Analysis and Design of Low-Power Systems

Transcription

1 Analysis and Design of Low-Power Systems An Engineer s Field Guide Ismail Kasikci

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3 Ismail Kasikci Analysis and Design of Low-Voltage Power-Systems

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5 Analysis and Design of Low-Power Systems An Engineer s Field Guide Ismail Kasikci

6 Dr Ismail Kasikci Ahornstraûe 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 < 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

7 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 Physical Basis Cores Windings Types AC Transformers Design Principle of Operation No-Load Voltage Voltage and Current Transformation Transformer Loading Three-Phase Transformers Design Winding Connections Connection Symbols Parallel Connection of Transformers 29

8 VI Contents 47 Special-Purpose Transformers Current Transformers Voltage Transformers Autotransformers Efficiency of Transformers Protection of Transformers Selection of Transformers Rules of Thumb for Calculating Short Circuit Currents on the Low-Voltage Side Examples for Transformers Example 1: Calculation of the Initial Symmetrical Short Circuit Current for a Transformer Example 2: Calculation of Equalizing Currents Example 3: Economic Efficiency of Transformers Example 4: Calculation of Efficiency Over a Year Example 5: Calculation of Efficiency 43 5 Asynchronous Motors (ASM) Designs and Types Principle of Operation (No-Load) Typical Speed-Torque Characteristics Properties Characterizing Asynchronous Motors Rotor Frequency Torque Slip Gear System Startup of Asynchronous Motors Direct Switch-On Star Delta Startup Speed Adjustment Speed Control by the Slip Speed Control by Frequency Speed Control by Pole Changing Soft Starters Motor Operating Modes Project Planning of Drives Example 1: Calculation With SIKOSTART Example 2: Calculation of Overload and Starting Conditions Example 3: Calculation of Motor Data Example 4: Calculation of the Belt Pulley Diameter and Motor Power Example 5: Dimensioning of a Motor 77 6 Emergency Generators Generator-Specific Limiting Operational Values 83

9 Contents VII 62 Planning a Standby Generator Example: Calculation of Standby Generator Power 85 7 Equipment for Overcurrent Protection Electric Arc Electric Arc Characteristic DC Cut-Off AC Cut-Off Transient Voltage Low-Voltage Switchgear Characteristic Parameters Main or Load Switches Motor Protective Switches Contactors and Motor Starters Circuit Breakers RCDs (Residual Current Protective Devices) Main Protective Equipment Meter mounting boards with main protective switch Fuses Power Circuit Breakers Load Interrupter Switches Disconnect Switches Fuse Links List of Components Selectivity and Backup Protection Selectivity Backup Protection Switchgear Combinations Type-Tested Switchgear Combinations (TSC) Partially Type-Tested Switchgear Combinations (PTSC) Proof of Short Circuit Strength Proof of Compliance With Upper Temperature Limits in Partially Type-Tested Switchgear Combinations Differentiation of Power Losses Checklist Notes on Project Planning Example: Computer Evaluation of Temperature Rise Protection Against Electric Shock Voltage Ranges Protection by Cut-Off or Warning Messages TN-Systems TT-Systems 148

10 VIII Contents 1023 IT Systems Summary of cut-off times and loop resistances Example 1: Checking Protective Measures Example 2: Determination of Rated Fuse Current Example 3: Calculation of Maximum Conductor Length Example 4: Rated current for a TT System Example 5: Cut-Off Condition for an IT System Example 6: Protective Measure for Connection Line to a House Example 7: Protective Measure for a TT System Current Carrying Capacity of Conductors and Cables Terms and Definitions Overload Protection Short Circuit Protection Designation of Conductors Designation of Cables Current Carrying Capacity Loading Capacity Under Normal Operating Conditions Loading Capacity Under Fault Conditions Installation Types and Load Values for Lines and Cables Current Carrying Capacity of Heavy Current Cables and Correction Factors for Underground and Overhead Installation Examples of Current Carrying Capacity Example 1: Checking Current Carrying Capacity Example 2: Checking Current Carrying Capacity Example 3: Protection of Cables in Parallel Example 4: Connection of a Three-Phase Cable Example 5: Apartment Building Without Electrical Water Heating Examples for the Calculation of Overcurrents Example 1: Determination of Overcurrents and Short Circuit Currents Example 2: Overload Protection Example 3: Short Circuit Strength of a Conductor Example 4: Checking Protective Measures for Circuit Breakers Calculation of Short Circuit Currents in Three-Phase Networks The Equivalent Voltage Source Method Single-Pole Short Circuits to Ground Calculation of Loop Impedance Three-Pole Short Circuits Calculation of Resistance Values for Operational Equipment Network Feeders Synchronous Machines Consideration of Motors Overland Lines, Cables and Lines 224

11 Contents IX 1225 Transformers Impedance Corrections Short Circuit Currents for Three-Pole Short Circuits Peak Short Circuit Current Symmetrical Breaking Current Steady State Short Circuit Current Thermal and Dynamic Short Circuit Strength Examples for the Calculation of Short Circuit Currents Example 1: Calculation of the Short Circuit Current in a DC System Example 2: Calculation of Short Circuit Currents in a Building Electrical System Example 3: Dimensioning of an Exit Cable Example 4: Calculation of Short Circuit Currents with Zero-Sequence Resistances Example 5: Complex Calculation of Short Circuit Currents Example 6: Calculation With Effective Power and Reactive Power Example 7: Complete Calculation for a System Example 8: Calculation of Short Circuit Currents With Impedance Corrections Voltage Drop Calculations Voltage Regulation Permissible Voltage Drop in Accordance With the Technical Conditions for Connection Permissible Voltage Drop in Accordance With Electrical Installations in Buildings Voltage Drops in Load Systems Voltage Drops in Accordance With IEC Parameters for the Maximum Line Length Summary of Characteristic Parameters Lengths of Conductors With a Source Impedance Examples for the Calculation of Voltage Drops Example 1: Calculation of Voltage Drop for a DC System Example 2: Calculation of Voltage Drop for an AC System Voltage Drop for a Three-Phase System Example 4: Calculation of Voltage Drop for a Distributor Calculation of Cross-Section According to Voltage Drop Example 6: Calculation of Voltage Drop for an industrial plant Example 7: Calculation of voltage drop for an electrical outlet Example 8: Calculation of Voltage Drop for a Hot Water Storage Unit Example 9: Calculation of Voltage Drop for a Pump Facility Lighting Systems Interior Lighting Types of Lighting 280

12 X Contents 1421 Normal Lighting Normal Workplace-Oriented Lighting Localized Lighting Technical Requirements for Lighting Selection and Installation of Operational Equipment Lighting Circuits for Special Rooms and Systems Lighting Calculations Planning of Lighting with Data Blocks System Power Distribution of Luminous Intensity Luminous Flux Distribution Efficiencies Spacing Between Lighting Elements Number of fluorescent lamps in a Room Illuminance Distribution Curves Maximum Number of Fluorescent Lamps on Switches Maximum Number of Discharge Lamps Per Circuit Breaker Mark of Origin Standard Values for Planning Lighting Systems Economic Analysis and Costs of Lighting Procedure for Project Planning Exterior Lighting Low-Voltage Halogen Lamps Safety and Standby Lighting Terms and Definitions Circuits Structural Types for Groups of People Planning and Configuring of Emergency-Symbol and Safety Lighting Power Supply Notes on Installation Testing During Operation Battery Systems Central Battery Systems Grouped Battery Systems Single Battery Systems Example: Dimensioning of Safety and Standby Lighting Compensation for Reactive Power Terms and Definitions Effect of Reactive Power Compensation for Transformers Compensation for Asynchronous Motors Compensation for Discharge Lamps c/k Value 323

13 Contents XI 157 Resonant Circuits Harmonics and Voltage Quality Compensation With Non-Choked Capacitors Inductor-Capacitor Units Series Resonant Filter Circuits Static Compensation for Reactive Power Examples of Compensation for Reactive Power Example 1: Determination of Capacitive Power Example 2: Capacitive Power With k Factor Example 3: Determination of Cable Cross-Section Example 4: Calculation of the c/k Value Lightning Protection Systems Lightning Protection Class Exterior Lightning Protection Air Terminal Down Conductors Grounding Systems Example 1: Calculation of Grounding Resistances Example 2: Minimum Lengths of Grounding Electrodes Exposure Distances in the Wall Area Grounding of Antenna Systems Examples of Installations Interior Lightning Protection The EMC Lightning Protection Zone Concept Planning Data for Lightning Protection Systems Using the CD-ROM Use of CAD Systems SIKOSTART: Dimensioning and Calculation of Startup Time for a Motor TXI: Calculations for Lighting Systems TRABTECH-Select: Planning Software for Overvoltage Protection Concepts MODLCON (MODL Power Conditioning): Calculation of Compensating Systems for Reactive Currents KUBS plus: Short Circuit Calculations NEPLAN: Planning and information system for electrical networks Aids for Installation 379 Bibliography 381 Index 383

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15 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