Analysis and Design of Low-Power Systems An Engineer s Field Guide Ismail Kasikci
Ismail Kasikci Analysis and Design of Low-Voltage Power-Systems
Analysis and Design of Low-Power Systems An Engineer s Field Guide Ismail Kasikci
Dr Ismail Kasikci Ahornstraûe 55 69469 Weinheim Germany & This book was carefully produced Nevertheless, authors and publisher do not warrant the information contained therein to be free of errors Readers are advised to keep in mind that statements, data, illustrations, procedural details or other items may inadvertently be inaccurate Library of Congress Card No: applied for British Library Cataloguing-in-Publication Data: A catalogue record for this book isavailable from the British Library Bibliogr aphic information published by Die Deutsche Bibliothe k Die Deutsche Bibliothek lists this publication in the Deutsche Nationalbibliografie; detailed bibliographic data is available in the Internet at <http://dnbddbde> 2004 Wiley-VCH Verlag-GmbH & Co KGaA, Weinheim All rights reserved (including those of translation in other languages) No part of this book may be reproduced in any form by photoprinting, microfilm, or any other means nor transmitted or translated into a machine language without written permission from the publisher Registered names, trademarks, etc used in this book, even when not specifically marked as such, are not to be considered unprotected by law printed in the Federal Republic of Germany printed on acid-free paper Composition Kühn & Weyh, Freiburg Printing betz-druck GmbH, Darmstadt Bookbinding Litges & Dopf Buchbinderei GmbH, Heppenheim ISBN 3-527-30483-5
V Contents Foreword Symbols XIII XV Abbreviations XXI 1 Introduction 1 2 Planning and Project Management 3 21 Guidelines for the Remuneration of Architects and Engineers and Regulations for Contracting System Installations 3 22 Guidelines for Project Planning of Electrical Systems 4 3 Electrical Systems 7 31 Medium-Voltage Systems 7 32 Low-Voltage Systems 9 4 Transformers 15 41 Physical Basis 15 42 Cores 20 43 Windings 21 44 Types 21 45 AC Transformers 21 451 Design 21 452 Principle of Operation 22 453 No-Load Voltage 23 454 Voltage and Current Transformation 23 455 Transformer Loading 24 46 Three-Phase Transformers 26 461 Design 26 462 Winding Connections 27 463 Connection Symbols 28 464 Parallel Connection of Transformers 29
VI Contents 47 Special-Purpose Transformers 30 471 Current Transformers 30 472 Voltage Transformers 31 473 Autotransformers 32 48 Efficiency of Transformers 33 49 Protection of Transformers 33 410 Selection of Transformers 34 411 Rules of Thumb for Calculating Short Circuit Currents on the Low-Voltage Side 39 412 Examples for Transformers 40 4121 Example 1: Calculation of the Initial Symmetrical Short Circuit Current for a Transformer 40 4122 Example 2: Calculation of Equalizing Currents 41 4123 Example 3: Economic Efficiency of Transformers 41 4124 Example 4: Calculation of Efficiency Over a Year 42 4125 Example 5: Calculation of Efficiency 43 5 Asynchronous Motors (ASM) 45 51 Designs and Types 45 511 Principle of Operation (No-Load) 46 512 Typical Speed-Torque Characteristics 47 52 Properties Characterizing Asynchronous Motors 48 521 Rotor Frequency 48 522 Torque 49 523 Slip 49 524 Gear System 50 53 Startup of Asynchronous Motors 51 531 Direct Switch-On 51 532 Star Delta Startup 53 54 Speed Adjustment 57 541 Speed Control by the Slip 57 542 Speed Control by Frequency 57 543 Speed Control by Pole Changing 58 544 Soft Starters 62 545 Motor Operating Modes 62 55 Project Planning of Drives 72 551 Example 1: Calculation With SIKOSTART 72 552 Example 2: Calculation of Overload and Starting Conditions 75 553 Example 3: Calculation of Motor Data 76 554 Example 4: Calculation of the Belt Pulley Diameter and Motor Power 76 555 Example 5: Dimensioning of a Motor 77 6 Emergency Generators 81 61 Generator-Specific Limiting Operational Values 83
Contents VII 62 Planning a Standby Generator 84 63 Example: Calculation of Standby Generator Power 85 7 Equipment for Overcurrent Protection 87 71 Electric Arc 87 711 Electric Arc Characteristic 88 712 DC Cut-Off 89 713 AC Cut-Off 90 714 Transient Voltage 92 72 Low-Voltage Switchgear 93 721 Characteristic Parameters 94 722 Main or Load Switches 94 723 Motor Protective Switches 95 724 Contactors and Motor Starters 96 725 Circuit Breakers 97 726 RCDs (Residual Current Protective Devices) 98 727 Main Protective Equipment 101 728 Meter mounting boards with main protective switch 105 729 Fuses 107 7210 Power Circuit Breakers 112 7211 Load Interrupter Switches 116 7212 Disconnect Switches 116 7213 Fuse Links 116 7214 List of Components 118 8 Selectivity and Backup Protection 119 81 Selectivity 119 82 Backup Protection 128 9 Switchgear Combinations 131 91 Type-Tested Switchgear Combinations (TSC) 131 92 Partially Type-Tested Switchgear Combinations (PTSC) 132 93 Proof of Short Circuit Strength 132 94 Proof of Compliance With Upper Temperature Limits in Partially Type-Tested Switchgear Combinations 133 95 Differentiation of Power Losses 134 96 Checklist 135 97 Notes on Project Planning 136 98 Example: Computer Evaluation of Temperature Rise 136 10 Protection Against Electric Shock 145 101 Voltage Ranges 145 102 Protection by Cut-Off or Warning Messages 146 1021 TN-Systems 146 1022 TT-Systems 148
VIII Contents 1023 IT Systems 151 1024 Summary of cut-off times and loop resistances 154 1025 Example 1: Checking Protective Measures 155 1026 Example 2: Determination of Rated Fuse Current 156 1027 Example 3: Calculation of Maximum Conductor Length 156 1028 Example 4: Rated current for a TT System 156 1029 Example 5: Cut-Off Condition for an IT System 157 10210 Example 6: Protective Measure for Connection Line to a House 157 10211 Example 7: Protective Measure for a TT System 159 11 Current Carrying Capacity of Conductors and Cables 161 111 Terms and Definitions 161 112 Overload Protection 162 113 Short Circuit Protection 163 1131 Designation of Conductors 167 1132 Designation of Cables 168 114 Current Carrying Capacity 169 1141 Loading Capacity Under Normal Operating Conditions 169 1142 Loading Capacity Under Fault Conditions 170 1143 Installation Types and Load Values for Lines and Cables 176 1144 Current Carrying Capacity of Heavy Current Cables and Correction Factors for Underground and Overhead Installation 184 115 Examples of Current Carrying Capacity 195 1151 Example 1: Checking Current Carrying Capacity 195 1152 Example 2: Checking Current Carrying Capacity 196 1153 Example 3: Protection of Cables in Parallel 197 1154 Example 4: Connection of a Three-Phase Cable 198 1155 Example 5: Apartment Building Without Electrical Water Heating 198 116 Examples for the Calculation of Overcurrents 203 1161 Example 1: Determination of Overcurrents and Short Circuit Currents 203 1162 Example 2: Overload Protection 205 1163 Example 3: Short Circuit Strength of a Conductor 206 1164 Example 4: Checking Protective Measures for Circuit Breakers 208 12 Calculation of Short Circuit Currents in Three-Phase Networks 213 121 The Equivalent Voltage Source Method 216 1211 Single-Pole Short Circuits to Ground 217 1212 Calculation of Loop Impedance 218 1213 Three-Pole Short Circuits 219 122 Calculation of Resistance Values for Operational Equipment 220 1221 Network Feeders 220 1222 Synchronous Machines 221 1223 Consideration of Motors 222 1224 Overland Lines, Cables and Lines 224
Contents IX 1225 Transformers 225 1226 Impedance Corrections 226 123 Short Circuit Currents for Three-Pole Short Circuits 228 1231 Peak Short Circuit Current 228 1232 Symmetrical Breaking Current 229 1233 Steady State Short Circuit Current 231 124 Thermal and Dynamic Short Circuit Strength 232 125 Examples for the Calculation of Short Circuit Currents 233 1251 Example 1: Calculation of the Short Circuit Current in a DC System 233 1252 Example 2: Calculation of Short Circuit Currents in a Building Electrical System 234 1253 Example 3: Dimensioning of an Exit Cable 236 1254 Example 4: Calculation of Short Circuit Currents with Zero-Sequence Resistances 237 1255 Example 5: Complex Calculation of Short Circuit Currents 239 1256 Example 6: Calculation With Effective Power and Reactive Power 242 1257 Example 7: Complete Calculation for a System 248 1258 Example 8: Calculation of Short Circuit Currents With Impedance Corrections 259 13 Voltage Drop Calculations 263 131 Voltage Regulation 263 1311 Permissible Voltage Drop in Accordance With the Technical Conditions for Connection 264 1312 Permissible Voltage Drop in Accordance With Electrical Installations in Buildings 264 1313 Voltage Drops in Load Systems 264 1314 Voltage Drops in Accordance With IEC 60 364 265 1315 Parameters for the Maximum Line Length 266 1316 Summary of Characteristic Parameters 268 1317 Lengths of Conductors With a Source Impedance 269 132 Examples for the Calculation of Voltage Drops 271 1321 Example 1: Calculation of Voltage Drop for a DC System 271 1322 Example 2: Calculation of Voltage Drop for an AC System 272 1323 Voltage Drop for a Three-Phase System 272 1324 Example 4: Calculation of Voltage Drop for a Distributor 274 1325 Calculation of Cross-Section According to Voltage Drop 275 1326 Example 6: Calculation of Voltage Drop for an industrial plant 276 1327 Example 7: Calculation of voltage drop for an electrical outlet 276 1328 Example 8: Calculation of Voltage Drop for a Hot Water Storage Unit 276 1329 Example 9: Calculation of Voltage Drop for a Pump Facility 277 14 Lighting Systems 279 141 Interior Lighting 279 142 Types of Lighting 280
X Contents 1421 Normal Lighting 280 1422 Normal Workplace-Oriented Lighting 281 1423 Localized Lighting 281 1424 Technical Requirements for Lighting 281 1425 Selection and Installation of Operational Equipment 282 1426 Lighting Circuits for Special Rooms and Systems 282 143 Lighting Calculations 284 144 Planning of Lighting with Data Blocks 285 1441 System Power 285 1442 Distribution of Luminous Intensity 286 1443 Luminous Flux Distribution 286 1444 Efficiencies 287 1445 Spacing Between Lighting Elements 287 1446 Number of fluorescent lamps in a Room 288 1447 Illuminance Distribution Curves 289 1448 Maximum Number of Fluorescent Lamps on Switches 289 1449 Maximum Number of Discharge Lamps Per Circuit Breaker 290 14410 Mark of Origin 290 14411 Standard Values for Planning Lighting Systems 291 14412 Economic Analysis and Costs of Lighting 291 145 Procedure for Project Planning 292 146 Exterior Lighting 296 147 Low-Voltage Halogen Lamps 296 148 Safety and Standby Lighting 298 1481 Terms and Definitions 298 1482 Circuits 298 1483 Structural Types for Groups of People 299 1484 Planning and Configuring of Emergency-Symbol and Safety Lighting 299 1485 Power Supply 303 1486 Notes on Installation 303 1487 Testing During Operation 304 149 Battery Systems 304 1491 Central Battery Systems 304 1492 Grouped Battery Systems 310 1493 Single Battery Systems 311 1494 Example: Dimensioning of Safety and Standby Lighting 315 15 Compensation for Reactive Power 317 151 Terms and Definitions 317 152 Effect of Reactive Power 321 153 Compensation for Transformers 321 154 Compensation for Asynchronous Motors 322 155 Compensation for Discharge Lamps 322 156 c/k Value 323
Contents XI 157 Resonant Circuits 323 158 Harmonics and Voltage Quality 325 1581 Compensation With Non-Choked Capacitors 326 1582 Inductor-Capacitor Units 328 1583 Series Resonant Filter Circuits 329 159 Static Compensation for Reactive Power 330 1510 Examples of Compensation for Reactive Power 333 15101 Example 1: Determination of Capacitive Power 333 15102 Example 2: Capacitive Power With k Factor 334 15103 Example 3: Determination of Cable Cross-Section 334 15104 Example 4: Calculation of the c/k Value 335 16 Lightning Protection Systems 337 161 Lightning Protection Class 339 162 Exterior Lightning Protection 340 1621 Air Terminal 340 1622 Down Conductors 344 1623 Grounding Systems 347 1624 Example 1: Calculation of Grounding Resistances 354 1625 Example 2: Minimum Lengths of Grounding Electrodes 354 1626 Exposure Distances in the Wall Area 355 1627 Grounding of Antenna Systems 357 1628 Examples of Installations 358 163 Interior Lightning Protection 359 1631 The EMC Lightning Protection Zone Concept 360 1632 Planning Data for Lightning Protection Systems 362 17 Using the CD-ROM 367 171 Use of CAD Systems 367 1711 SIKOSTART: Dimensioning and Calculation of Startup Time for a Motor 367 1712 TXI: Calculations for Lighting Systems 370 1713 TRABTECH-Select: Planning Software for Overvoltage Protection Concepts 371 1714 MODLCON (MODL Power Conditioning): Calculation of Compensating Systems for Reactive Currents 372 1715 KUBS plus: Short Circuit Calculations 372 1716 NEPLAN: Planning and information system for electrical networks 375 172 Aids for Installation 379 Bibliography 381 Index 383
XIII Foreword With each project, the planning engineer for electrical systems confronts the following questions: How can I design the electrical system? Which regulations must I observe? Which calculations must I perform? Which methods/cad can I use? Which protective measures must I consider? Which requirements and conditions apply for project planning? How can persons and animals be protected against electrical shock? Which operational components shall I select? Are there special problems with regard to planning? For calculation, dimensioning and evaluation of a system, in addition to extensive professional knowledge the planning engineer requires above all CAD experience and a knowledge of all relevant standards and regulations Due to the great number of standards and their revision in regular intervals and also due to their increasing international harmonization, maintaining this knowledge is becoming more and more difficult For this reason the present book, intended as a help for the planning engineer in the solution of problems in low voltage networks, also presents a detailed discussion of the current situation in regard to standards Following the theoretical part and the discussion of regulations and standards, a wide range of examples taken largely from practice is worked out fully The numerous tables and diagrams from which the planning values required for calculation can be taken make this book an indispensable reference Each topic is given its own treatment For the calculations required in project planning, the CAD programs included on the accompanying CD-ROM are certain to be of great use to the planning engineer The idea of developing an easy to use project planning aid for practical planning activities arose during my many years spent in the area of power supply, above all during my period of teaching at VDE, at the Technical Academy in Esslingen and at the Master Trade School in Heidelberg