disshycussed The chapters on Load Flow Studies and Economic Operation of Power Systems are meant to introduce the basIc aspects of the problems involved in this area

Throughout the text the importance of extra high voltage transmission of energy is discussed in detail Recent developments regarding the choice of next higher voltages standardization of transshymission voltages are presented One full chapter is devoted to the comprehensive treatment of Coshyrona Emphasis has been laid on generalized treatment of fault analysis instead of partial solution

The chapters on Travelling Waves and Power System Stability have been discussed exhausshytively

The numerous illustrative examples enhance the utility of the text and make it easy for the beginner to thoroughly grasp the presentation of the theory The worked-out examples are very carefully selected in the text to illustrate the practical applications Most 3implified methods of solving the problems are given In most cases the worked-out examples illustrate the technique of solving problems At the end of each chapter a large number of representative numerical examples of wide variety have been included for practice Many of them have been selected from the past examination papers of standard institutions The problems are of practical nature

While utmost care has been exercised to eliminate misprints and errors the author would feel obliged to have mistakes brought to his notice He would welcome any comments and suggestions for the improvement of book

Ashfaq Husain

CONTENTS

Contents

Preface to the Fifth Edition V

Preface to the First Edition VII

1 Load Characteristics I-IS 11 Introduction J I 2 Advantages of eJectricri energy 13 Load J I 4 Connected load 2 J5 Demand 2 16 Demand interval 2 17 Maximum demand (MD) or peak load 2 18 Demand factor (DF) 2 19 Average load or average demand 3 I 10 Load factor 3 111 Diversity factor FD 3

11 2 Load diversity 4 113 Utilization factor F tl 4

1 14 Plant factor or capacity factor 4 1 15 Loss factor hs 5 1 16 Load curve 5 117 Informations obtained from load curves j

1 18 Utility of load curves 6 1 19 Load-duration curve 6 120 Procedure for plotting the load-duration curve 6 121 Informations avai lable from load duration curve 0

ix

x Contents

2 Supply Systems 16 - 35

2 I Introduction 16 22 Basic structure of an AC power system 16 23 Distribution voltage level 16 24 Subtransmiss ion level 17 25 Transmi ssion level 17 26 Layout of a power supply network 17 27 System interconnection 18 28 System voltage and transmission efficIency 19 29 Working voltage 20 210 Choice of the next high voltage 20 2 I I Standardization of transmission voltages 21 2 12 Classification of lines 21 213 Comparison of conductor costs in various systems 22

2 13 I Criterion of equal maximum voltage to earth 23 2132 Criterion of equal maximum voltage between line

conductors 27

3 Conductors 36 - 54

31 Introduction 36 32 Types of conductors 37

321 Hard-drawn copper conductors 37 322 Cadmium copper conductor 37 323 Steel-cored copper conductor (SCC) 38 324 Copperweld conductor 38 325 Hard-drawn aluminium conductor or all -aluminium

conductor (AAC) 38 326 Aluminium conductor steel reinforced (ACSR) 38 327 Smooth tyengtdy ACSR conductor 39 328 Expandeq ACSR conductor 40 32Y All-aluminium allay conductor (AAAC) 40 3210 ACAR conductor 40 321 I Alumoweld conductor 41 3212 Phosphor-bronze conductor 41 32 13 Galvanized stee l conductt)r 41

33 Resistance 41 34 Skin effect 42

35 Equivalent coppe r section 43 36 Kelvins economy law 43 37 Modified Kelvins law 44 38 Graphical representation 45 39 Economic current density 46 310 Determination of losses 49 311 Limitations of Kelvin s law 52

Contents xi

4 Power Cables 55-92~

41 Introduction 55 42 Cable construction 56 43 Conductors 56 44 Insulation 57 45 Sheath 58 46 Protective covering 58 47 Belted cable 59 48 Screened cable 59 49 Cable impregnation 60 410 Non-drained cables 60 4 II Dielectric stress 60 4 12 Grading of cables 64 413 Cable capacitance 70 414 Charging current or capacitive current 70 415 Capacitances in a three-core belted cable 70 4 16 Measurement of Cc and Cs 72 4 17 Insulation resistance 74 4 18 Dielectric loss 75

4181 Conductivity of insulation 75 418 2 Dielectric hysteresis or dielectric absorption 75 4183 Corona or gaseous ionization in cables 76 4184 Dielectric power loss 76

419 Stress distribution in a HYDC cable 78 420 Skin effect 79 421 Proximity effect 79 422 Current rating of cables 79

4221 Normal or safe current carrying capacity 79 422 2 Over current rating 8 4223 Short-circuit rating 82

4 23 Thermal breakdown 82 424 Soil thermal resistivity 82 425 Extra high voltage cables 82 4 26 Oil-filled cables 83

4261 Advantages of self-contained oil-filled cables 85 4262 Advantages of oil-filled cables 85 4263 Oil for cables 85

427 Gas-pressure cables 86 427 1 External gas-pressure cables 86 4272 Internal gas-pressure cables 86

428 Compressed gas insulated cables (GIC) 87 429 Advantages of GIC over oil-filled cables 88 430 Cross-linked polyethylene (XLPE) cables 89 4 3 Power cable installation 89

6

xii Co tents

5 Line Insulators and Supports 93 - 122

5 Introduction 93 5 Types of insulator 95

521 Pin type insulator 95 522 Suspension insulators 96 523 Strain or tension insulators 97

5 V -strings 98 5 Insulator materials 98

541 Polymer insulator 99 5~ Voltage distribution and string efficiency 99

551 Alternative method 101 5 t Improving voltage distribution 103 5 Selection of insulation 112 5 t Line supports 113 5 ~ Wood poles 114 5 m Concrete poles 114 5 I I Steel poles 115 5 1l2 Supporting towers 115

5121 Self-supporting towers 115 5 122 Guyed or stayed towers 115

5 0 Vibration of conductors 117 513 I Resonant vibration 117 513 2 Galloping 1J8 5133 Dancing and steel-jump 118

51+ Effects of vibration on the transmission line 1J8 515 Prevention of vibration 119

5151 Armour rods 119 5152 Stockbridge damper 119

51 5 Spacing of conductors 120

Sa and Tension 123 - 150 61 Introduction 123 62 Sag and tension 123 63 Parabolic method 124 64 Catenary method 125 65 Accuracy of results 1)8 66 Loading on conductors 128 67 Conductor clearance from ground 1J I 68 Erection sag and tension 132

681 Factors affecting the sag 133 69 Spans of unequal length 137 61 Sag and tension charts 138 61 Supports at unequal leves 139 61 The sag template 144 61 = Preparation of the sag template 145 61 c Method of using the template 146 6 1 Economic span length 147

7

8

Contents xiii

Line Parameters 151- 212 7 J Introduction 151 77 Line inductance 151 7 3 Inductance of a conductor 152

731 Internal inductance 152 732 External inductance 154

74 Flux linkages in a group of conductors 155 75 Inductance of a two-wire line 157 76 Inductance of symmetrical three-phase line 159 77 Inductance of unsymmetrical three-phase line 160 78 Method of geometric mean distances 163 79 Two-wire line 165 710 Symmetrical three-phase line 165 7 11 Inductance of unsymmetrical three-phase line 166 7 12 Inductance of double-circuit single-phase line 169 7 13 Inductance of double-circuit three-phase lines 170 714 Special cases of double-circuit lines 172 7 15 Inductance of bundled conductor lines 174 716 Line capacitance 178 7 17 Electric field of a long straight conductor 178 718 System of conductors 179 719 Capacitance of two-wire line 180 720 Capacitance of the symmetrical three-phase line 182 721 Capacitance of an unsymmetrical three-phase transposed line 183 722 Capacitance of a three-phase single-circuit untransposed line 186 723 Charging current 187 724 Capacitance by GMD method 188 725 Capacitance of double-circuit three-phase line 189 726 Effect of earth on the line capacitance 190 727 Effect of earth on capacitance of single-circuit three-phase line

with transposition 193 728 Capacitance of bundled conductor lines 195 7 29 Shunt conductance 198 730 Interference between power and communication lines 198 7 31 Electromagnetic effect 198 732 Electrostatic effect 199

Per Unit Representation 213 - 237

81 Introduction 213 82 Change of base 2 J 6 83 Per unit impedance of a transformer 216 84 Per unit quantities in three-phase systems 219 85 Selection of base values 221 86 Base quantities in terms of kV and MVA 221 87 Per unit load impedance 222

Electrical Power System

Publisher CBS Publications ISBN 9788123914480 Author Ashfaq Hussain

Type the URL httpwwwkopykitabcomproduct10371

Get this eBook

viii Preface to the First Edition

The mechanical performance of overhead lines under various operating conditions is fully disshycussed The chapters on Load Flow Studies and Economic Operation of Power Systems are meant to introduce the basIc aspects of the problems involved in this area

Throughout the text the importance of extra high voltage transmission of energy is discussed in detail Recent developments regarding the choice of next higher voltages standardization of transshymission voltages are presented One full chapter is devoted to the comprehensive treatment of Coshyrona Emphasis has been laid on generalized treatment of fault analysis instead of partial solution

The chapters on Travelling Waves and Power System Stability have been discussed exhausshytively

The numerous illustrative examples enhance the utility of the text and make it easy for the beginner to thoroughly grasp the presentation of the theory The worked-out examples are very carefully selected in the text to illustrate the practical applications Most 3implified methods of solving the problems are given In most cases the worked-out examples illustrate the technique of solving problems At the end of each chapter a large number of representative numerical examples of wide variety have been included for practice Many of them have been selected from the past examination papers of standard institutions The problems are of practical nature

While utmost care has been exercised to eliminate misprints and errors the author would feel obliged to have mistakes brought to his notice He would welcome any comments and suggestions for the improvement of book

Ashfaq Husain

CONTENTS

Contents

Preface to the Fifth Edition V

Preface to the First Edition VII

1 Load Characteristics I-IS 11 Introduction J I 2 Advantages of eJectricri energy 13 Load J I 4 Connected load 2 J5 Demand 2 16 Demand interval 2 17 Maximum demand (MD) or peak load 2 18 Demand factor (DF) 2 19 Average load or average demand 3 I 10 Load factor 3 111 Diversity factor FD 3

11 2 Load diversity 4 113 Utilization factor F tl 4

1 14 Plant factor or capacity factor 4 1 15 Loss factor hs 5 1 16 Load curve 5 117 Informations obtained from load curves j

1 18 Utility of load curves 6 1 19 Load-duration curve 6 120 Procedure for plotting the load-duration curve 6 121 Informations avai lable from load duration curve 0

ix

x Contents

2 Supply Systems 16 - 35

2 I Introduction 16 22 Basic structure of an AC power system 16 23 Distribution voltage level 16 24 Subtransmiss ion level 17 25 Transmi ssion level 17 26 Layout of a power supply network 17 27 System interconnection 18 28 System voltage and transmission efficIency 19 29 Working voltage 20 210 Choice of the next high voltage 20 2 I I Standardization of transmission voltages 21 2 12 Classification of lines 21 213 Comparison of conductor costs in various systems 22

2 13 I Criterion of equal maximum voltage to earth 23 2132 Criterion of equal maximum voltage between line

conductors 27

3 Conductors 36 - 54

31 Introduction 36 32 Types of conductors 37

321 Hard-drawn copper conductors 37 322 Cadmium copper conductor 37 323 Steel-cored copper conductor (SCC) 38 324 Copperweld conductor 38 325 Hard-drawn aluminium conductor or all -aluminium

conductor (AAC) 38 326 Aluminium conductor steel reinforced (ACSR) 38 327 Smooth tyengtdy ACSR conductor 39 328 Expandeq ACSR conductor 40 32Y All-aluminium allay conductor (AAAC) 40 3210 ACAR conductor 40 321 I Alumoweld conductor 41 3212 Phosphor-bronze conductor 41 32 13 Galvanized stee l conductt)r 41

33 Resistance 41 34 Skin effect 42

35 Equivalent coppe r section 43 36 Kelvins economy law 43 37 Modified Kelvins law 44 38 Graphical representation 45 39 Economic current density 46 310 Determination of losses 49 311 Limitations of Kelvin s law 52

Contents xi

4 Power Cables 55-92~

41 Introduction 55 42 Cable construction 56 43 Conductors 56 44 Insulation 57 45 Sheath 58 46 Protective covering 58 47 Belted cable 59 48 Screened cable 59 49 Cable impregnation 60 410 Non-drained cables 60 4 II Dielectric stress 60 4 12 Grading of cables 64 413 Cable capacitance 70 414 Charging current or capacitive current 70 415 Capacitances in a three-core belted cable 70 4 16 Measurement of Cc and Cs 72 4 17 Insulation resistance 74 4 18 Dielectric loss 75

4181 Conductivity of insulation 75 418 2 Dielectric hysteresis or dielectric absorption 75 4183 Corona or gaseous ionization in cables 76 4184 Dielectric power loss 76

419 Stress distribution in a HYDC cable 78 420 Skin effect 79 421 Proximity effect 79 422 Current rating of cables 79

4221 Normal or safe current carrying capacity 79 422 2 Over current rating 8 4223 Short-circuit rating 82

4 23 Thermal breakdown 82 424 Soil thermal resistivity 82 425 Extra high voltage cables 82 4 26 Oil-filled cables 83

4261 Advantages of self-contained oil-filled cables 85 4262 Advantages of oil-filled cables 85 4263 Oil for cables 85

427 Gas-pressure cables 86 427 1 External gas-pressure cables 86 4272 Internal gas-pressure cables 86

428 Compressed gas insulated cables (GIC) 87 429 Advantages of GIC over oil-filled cables 88 430 Cross-linked polyethylene (XLPE) cables 89 4 3 Power cable installation 89

6

xii Co tents

5 Line Insulators and Supports 93 - 122

5 Introduction 93 5 Types of insulator 95

521 Pin type insulator 95 522 Suspension insulators 96 523 Strain or tension insulators 97

5 V -strings 98 5 Insulator materials 98

541 Polymer insulator 99 5~ Voltage distribution and string efficiency 99

551 Alternative method 101 5 t Improving voltage distribution 103 5 Selection of insulation 112 5 t Line supports 113 5 ~ Wood poles 114 5 m Concrete poles 114 5 I I Steel poles 115 5 1l2 Supporting towers 115

5121 Self-supporting towers 115 5 122 Guyed or stayed towers 115

5 0 Vibration of conductors 117 513 I Resonant vibration 117 513 2 Galloping 1J8 5133 Dancing and steel-jump 118

51+ Effects of vibration on the transmission line 1J8 515 Prevention of vibration 119

5151 Armour rods 119 5152 Stockbridge damper 119

51 5 Spacing of conductors 120

Sa and Tension 123 - 150 61 Introduction 123 62 Sag and tension 123 63 Parabolic method 124 64 Catenary method 125 65 Accuracy of results 1)8 66 Loading on conductors 128 67 Conductor clearance from ground 1J I 68 Erection sag and tension 132

681 Factors affecting the sag 133 69 Spans of unequal length 137 61 Sag and tension charts 138 61 Supports at unequal leves 139 61 The sag template 144 61 = Preparation of the sag template 145 61 c Method of using the template 146 6 1 Economic span length 147

7

8

Contents xiii

Line Parameters 151- 212 7 J Introduction 151 77 Line inductance 151 7 3 Inductance of a conductor 152

731 Internal inductance 152 732 External inductance 154

74 Flux linkages in a group of conductors 155 75 Inductance of a two-wire line 157 76 Inductance of symmetrical three-phase line 159 77 Inductance of unsymmetrical three-phase line 160 78 Method of geometric mean distances 163 79 Two-wire line 165 710 Symmetrical three-phase line 165 7 11 Inductance of unsymmetrical three-phase line 166 7 12 Inductance of double-circuit single-phase line 169 7 13 Inductance of double-circuit three-phase lines 170 714 Special cases of double-circuit lines 172 7 15 Inductance of bundled conductor lines 174 716 Line capacitance 178 7 17 Electric field of a long straight conductor 178 718 System of conductors 179 719 Capacitance of two-wire line 180 720 Capacitance of the symmetrical three-phase line 182 721 Capacitance of an unsymmetrical three-phase transposed line 183 722 Capacitance of a three-phase single-circuit untransposed line 186 723 Charging current 187 724 Capacitance by GMD method 188 725 Capacitance of double-circuit three-phase line 189 726 Effect of earth on the line capacitance 190 727 Effect of earth on capacitance of single-circuit three-phase line

with transposition 193 728 Capacitance of bundled conductor lines 195 7 29 Shunt conductance 198 730 Interference between power and communication lines 198 7 31 Electromagnetic effect 198 732 Electrostatic effect 199

Per Unit Representation 213 - 237

81 Introduction 213 82 Change of base 2 J 6 83 Per unit impedance of a transformer 216 84 Per unit quantities in three-phase systems 219 85 Selection of base values 221 86 Base quantities in terms of kV and MVA 221 87 Per unit load impedance 222

Electrical Power System

Publisher CBS Publications ISBN 9788123914480 Author Ashfaq Hussain

Type the URL httpwwwkopykitabcomproduct10371

Get this eBook

CONTENTS

Contents

Preface to the Fifth Edition V

Preface to the First Edition VII

1 Load Characteristics I-IS 11 Introduction J I 2 Advantages of eJectricri energy 13 Load J I 4 Connected load 2 J5 Demand 2 16 Demand interval 2 17 Maximum demand (MD) or peak load 2 18 Demand factor (DF) 2 19 Average load or average demand 3 I 10 Load factor 3 111 Diversity factor FD 3

11 2 Load diversity 4 113 Utilization factor F tl 4

1 14 Plant factor or capacity factor 4 1 15 Loss factor hs 5 1 16 Load curve 5 117 Informations obtained from load curves j

1 18 Utility of load curves 6 1 19 Load-duration curve 6 120 Procedure for plotting the load-duration curve 6 121 Informations avai lable from load duration curve 0

ix

x Contents

2 Supply Systems 16 - 35

2 I Introduction 16 22 Basic structure of an AC power system 16 23 Distribution voltage level 16 24 Subtransmiss ion level 17 25 Transmi ssion level 17 26 Layout of a power supply network 17 27 System interconnection 18 28 System voltage and transmission efficIency 19 29 Working voltage 20 210 Choice of the next high voltage 20 2 I I Standardization of transmission voltages 21 2 12 Classification of lines 21 213 Comparison of conductor costs in various systems 22

2 13 I Criterion of equal maximum voltage to earth 23 2132 Criterion of equal maximum voltage between line

conductors 27

3 Conductors 36 - 54

31 Introduction 36 32 Types of conductors 37

321 Hard-drawn copper conductors 37 322 Cadmium copper conductor 37 323 Steel-cored copper conductor (SCC) 38 324 Copperweld conductor 38 325 Hard-drawn aluminium conductor or all -aluminium

conductor (AAC) 38 326 Aluminium conductor steel reinforced (ACSR) 38 327 Smooth tyengtdy ACSR conductor 39 328 Expandeq ACSR conductor 40 32Y All-aluminium allay conductor (AAAC) 40 3210 ACAR conductor 40 321 I Alumoweld conductor 41 3212 Phosphor-bronze conductor 41 32 13 Galvanized stee l conductt)r 41

33 Resistance 41 34 Skin effect 42

35 Equivalent coppe r section 43 36 Kelvins economy law 43 37 Modified Kelvins law 44 38 Graphical representation 45 39 Economic current density 46 310 Determination of losses 49 311 Limitations of Kelvin s law 52

Contents xi

4 Power Cables 55-92~

41 Introduction 55 42 Cable construction 56 43 Conductors 56 44 Insulation 57 45 Sheath 58 46 Protective covering 58 47 Belted cable 59 48 Screened cable 59 49 Cable impregnation 60 410 Non-drained cables 60 4 II Dielectric stress 60 4 12 Grading of cables 64 413 Cable capacitance 70 414 Charging current or capacitive current 70 415 Capacitances in a three-core belted cable 70 4 16 Measurement of Cc and Cs 72 4 17 Insulation resistance 74 4 18 Dielectric loss 75

4181 Conductivity of insulation 75 418 2 Dielectric hysteresis or dielectric absorption 75 4183 Corona or gaseous ionization in cables 76 4184 Dielectric power loss 76

419 Stress distribution in a HYDC cable 78 420 Skin effect 79 421 Proximity effect 79 422 Current rating of cables 79

4221 Normal or safe current carrying capacity 79 422 2 Over current rating 8 4223 Short-circuit rating 82

4 23 Thermal breakdown 82 424 Soil thermal resistivity 82 425 Extra high voltage cables 82 4 26 Oil-filled cables 83

4261 Advantages of self-contained oil-filled cables 85 4262 Advantages of oil-filled cables 85 4263 Oil for cables 85

427 Gas-pressure cables 86 427 1 External gas-pressure cables 86 4272 Internal gas-pressure cables 86

428 Compressed gas insulated cables (GIC) 87 429 Advantages of GIC over oil-filled cables 88 430 Cross-linked polyethylene (XLPE) cables 89 4 3 Power cable installation 89

6

xii Co tents

5 Line Insulators and Supports 93 - 122

5 Introduction 93 5 Types of insulator 95

521 Pin type insulator 95 522 Suspension insulators 96 523 Strain or tension insulators 97

5 V -strings 98 5 Insulator materials 98

541 Polymer insulator 99 5~ Voltage distribution and string efficiency 99

551 Alternative method 101 5 t Improving voltage distribution 103 5 Selection of insulation 112 5 t Line supports 113 5 ~ Wood poles 114 5 m Concrete poles 114 5 I I Steel poles 115 5 1l2 Supporting towers 115

5121 Self-supporting towers 115 5 122 Guyed or stayed towers 115

5 0 Vibration of conductors 117 513 I Resonant vibration 117 513 2 Galloping 1J8 5133 Dancing and steel-jump 118

51+ Effects of vibration on the transmission line 1J8 515 Prevention of vibration 119

5151 Armour rods 119 5152 Stockbridge damper 119

51 5 Spacing of conductors 120

Sa and Tension 123 - 150 61 Introduction 123 62 Sag and tension 123 63 Parabolic method 124 64 Catenary method 125 65 Accuracy of results 1)8 66 Loading on conductors 128 67 Conductor clearance from ground 1J I 68 Erection sag and tension 132

681 Factors affecting the sag 133 69 Spans of unequal length 137 61 Sag and tension charts 138 61 Supports at unequal leves 139 61 The sag template 144 61 = Preparation of the sag template 145 61 c Method of using the template 146 6 1 Economic span length 147

7

8

Contents xiii

Line Parameters 151- 212 7 J Introduction 151 77 Line inductance 151 7 3 Inductance of a conductor 152

731 Internal inductance 152 732 External inductance 154

74 Flux linkages in a group of conductors 155 75 Inductance of a two-wire line 157 76 Inductance of symmetrical three-phase line 159 77 Inductance of unsymmetrical three-phase line 160 78 Method of geometric mean distances 163 79 Two-wire line 165 710 Symmetrical three-phase line 165 7 11 Inductance of unsymmetrical three-phase line 166 7 12 Inductance of double-circuit single-phase line 169 7 13 Inductance of double-circuit three-phase lines 170 714 Special cases of double-circuit lines 172 7 15 Inductance of bundled conductor lines 174 716 Line capacitance 178 7 17 Electric field of a long straight conductor 178 718 System of conductors 179 719 Capacitance of two-wire line 180 720 Capacitance of the symmetrical three-phase line 182 721 Capacitance of an unsymmetrical three-phase transposed line 183 722 Capacitance of a three-phase single-circuit untransposed line 186 723 Charging current 187 724 Capacitance by GMD method 188 725 Capacitance of double-circuit three-phase line 189 726 Effect of earth on the line capacitance 190 727 Effect of earth on capacitance of single-circuit three-phase line

with transposition 193 728 Capacitance of bundled conductor lines 195 7 29 Shunt conductance 198 730 Interference between power and communication lines 198 7 31 Electromagnetic effect 198 732 Electrostatic effect 199

Per Unit Representation 213 - 237

81 Introduction 213 82 Change of base 2 J 6 83 Per unit impedance of a transformer 216 84 Per unit quantities in three-phase systems 219 85 Selection of base values 221 86 Base quantities in terms of kV and MVA 221 87 Per unit load impedance 222

Electrical Power System

Publisher CBS Publications ISBN 9788123914480 Author Ashfaq Hussain

Type the URL httpwwwkopykitabcomproduct10371

Get this eBook

x Contents

2 Supply Systems 16 - 35

2 I Introduction 16 22 Basic structure of an AC power system 16 23 Distribution voltage level 16 24 Subtransmiss ion level 17 25 Transmi ssion level 17 26 Layout of a power supply network 17 27 System interconnection 18 28 System voltage and transmission efficIency 19 29 Working voltage 20 210 Choice of the next high voltage 20 2 I I Standardization of transmission voltages 21 2 12 Classification of lines 21 213 Comparison of conductor costs in various systems 22

2 13 I Criterion of equal maximum voltage to earth 23 2132 Criterion of equal maximum voltage between line

conductors 27

3 Conductors 36 - 54

31 Introduction 36 32 Types of conductors 37

321 Hard-drawn copper conductors 37 322 Cadmium copper conductor 37 323 Steel-cored copper conductor (SCC) 38 324 Copperweld conductor 38 325 Hard-drawn aluminium conductor or all -aluminium

conductor (AAC) 38 326 Aluminium conductor steel reinforced (ACSR) 38 327 Smooth tyengtdy ACSR conductor 39 328 Expandeq ACSR conductor 40 32Y All-aluminium allay conductor (AAAC) 40 3210 ACAR conductor 40 321 I Alumoweld conductor 41 3212 Phosphor-bronze conductor 41 32 13 Galvanized stee l conductt)r 41

33 Resistance 41 34 Skin effect 42

35 Equivalent coppe r section 43 36 Kelvins economy law 43 37 Modified Kelvins law 44 38 Graphical representation 45 39 Economic current density 46 310 Determination of losses 49 311 Limitations of Kelvin s law 52

Contents xi

4 Power Cables 55-92~

41 Introduction 55 42 Cable construction 56 43 Conductors 56 44 Insulation 57 45 Sheath 58 46 Protective covering 58 47 Belted cable 59 48 Screened cable 59 49 Cable impregnation 60 410 Non-drained cables 60 4 II Dielectric stress 60 4 12 Grading of cables 64 413 Cable capacitance 70 414 Charging current or capacitive current 70 415 Capacitances in a three-core belted cable 70 4 16 Measurement of Cc and Cs 72 4 17 Insulation resistance 74 4 18 Dielectric loss 75

4181 Conductivity of insulation 75 418 2 Dielectric hysteresis or dielectric absorption 75 4183 Corona or gaseous ionization in cables 76 4184 Dielectric power loss 76

419 Stress distribution in a HYDC cable 78 420 Skin effect 79 421 Proximity effect 79 422 Current rating of cables 79

4221 Normal or safe current carrying capacity 79 422 2 Over current rating 8 4223 Short-circuit rating 82

4 23 Thermal breakdown 82 424 Soil thermal resistivity 82 425 Extra high voltage cables 82 4 26 Oil-filled cables 83

4261 Advantages of self-contained oil-filled cables 85 4262 Advantages of oil-filled cables 85 4263 Oil for cables 85

427 Gas-pressure cables 86 427 1 External gas-pressure cables 86 4272 Internal gas-pressure cables 86

428 Compressed gas insulated cables (GIC) 87 429 Advantages of GIC over oil-filled cables 88 430 Cross-linked polyethylene (XLPE) cables 89 4 3 Power cable installation 89

6

xii Co tents

5 Line Insulators and Supports 93 - 122

5 Introduction 93 5 Types of insulator 95

521 Pin type insulator 95 522 Suspension insulators 96 523 Strain or tension insulators 97

5 V -strings 98 5 Insulator materials 98

541 Polymer insulator 99 5~ Voltage distribution and string efficiency 99

551 Alternative method 101 5 t Improving voltage distribution 103 5 Selection of insulation 112 5 t Line supports 113 5 ~ Wood poles 114 5 m Concrete poles 114 5 I I Steel poles 115 5 1l2 Supporting towers 115

5121 Self-supporting towers 115 5 122 Guyed or stayed towers 115

5 0 Vibration of conductors 117 513 I Resonant vibration 117 513 2 Galloping 1J8 5133 Dancing and steel-jump 118

51+ Effects of vibration on the transmission line 1J8 515 Prevention of vibration 119

5151 Armour rods 119 5152 Stockbridge damper 119

51 5 Spacing of conductors 120

Sa and Tension 123 - 150 61 Introduction 123 62 Sag and tension 123 63 Parabolic method 124 64 Catenary method 125 65 Accuracy of results 1)8 66 Loading on conductors 128 67 Conductor clearance from ground 1J I 68 Erection sag and tension 132

681 Factors affecting the sag 133 69 Spans of unequal length 137 61 Sag and tension charts 138 61 Supports at unequal leves 139 61 The sag template 144 61 = Preparation of the sag template 145 61 c Method of using the template 146 6 1 Economic span length 147

7

8

Contents xiii

Line Parameters 151- 212 7 J Introduction 151 77 Line inductance 151 7 3 Inductance of a conductor 152

731 Internal inductance 152 732 External inductance 154

74 Flux linkages in a group of conductors 155 75 Inductance of a two-wire line 157 76 Inductance of symmetrical three-phase line 159 77 Inductance of unsymmetrical three-phase line 160 78 Method of geometric mean distances 163 79 Two-wire line 165 710 Symmetrical three-phase line 165 7 11 Inductance of unsymmetrical three-phase line 166 7 12 Inductance of double-circuit single-phase line 169 7 13 Inductance of double-circuit three-phase lines 170 714 Special cases of double-circuit lines 172 7 15 Inductance of bundled conductor lines 174 716 Line capacitance 178 7 17 Electric field of a long straight conductor 178 718 System of conductors 179 719 Capacitance of two-wire line 180 720 Capacitance of the symmetrical three-phase line 182 721 Capacitance of an unsymmetrical three-phase transposed line 183 722 Capacitance of a three-phase single-circuit untransposed line 186 723 Charging current 187 724 Capacitance by GMD method 188 725 Capacitance of double-circuit three-phase line 189 726 Effect of earth on the line capacitance 190 727 Effect of earth on capacitance of single-circuit three-phase line

with transposition 193 728 Capacitance of bundled conductor lines 195 7 29 Shunt conductance 198 730 Interference between power and communication lines 198 7 31 Electromagnetic effect 198 732 Electrostatic effect 199

Per Unit Representation 213 - 237

81 Introduction 213 82 Change of base 2 J 6 83 Per unit impedance of a transformer 216 84 Per unit quantities in three-phase systems 219 85 Selection of base values 221 86 Base quantities in terms of kV and MVA 221 87 Per unit load impedance 222

Electrical Power System

Publisher CBS Publications ISBN 9788123914480 Author Ashfaq Hussain

Type the URL httpwwwkopykitabcomproduct10371

Get this eBook

Contents xi

4 Power Cables 55-92~

41 Introduction 55 42 Cable construction 56 43 Conductors 56 44 Insulation 57 45 Sheath 58 46 Protective covering 58 47 Belted cable 59 48 Screened cable 59 49 Cable impregnation 60 410 Non-drained cables 60 4 II Dielectric stress 60 4 12 Grading of cables 64 413 Cable capacitance 70 414 Charging current or capacitive current 70 415 Capacitances in a three-core belted cable 70 4 16 Measurement of Cc and Cs 72 4 17 Insulation resistance 74 4 18 Dielectric loss 75

4181 Conductivity of insulation 75 418 2 Dielectric hysteresis or dielectric absorption 75 4183 Corona or gaseous ionization in cables 76 4184 Dielectric power loss 76

419 Stress distribution in a HYDC cable 78 420 Skin effect 79 421 Proximity effect 79 422 Current rating of cables 79

4221 Normal or safe current carrying capacity 79 422 2 Over current rating 8 4223 Short-circuit rating 82

4 23 Thermal breakdown 82 424 Soil thermal resistivity 82 425 Extra high voltage cables 82 4 26 Oil-filled cables 83

4261 Advantages of self-contained oil-filled cables 85 4262 Advantages of oil-filled cables 85 4263 Oil for cables 85

427 Gas-pressure cables 86 427 1 External gas-pressure cables 86 4272 Internal gas-pressure cables 86

428 Compressed gas insulated cables (GIC) 87 429 Advantages of GIC over oil-filled cables 88 430 Cross-linked polyethylene (XLPE) cables 89 4 3 Power cable installation 89

6

xii Co tents

5 Line Insulators and Supports 93 - 122

5 Introduction 93 5 Types of insulator 95

521 Pin type insulator 95 522 Suspension insulators 96 523 Strain or tension insulators 97

5 V -strings 98 5 Insulator materials 98

541 Polymer insulator 99 5~ Voltage distribution and string efficiency 99

551 Alternative method 101 5 t Improving voltage distribution 103 5 Selection of insulation 112 5 t Line supports 113 5 ~ Wood poles 114 5 m Concrete poles 114 5 I I Steel poles 115 5 1l2 Supporting towers 115

5121 Self-supporting towers 115 5 122 Guyed or stayed towers 115

5 0 Vibration of conductors 117 513 I Resonant vibration 117 513 2 Galloping 1J8 5133 Dancing and steel-jump 118

51+ Effects of vibration on the transmission line 1J8 515 Prevention of vibration 119

5151 Armour rods 119 5152 Stockbridge damper 119

51 5 Spacing of conductors 120

Sa and Tension 123 - 150 61 Introduction 123 62 Sag and tension 123 63 Parabolic method 124 64 Catenary method 125 65 Accuracy of results 1)8 66 Loading on conductors 128 67 Conductor clearance from ground 1J I 68 Erection sag and tension 132

681 Factors affecting the sag 133 69 Spans of unequal length 137 61 Sag and tension charts 138 61 Supports at unequal leves 139 61 The sag template 144 61 = Preparation of the sag template 145 61 c Method of using the template 146 6 1 Economic span length 147

7

8

Contents xiii

Line Parameters 151- 212 7 J Introduction 151 77 Line inductance 151 7 3 Inductance of a conductor 152

731 Internal inductance 152 732 External inductance 154

74 Flux linkages in a group of conductors 155 75 Inductance of a two-wire line 157 76 Inductance of symmetrical three-phase line 159 77 Inductance of unsymmetrical three-phase line 160 78 Method of geometric mean distances 163 79 Two-wire line 165 710 Symmetrical three-phase line 165 7 11 Inductance of unsymmetrical three-phase line 166 7 12 Inductance of double-circuit single-phase line 169 7 13 Inductance of double-circuit three-phase lines 170 714 Special cases of double-circuit lines 172 7 15 Inductance of bundled conductor lines 174 716 Line capacitance 178 7 17 Electric field of a long straight conductor 178 718 System of conductors 179 719 Capacitance of two-wire line 180 720 Capacitance of the symmetrical three-phase line 182 721 Capacitance of an unsymmetrical three-phase transposed line 183 722 Capacitance of a three-phase single-circuit untransposed line 186 723 Charging current 187 724 Capacitance by GMD method 188 725 Capacitance of double-circuit three-phase line 189 726 Effect of earth on the line capacitance 190 727 Effect of earth on capacitance of single-circuit three-phase line

with transposition 193 728 Capacitance of bundled conductor lines 195 7 29 Shunt conductance 198 730 Interference between power and communication lines 198 7 31 Electromagnetic effect 198 732 Electrostatic effect 199

Per Unit Representation 213 - 237

81 Introduction 213 82 Change of base 2 J 6 83 Per unit impedance of a transformer 216 84 Per unit quantities in three-phase systems 219 85 Selection of base values 221 86 Base quantities in terms of kV and MVA 221 87 Per unit load impedance 222

Electrical Power System

Publisher CBS Publications ISBN 9788123914480 Author Ashfaq Hussain

Type the URL httpwwwkopykitabcomproduct10371

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6

xii Co tents

5 Line Insulators and Supports 93 - 122

5 Introduction 93 5 Types of insulator 95

521 Pin type insulator 95 522 Suspension insulators 96 523 Strain or tension insulators 97

5 V -strings 98 5 Insulator materials 98

541 Polymer insulator 99 5~ Voltage distribution and string efficiency 99

551 Alternative method 101 5 t Improving voltage distribution 103 5 Selection of insulation 112 5 t Line supports 113 5 ~ Wood poles 114 5 m Concrete poles 114 5 I I Steel poles 115 5 1l2 Supporting towers 115

5121 Self-supporting towers 115 5 122 Guyed or stayed towers 115

5 0 Vibration of conductors 117 513 I Resonant vibration 117 513 2 Galloping 1J8 5133 Dancing and steel-jump 118

51+ Effects of vibration on the transmission line 1J8 515 Prevention of vibration 119

5151 Armour rods 119 5152 Stockbridge damper 119

51 5 Spacing of conductors 120

Sa and Tension 123 - 150 61 Introduction 123 62 Sag and tension 123 63 Parabolic method 124 64 Catenary method 125 65 Accuracy of results 1)8 66 Loading on conductors 128 67 Conductor clearance from ground 1J I 68 Erection sag and tension 132

681 Factors affecting the sag 133 69 Spans of unequal length 137 61 Sag and tension charts 138 61 Supports at unequal leves 139 61 The sag template 144 61 = Preparation of the sag template 145 61 c Method of using the template 146 6 1 Economic span length 147

7

8

Contents xiii

Line Parameters 151- 212 7 J Introduction 151 77 Line inductance 151 7 3 Inductance of a conductor 152

731 Internal inductance 152 732 External inductance 154

74 Flux linkages in a group of conductors 155 75 Inductance of a two-wire line 157 76 Inductance of symmetrical three-phase line 159 77 Inductance of unsymmetrical three-phase line 160 78 Method of geometric mean distances 163 79 Two-wire line 165 710 Symmetrical three-phase line 165 7 11 Inductance of unsymmetrical three-phase line 166 7 12 Inductance of double-circuit single-phase line 169 7 13 Inductance of double-circuit three-phase lines 170 714 Special cases of double-circuit lines 172 7 15 Inductance of bundled conductor lines 174 716 Line capacitance 178 7 17 Electric field of a long straight conductor 178 718 System of conductors 179 719 Capacitance of two-wire line 180 720 Capacitance of the symmetrical three-phase line 182 721 Capacitance of an unsymmetrical three-phase transposed line 183 722 Capacitance of a three-phase single-circuit untransposed line 186 723 Charging current 187 724 Capacitance by GMD method 188 725 Capacitance of double-circuit three-phase line 189 726 Effect of earth on the line capacitance 190 727 Effect of earth on capacitance of single-circuit three-phase line

with transposition 193 728 Capacitance of bundled conductor lines 195 7 29 Shunt conductance 198 730 Interference between power and communication lines 198 7 31 Electromagnetic effect 198 732 Electrostatic effect 199

Per Unit Representation 213 - 237

81 Introduction 213 82 Change of base 2 J 6 83 Per unit impedance of a transformer 216 84 Per unit quantities in three-phase systems 219 85 Selection of base values 221 86 Base quantities in terms of kV and MVA 221 87 Per unit load impedance 222

Electrical Power System

Publisher CBS Publications ISBN 9788123914480 Author Ashfaq Hussain

Type the URL httpwwwkopykitabcomproduct10371

Get this eBook

7

8

Contents xiii

Line Parameters 151- 212 7 J Introduction 151 77 Line inductance 151 7 3 Inductance of a conductor 152

731 Internal inductance 152 732 External inductance 154

74 Flux linkages in a group of conductors 155 75 Inductance of a two-wire line 157 76 Inductance of symmetrical three-phase line 159 77 Inductance of unsymmetrical three-phase line 160 78 Method of geometric mean distances 163 79 Two-wire line 165 710 Symmetrical three-phase line 165 7 11 Inductance of unsymmetrical three-phase line 166 7 12 Inductance of double-circuit single-phase line 169 7 13 Inductance of double-circuit three-phase lines 170 714 Special cases of double-circuit lines 172 7 15 Inductance of bundled conductor lines 174 716 Line capacitance 178 7 17 Electric field of a long straight conductor 178 718 System of conductors 179 719 Capacitance of two-wire line 180 720 Capacitance of the symmetrical three-phase line 182 721 Capacitance of an unsymmetrical three-phase transposed line 183 722 Capacitance of a three-phase single-circuit untransposed line 186 723 Charging current 187 724 Capacitance by GMD method 188 725 Capacitance of double-circuit three-phase line 189 726 Effect of earth on the line capacitance 190 727 Effect of earth on capacitance of single-circuit three-phase line

with transposition 193 728 Capacitance of bundled conductor lines 195 7 29 Shunt conductance 198 730 Interference between power and communication lines 198 7 31 Electromagnetic effect 198 732 Electrostatic effect 199

Per Unit Representation 213 - 237

81 Introduction 213 82 Change of base 2 J 6 83 Per unit impedance of a transformer 216 84 Per unit quantities in three-phase systems 219 85 Selection of base values 221 86 Base quantities in terms of kV and MVA 221 87 Per unit load impedance 222

Electrical Power System

Publisher CBS Publications ISBN 9788123914480 Author Ashfaq Hussain

Type the URL httpwwwkopykitabcomproduct10371

Get this eBook

Electrical Power System

Publisher CBS Publications ISBN 9788123914480 Author Ashfaq Hussain

Type the URL httpwwwkopykitabcomproduct10371

Get this eBook