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BASIC ELECTRICAL ENGINEERING This page intentionally left blank BASIC ELECTRICAL ENGINEERING FOURTH EDITION C. L. Wadhwa FormePrlryo fessor DepartmoefEn ltec tricEanlg ineering DelChoil leogfEe n gineeriDnegl,h i FormeDearnl y FaculotyfT echnology UniveorfsD ietyl hDie,l hi PUBLISHING FOR ONE WORLD NEW AGE INTERNATIONAL (P) LIMITED, PUBLISHERS • • • • • • • • • New Delhi Bangalore Chennai Cochin Guwahati Hydcrnbad Jalandhar uKs olkata Lucknow Mumbai Ranchi Visi[ ac www.newagepublishers.com Copyri©g h2t0072,0 062,0 04N ewA geI nternati(oPnL)a tld .P,u blishers PublishbeydN ewA geI nternat(iPo)nL atld .P,u blishers Allr ighrtess erved. No parotf theibso omka yb er eproduicnea dn yfo rm,b yp hottoastm ,i crofilxme,r ogrhayp, ora nyo themre an,so ri ncorporaitnetdao n yi nformatiroent riesvyasll eeml,e clroonri c mechanicwailt,h outth ew rittpeenr missiooftn h ep ublishAelrli. n quirsiheosu lbde emailteodr [email protected] ISBN( 13)9 7:8 -81-224-2947-3 PUBLISHFIONROG N EW ORLD NEW AGE INTERNATIONA(LP L)I MITEDP,U BLISHERS 4835/24,AnRsoaardiD, a ryagaNnejw, D elh-i1 10002 Visiutsa tw ww.newagepublishers.com To My mothewrh,o t aughmte howt oh oldp eni nm y littflien gers. My fathewrh,o t aughmte modestayn dt olerance. My wifea, s ymboolf m utuatlr usatn dm utuarle spect. My daughtaenrd s onw,h oe xhibiat ehdi ghd egreoefp atience. My studenwthso,m adem e leartnh es ubject. TheA lmightwyh,o h asc reatseudc ha beautiwfourll d. This page intentionally left blank PREFACE TO THE FOURTH EDITION In the fourth edition of Basic Electrical Engineering, two more chapters have been added. Chapter i on DC circuits explains the International System of Units and gives clear concepts of electrical circuits, current, voltage or potential, resistance, power and energy. Also, Ohm's law and Kirchoffs laws have been explained with a solution of series and parallel circuits using these laws. Chapter ii on electromagnetic induction explains Faraday's laws of electromagnetic induction and Lenz's law. Laws of electromagnetic forces, dynamically and statically induced e.m.f.'s have also been explained. Further, concepts of mutual and self-inductances, and hysteresis losses and eddy current losses have been discussed. Under AC circuits, in chapter 1, the concepts ofleakage flux, fringing flux, magnetostatic potential, m.m.f. and reluctance have been included. With these additions, the utility of this book has been greatly enhanced. Any constructive suggestion for further improvement of this book will be gratefully acknowledged. C.L. Wadhwa vii This page intentionally left blank PREFACE TO THE FIRST EDITION Electrical Engineering has been written as a core course for all engineering students viz. Electronics and Communication, Computer Engineering, Civil, Mechanical Engineering etc. With advancement in technologies in almost all spheres of engineering, it is becoming difficult to provide more than one slot for interdisciplinary courses. However, the author feels that no engineering can work without electric energy. The basic input to all engineering is the electric energy. A basic course on Electrical Engineering is almost essential for all engineering students. Keeping this compulsion in mind and also that this course will normally he offered at the first year level of engineering, the author has made modest effort to give in a concise form various features of Electrical Engineering starting from simple ac circuits to Network theorems, measuring instruments, transformers, various de and ac machines including stepper motor. Various physical phenomenon have been explained using simple language avoiding the rigorus of mathematics. Chapter I deals with the steady state analysis of a.c. series and parallel circuits and series and parallel resonance. Chapter II describes various network theorems, star-delta transformation and methods of mesh and nodal analysis for de networks. Balanced and unbalanced, three phase circuits have been analysed and methods of 3- phase power measurements have been discussed in Chapter III. Measuring instruments like, ammeter, voltmeter, wattmeter and energy meter have been described in chapter IV. Transformer is a very important electrical equipment. The construction, principle of operation, parameter calculations, efficiency and regulation of transformer have been discussed in chapter V. Chapter VI deals in types of de machines, their operation and characteristics, efficiency and speed control and application of these machines. Chapter VII deals into the construction, principle of operation and applications of three phase synchronous motors and stepper motor. Three phase induction motors form atmost 60 to 70% of the total load on power system. These motors have been discussed in chapter VIII including types, construction, principle of operation, methods of starting, torque-slip characteristic, application and single phasing operation. Single phase induction motors find wide application in Office and domestic appliances. Construction, principle of operation and application of these motors have been described in chapter IX. Power systems is the most capital intensive and the most complex system ever devel oped by man. Chapter gives in brief, various supply and distribution systems and suggests methods for improvement of power factor. X ix