ELECTRICAL ENERGY EFFICIENCY

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SUMPER BAGGINI

TECHNOLOGIES AND APPLICATIONS

ANDREAS SUMPER, BarcelonaTech (UPC), Institute for Energy Research (IREC), Spain ANGELO BAGGINI, University of Bergamo, Italy Improving electrical energy efficiency is becoming an essential area of sustainability development, backed by political initiatives to control and reduce energy demand. Now a major topic in industry and the electrical engineering research community, engineers have started to focus on analysis, diagnosis and possible solutions. Owing to the complexity and cross-disciplinary nature of electrical energy efficiency issues, the optimal solution is often multi-faceted with a critical solutions evaluation component to ensure cost effectiveness. This single-source reference brings a practical focus to the subject of electrical energy efficiency, providing detailed theory and real applications to enable engineers to find solutions for electroefficiency problems. It presents power supplier as well as electricity user perspectives and promotes routine implementation of good engineering practice. Key features include: a comprehensive overview of the different technologies involved in electroefficiency, outlining monitoring and control concepts and practical design techniques used in industrial applications; description of the current standards of electrical motors, with illustrative case studies showing how to achieve better design; up-to-date information on standarization, technologies, economic realities and energy efficiency indicators; coverage on the quality and efficiency of distribution systems (the impact on distribution systems and loads, and the calculation of power losses in distribution lines and in power transformers). With invaluable practical advice, this book is suited to practicing electrical engineers, design engineers, installation designers, M&E designers, and economic engineers. It equips maintenance and energy managers, planners, and infrastructure managers with the necessary knowledge to properly evaluate the wealth of electrical energy efficiency solutions for large investments. This reference also provides interesting reading material for energy researchers, policy makers, consultants, postgraduate engineering students and final year undergraduate engineering students.

ELECTRICAL ENERGY EFFICIENCY


ANDREAS SUMPER | ANGELO BAGGINI

ELECTRICAL ENERGY EFFICIENCY TECHNOLOGIES AND APPLICATIONS

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ELECTRICAL ENERGY EFFICIENCY TECHNOLOGIES AND APPLICATIONS

Andreas Sumper BarcelonaTech (UPC), Institute for Energy Research (IREC), Spain

Angelo Baggini University of Bergamo, Italy

A John Wiley & Sons, Ltd., Publication



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This edition first published 2012 C 2012 John Wiley & Sons, Ltd Registered office John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, United Kingdom For details of our global editorial offices, for customer services and for information about how to apply for permission to reuse the copyright material in this book please see our website at www.wiley.com. The right of the author to be identified as the author of this work has been asserted in accordance with the Copyright, Designs and Patents Act 1988. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by the UK Copyright, Designs and Patents Act 1988, without the prior permission of the publisher. Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic books. Designations used by companies to distinguish their products are often claimed as trademarks. All brand names and product names used in this book are trade names, service marks, trademarks or registered trademarks of their respective owners. The publisher is not associated with any product or vendor mentioned in this book. This publication is designed to provide accurate and authoritative information in regard to the subject matter covered. It is sold on the understanding that the publisher is not engaged in rendering professional services. If professional advice or other expert assistance is required, the services of a competent professional should be sought.

Library of Congress Cataloging-in-Publication Data Electrical energy efficiency : technologies and applications / Andreas Sumper and Angelo Baggini. p. cm. Includes bibliographical references and index. ISBN 978-0-470-97551-0 (hardback) 1. Electric power–Conservation–Standards. 2. Energy conservation–Standards. 3. Energy dissipation. 4. Electric power transmission–Reliability. I. Baggini, Angelo B. II. Sumper, Andreas. TJ163.3.E39 2012 621.31–dc23 2012000609 A catalogue record for this book is available from the British Library. Print ISBN: 9780470975510 Typeset in 10/12pt Times by Aptara Inc., New Delhi, India



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Contents List of Contributors Preface Foreword

xi xiii xv

1

Overview of Standardization of Energy Efficiency Franco Bua and Angelo Baggini

1

1.1

Standardization 1.1.1 ISO 1.1.2 IEC 1.1.3 CEN and CENELEC Further Readings

3 4 5 6 8

2

Cables and Lines Paola Pezzini and Andreas Sumper

9

2.1

Theory of Heat Transfer 2.1.1 Conduction 2.1.2 Convection 2.1.3 Radiation Current Rating of Cables Installed in Free Air Economic Aspects Calculation of the Current Rating: Total Costs 2.4.1 Evaluation of CJ Determination of Economic Conductor Sizes 2.5.1 Economic Current Range for Each Conductor in a Series of Sizes 2.5.2 Economic Conductor Size for a Given Load Summary References

10 10 10 11 12 15 16 16 18 18 18 19 19

3

Power Transformers Roman Targosz, Stefan Fassbinder and Angelo Baggini

21

3.1

Losses in Transformers 3.1.1 No-Load Losses 3.1.2 Load Losses

23 23 24

2.2 2.3 2.4 2.5

2.6



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3.1.3 Auxiliary Losses 3.1.4 Extra Losses due to Harmonics, Unbalance and Reactive Power Efficiency and Load Factor Losses and Cooling System Energy Efficiency Standards and Regulations 3.4.1 MEPS 3.4.2 Mandatory Labelling 3.4.3 Voluntary Programmes Life Cycle Costing 3.5.1 Life Cycle Cost of Transformers 3.5.2 Detailed Considerations Design, Material and Manufacturing 3.6.1 Core 3.6.2 Windings 3.6.3 Other Developments Case Study – Evaluation TOC of an Industrial Transformer 3.7.1 Method 3.7.2 Results References Further Readings Annex 3.A.1 Selected MEPS

24 25 30 31 32 37 37 37 39 40 44 47 47 52 54 54 55 56 59 59 60 60

4

Building Automation, Control and Management Systems Angelo Baggini and Annalisa Marra

71

4.1

Automation Functions for Energy Savings 4.1.1 Temperature Control 4.1.2 Lighting 4.1.3 Drives and Motors 4.1.4 Technical Alarms and Management 4.1.5 Remote Control Automation Systems 4.2.1 KNX Systems 4.2.2 Scada Systems Automation Device Own Consumption Basic Schemes 4.4.1 Heating and Cooling 4.4.2 Ventilation and Air Conditioning 4.4.3 Lighting 4.4.4 Sunscreens 4.4.5 Technical Building Management 4.4.6 Technical Installations in the Building The Estimate of Building Energy Performance 4.5.1 European Standard EN 15232 4.5.2 Comparison of Methods: Detailed Calculations and BAC Factors Further Readings

3.2 3.3 3.4

3.5

3.6

3.7

3.A

4.2

4.3 4.4

4.5

72 72 74 74 75 76 76 77 82 86 86 86 95 107 109 110 111 113 113 115 124



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5

Power Quality Phenomena and Indicators Andrei Cziker, Zbigniew Hanzelka and Ireana Wasiak

125

5.1

RMS Voltage Level 5.1.1 Sources 5.1.2 Effects on Energy Efficiency 5.1.3 Mitigation Methods Voltage Fluctuations 5.2.1 Disturbance Description 5.2.2 Sources of Voltage Fluctuations 5.2.3 Effects and Cost 5.2.4 Mitigation Methods Voltage and Current Unbalance 5.3.1 Disturbance Description 5.3.2 Sources 5.3.3 Effect and Cost 5.3.4 Mitigation Methods Voltage and Current Distortion 5.4.1 Disturbance Description 5.4.2 Sources 5.4.3 Effects and Cost 5.4.4 Mitigation Methods References Further Readings

126 127 128 130 132 132 134 135 138 138 139 140 140 143 145 145 146 147 153 162 162

6

On Site Generation and Microgrids Irena Wasiak and Zbigniew Hanzelka

165

6.1

Technologies of Distributed Energy Resources 6.1.1 Energy Sources 6.1.2 Energy Storage Impact of DG on Power Losses in Distribution Networks Microgrids 6.3.1 Concept 6.3.2 Energy Storage Applications 6.3.3 Management and Control 6.3.4 Power Quality and Reliability in Microgrids References Further Readings

166 166 170 175 178 178 180 182 184 186 187

7

Electric Motors Joris Lemmens and Wim Deprez

189

7.1

Losses in Electric Motors 7.1.1 Power Balance and Energy Efficiency 7.1.2 Loss Components Classification 7.1.3 Influence Factors Motor Efficiency Standards 7.2.1 Efficiency Classification Standards

190 191 193 195 199 199

5.2

5.3

5.4

6.2 6.3

7.2



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7.2.2 Efficiency Measurement Standards 7.2.3 Future Standard for Variable Speed Drives High Efficiency Motor Technology 7.3.1 Motor Materials 7.3.2 Motor Design 7.3.3 Motor Manufacturing References

200 207 208 210 218 224 226

8

Lighting Mircea Chindris and Antoni Sudria-Andreu

229

8.1

Energy and Lighting Systems 8.1.1 Energy Consumption in Lighting Systems 8.1.2 Energy Efficiency in Lighting Systems Regulations Technological Advances in Lighting Systems 8.3.1 Efficient Light Sources 8.3.2 Efficient Ballasts 8.3.3 Efficient Luminaries Energy Efficiency in Indoor Lighting Systems 8.4.1 Policy Actions to Support Energy Efficiency 8.4.2 Retrofit or Redesign? 8.4.3 Lighting Controls 8.4.4 Daylighting Energy Efficiency in Outdoor Lighting Systems 8.5.1 Efficient Lamps and Luminaires 8.5.2 Outdoor Lighting Controls Maintenance of Lighting Systems References Further Readings

230 230 231 233 234 234 239 241 242 242 245 247 251 252 253 256 259 260 261

9

Electrical Drives and Power Electronics Daniel Montesinos-Miracle, Joan Bergas-Jané and Edris Pouresmaeil

263

9.1

Control Methods for Induction Motors and PMSM 9.1.1 V/f Control 9.1.2 Vector Control 9.1.3 DTC Energy Optimal Control Methods 9.2.1 Converter Losses 9.2.2 Motor Losses 9.2.3 Energy Optimal Control Strategies Topology of the Variable Speed Drive 9.3.1 Input Stage 9.3.2 DC Bus 9.3.3 The Inverter New Trends on Power Semiconductors

266 266 271 272 274 275 276 276 276 277 278 279 280

7.3

8.2 8.3

8.4

8.5

8.6

9.2

9.3

9.4



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9.4.1 Modulation Techniques 9.4.2 Review of Different Modulation Methods References Further Readings

281 283 291 193

10

Industrial Heating Processes Mircea Chindris and Andreas Sumper

295

10.1 10.2

General Aspects Regarding Electroheating in Industry Main Electroheating Technologies 10.2.1 Resistance Heating 10.2.2 Infrared Heating 10.2.3 Induction Heating 10.2.4 Dielectric Heating 10.2.5 Arc Furnaces Specific Aspects Regarding the Increase of Energy Efficiency in Industrial Heating Processes 10.3.1 Replacement of Traditional Heating Technologies 10.3.2 Selection of the Most Suitable Electrotechnology 10.3.3 Increasing the Efficiency of the Existing Electroheating Equipment References Further Readings

298 302 302 309 314 318 325

10.3

326 327 329 330 333 334

11

Heat, Ventilation and Air Conditioning (HVAC) Roberto Villafáfila-Robles and Jaume Salom

335

11.1 11.2 11.3

Basic Concepts Environmental Thermal Comfort HVAC Systems 11.3.1 Energy Conversion 11.3.2 Energy Balance 11.3.3 Energy Efficiency Energy Measures in HVAC Systems 11.4.1 Final Service 11.4.2 Passive Methods 11.4.3 Conversion Device 11.4.4 Energy Sources References Further Readings

336 338 342 344 346 347 348 348 348 351 353 354 355

12

Data Centres Angelo Baggini and Franco Bua

357

12.1 12.2

Standards Consumption Profile 12.2.1 Energy Performance Index IT Infrastructure and Equipment 12.3.1 Blade Server 12.3.2 Storage

357 358 360 360 360 361

11.4

12.3



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12.3.3 Network Equipment 12.3.4 Consolidation 12.3.5 Virtualization 12.3.6 Software Facility Infrastructure 12.4.1 Electrical Infrastructure 12.4.2 HVAC Infrastructure DG and CHP for Data Centres Organizing for Energy Efficiency Further Readings

361 362 362 363 363 363 365 368 369 370

13

Reactive Power Compensation Zbigniew Hanzelka, Waldemar Szpyra, Andrei Cziker and Krzysztof Piatek

371

13.1

Reactive Power Compensation in an Electric Utility Network 13.1.1 Economic Efficiency of Reactive Power Compensation Reactive Power Compensation in an Industrial Network 13.2.1 Linear Loads 13.2.2 Group Compensation 13.2.3 Nonlinear Loads Var Compensation 13.3.1 A Synchronous Condenser 13.3.2 Capacitor Banks 13.3.3 Power Electronic Compensators/Stabilizers References Further Readings

373 377 380 381 383 387 391 391 392 393 398 398

12.4

12.5 12.6

13.2

13.3

Index

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List of Contributors Angelo Baggini Industrial Engineering Department University of Bergamo Via Marconi 5 24044 Dalmine BG, Italy Joan Bergas-Jané Centre d’Innovació Tecnològica en Convertidors Estàtics i Accionaments (CITCEA) Universitat Politècnica de Catalunya (UPC) Escuela Técnica Superior de Ingenier´ıa Industrial de Barcelona Av. Diagonal, 647. Planta 2 08028 Barcelona, Spain Franco Bua ECD Engineering Consulting and Design Vai Maffi 21 27100 Pavia, Italy Mircea Chindris Electrical Power Systems Dept. Technical University of Cluj-Napoca 15, C.Daicoviciu st. 400020 Cluj-Napoca, Romania Andrei Czicker Electrical Power Systems Dept. Technical University of Cluj-Napoca 15, C.Daicoviciu st. 400020 Cluj-Napoca, Romania Wim Deprez Dept. Electrical Engineering ESAT

K.U. Leuven, Research group ELECTA Kasteelpark Arenberg 10 3001 Heverlee, Belgium Stefan Fassbinder Berantung elektrotechnische Anwendungen Deutsches Kupferinstitut Am Bonneshof 5 D-40474 Dusseldorf, Germany Zbigniew Hanzelka University of Science and Technology – AGH 30-059 Cracow, Al. Mickiewicza 30 Poland Joris Lemmens Dept. Electrical Engineering ESAT K.U. Leuven, Research group ELECTA Kasteelpark Arenberg 10 3001 Heverlee, Belgium Annalisa Marra ECD Engineering Consulting and Design Vai Maffi 21 27100 Pavia, Italy Daniel Montesinos-Miracle Centre d’Innovació Tecnològica en Convertidors Estàtics i Accionaments (CITCEA) Universitat Politècnica de Catalunya (UPC) Escuela Técnica Superior de Ingenier´ıa Industrial de Barcelona

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Av. Diagonal, 647. Planta 2 08028 Barcelona, Spain Paola Pezzini Centre d’Innovació Tecnològica en Convertidors Estàtics i Accionaments (CITCEA) Universitat Politècnica de Catalunya (UPC) Escuela Técnica Superior de Ingenier´ıa Industrial de Barcelona Av. Diagonal, 647. Planta 2 08028 Barcelona, Spain Krzysztof Piatek University of Science and Technology – AGH 30-059 Cracow, Al. Mickiewicza 30, Poland Edris Pouresmaeil Centre d’Innovació Tecnològica en Convertidors Estàtics i Accionaments (CITCEA) Universitat Politècnica de Catalunya (UPC) Escuela Técnica Superior de Ingenier´ıa Industrial de Barcelona Av. Diagonal, 647. Planta 2 08028 Barcelona, Spain Jaume Salom Institut de Recerca en Energia de Catalunya (IREC) Jardins de les Dones de Negre 1, 2a pl. 08930 Sant Adrià de Besòs, Spain Antoni Sudrià-Andreu Centre d’Innovació Tecnològica en Convertidors Estàtics i Accionaments (CITCEA) Universitat Politècnica de Catalunya (UPC) Escuela Técnica Superior de Ingenier´ıa Industrial de Barcelona Av. Diagonal, 647. Planta 2 08028 Barcelona, Spain

List of Contributors

Andreas Sumper Centre d’Innovació Tecnològica en Convertidors Estàtics i Accionaments (CITCEA) Universitat Politècnica de Catalunya (UPC) Escola Universitària d’Enginyeria Tècnica Industrial de Barcelona Carrer Comte d’Urgell, 187 - 08036 Barcelona, Spain and Institut de Recerca en Energia de Catalunya (IREC) Jardins de les Dones de Negre 1, 2a pl. 08930 Sant Adrià de Besòs, Spain Waldemar Szpyra University of Science and Technology – AGH 30-059 Cracow, Al. Mickiewicza 30, Poland Roman Targosz Polish Copper Promotional Centre Plac Jana Pawla II 1-2 50-136 Wrocalw, Poland Roberto Villafáfila-Robles Centre d’Innovació Tecnològica en Convertidors Estàtics i Accionaments (CITCEA) Universitat Politècnica de Catalunya (UPC) Escola Universitària d’Enginyeria Tècnica Industrial de Barcelona Carrer Comte d’Urgell, 187 - 08036 Barcelona, Spain Irena Wasiak Politechnika Łódzka Wydział Elektrotechniki, Elektroniki, Automatyki i Informatyki Instytut Elektroenergetyki ul. Stefanowskiego 18/22 90-924 Łód´z, Poland

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Preface Energy efficiency technologies are common technologies from different engineering fields used to reduce the energy required to provide products and services. As electricity is the most flexible energy form known to humans and one of the most important energy forms used in industry and commercial applications, a specific focus on electrical energy efficiency is required. So, electrical energy efficiency is a set of engineering technologies that are dedicated to increasing the electrical energy efficiency of applications. These engineering technologies are very widespread and can vary from power quality engineering to the thermal engineering of electrical applications, including economic aspects. Together with electrical safety, in the coming years electrical energy efficiency should become one of the mandatory design criteria in every process, installation or building. The difficulty of electrical energy efficiency engineering is to obtain a holistic view of an application; in most cases a specific knowledge of the technology is needed, but a deep understanding of the industrial process and the problem to be solved is necessary in order to achieve the overall efficiency goal. Often, optimal solutions for partial problems provide a moderate contribution to the overall energy efficiency of the process. Engineers should have multidisciplinary knowledge, for instance knowledge about electrical applications, power quality, control techniques and heat transfer. Also, an important aspect to consider is the ability to analyse the industrial process and to determine what efficiency actions need to be taken. The increase in electrical energy efficiency is closely related to the evaluation of the efficiency measures to be taken, mainly by investment analysis. Efficient solutions often need higher investments and these usually need management approval. The manager also has to understand how energy efficient solutions can improve the process efficiency and therefore a higher productivity can be achieved. In 2000 a group of academics and industrialists launched a life-long learning programme co-funded by the European Commission dedicated to Power Quality problems called Leonardo Power Quality Initiative (LPQI). This project created a network of experts in energy that created several follow-on projects such as LPQIves and Leonardo Energy. Most of the information on these programmes is available at the Leonardo Energy webpage (http://www.leonardoenergy.org). Inspired by this project, part of this working group contributed to the Handbook of Power Quality, edited by Angelo Baggini in 2008. In one of the project meetings in Brussels in 2008 the idea of a comprehensive book on electrical energy efficiency was born and the content of the book was worked out during the following years.

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Preface

The novel approach in this book is to give the reader a straightforward introduction to the technologies and their applications used to increase electrical energy efficiency. The reader will find efficiency aspects emphasized in this comprehensive book and an expert view given on the most important industrial and commercial fields of electrical engineering. Each chapter covers a different technology in order to achieve an efficiency goal in a wide range of application fields. Before you begin to study this book, we would like to mention the important contributions of all the authors of the chapters from all around the world. Without their expert views, this work would not be possible. We hope that you find this book interesting reading. Andreas Sumper, Barcelona, Spain Angelo Baggini, Pavia, Italy

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Foreword There are no doubts that energy security and climate change are two of the most frequent topics discussed by policy makers. The oil price is now at around US$100 per barrel and, because of the increasing demand and the continuing depletion of the reserves, this price level will stay or may even increase. The human impact on climate change is not disputed anymore in the scientific community, as well as the worrying news that the irreversible impact has already started and only a drastic change in the level of CO2 emissions will mitigate the large and very costly impact on the society. Energy efficiency and energy conservation are gaining importance as key components in many national and international strategies to mitigate the impact of climate change, to improve security of energy supply and increase competitiveness, to preserve natural resources (energy, material and water, amongst others) and also to reduce other energy-related environmental pollution. However, investment in energy efficiency technologies from R&D to implementation, in buildings, equipment and industrial systems, is still far too less than the economics and the energy and climate change situation would suggest. Energy efficiency policies, programmes and support schemes are still very much needed to overcome market, institutional, financial and legal barriers, and to create a favourable market for energy efficiency investments at the level that a rational economic behaviour would justify. In particular, support schemes for energy efficient technologies are very much debated as many consider that the future energy cost savings should be enough to motivate end users. The other major issue is the awareness that what matters in climate change is to reduce the absolute energy demand if we want to mitigate the inevitable full climate change impact. Reduction in energy demand can be achieved by improving the energy efficiency of the service provided (technological aspect) and/or by realising energy savings without necessarily making technological improvements (behavioural aspect, for instance less overheating or overcooling, less driving). Energy efficiency is an important component to achieve energy savings, as it allows having the same services (e.g. lighting, cooling, heating) with less use of energy. However, improved energy efficiency – i.e. replacing a technology with a more energy efficient one – does not per se assure energy savings, and there are numerous examples where as a result of introducing a more efficient technology the actual consumption indeed increases, because of the rebound effect or because of installing larger and more numerous appliances and equipment (larger volume of appliances, more frequent usage). There is an increased interest in energy efficiency and energy savings amongst policy makers, economists and academics (from the technology, economy, policy and human behaviour side). There is the need to further explore energy efficiency technologies (such as control systems,

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Foreword

solid state lighting, variable speed drives and vacuum insulation) and gather new evidence on policies and socio-economic issues related to energy use, consumption and behaviour. At the same time, with increased policy activities in the energy efficiency and energy saving field, there is a new need to evaluate the past and present policies in different countries, to show the clear contribution of energy efficiency to energy security and climate change mitigation. Paolo Bertoldi European Commission Joint Research Centre Ispra Italy

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1 Overview of Standardization of Energy Efficiency Franco Bua and Angelo Baggini

Since the oil shocks of the 1970s, many countries worldwide have promoted energy efficiency improvements across all sectors of their economies. As a result of these policies and structural changes in their economies, these countries have been able to decouple primary energy use from economic growth. The rate of decline in energy intensity has not remained constant over time; in most countries the rate of decline tended to be higher from 1970 to 19901 . The International Energy Agency (IEA) reports that the oil price shocks of the 1970s and the resulting energy policies have apparently been more effective in controlling the growth in energy demand and CO2 emissions than the energy efficiency and climate policies implemented in the 1990s2 . However, since the early 2000s, the rate of improvement in energy intensity has tended to increase, possibly in association with the increase in energy prices and greater attention to climate change issues. It goes without saying that, these days, improving energy efficiency has become a priority in the political agenda of all countries, being key to addressing energy security and both environmental and economic challenges. In order to support governments with their implementation of energy efficiency, many organizations have worked out a broad range of recommendations and proposed actions for

1 IEA 2 IEA

(2007), Energy Use in the New Millennium – Trends in IEA countries, OECD/IEA, Paris. (2007), Energy Use in the New Millennium – Trends in IEA countries, OECD/IEA, Paris.

Electrical Energy Efficiency: Technologies and Applications, First Edition. Andreas Sumper and Angelo Baggini. © 2012 John Wiley & Sons, Ltd. Published 2012 by John Wiley & Sons, Ltd.

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Electrical Energy Efficiency

well identified priority areas3 . Each country would select the policies that best suit its efficiency commitment as well as its unique economic, social and political situation. A classification of these policy options and measures4 is given by the World Energy Council5 as follows:

r Institutions and programmes ◦ Institutions: agencies (national, regional and local), Ministry department ◦ National programmes of energy efficiency with quantitative targets and laws r Regulatory measures ◦ Minimum efficiency standards and labels for electrical appliances (e.g. refrigerators, washing machines, AC, lamps, water heaters, motors), cars and buildings (new and existing) ◦ Other regulations for designated consumers: mandatory energy managers, mandatory energy consumption reporting, mandatory energy saving and mandatory maintenance ◦ Obligation of energy savings for energy companies at consumers’ premises r Financial and fiscal measures ◦ Subsidies for audits by sector (industry, commercial, public, households, low income households transport) ◦ Subsidies or soft loans (i.e. loans with subsidised interest rates) for energy efficiency investment and equipment by sector r Fiscal measures ◦ Tax credit ◦ Accelerate depreciation ◦ Tax reduction for efficiency investment, by type of tax (import, VAT, purchase, annual car registration) and by type of equipment (appliances, cars, lamps) r Cross-cutting measures ◦ Innovative communication tools ◦ Voluntary agreements. Exercises have been carried out extensively to measure how effective these energy efficiency policies are. As an example, IEA reviews the state of the art of the energy efficiency policies, highlighting strengths and areas for improvement (Table 1.1 and Table 1.2). Despite having a huge potential, energy efficiency policies8 are difficult to implement. Why? Energy efficiency faces pervasive barriers, including lack of access to capital for energy efficiency investments, insufficient information, and externality costs that are not reflected in energy prices. Moreover political commitment to maximizing the implementation of energy efficiency policies may also have been challenged by the current economic crisis. Energy 3 For example IEA recommended the adoption of a set of specific energy efficiency policy measures to the last four G8 summits; for further information on the full set of recommendations, refer to http://www.iea.org/ textbase/papers/2008/cd_energy_efficiency_policy/index_EnergyEfficiencyPolicy_2008.pdf 4 A comprehensive database of energy efficiency policies and measures is provided by IEA (http//www.iea .org/textbase/pm/index_effi.asp) 5 WEC, Energy Efficiency: A Recipe for Success, 2010, p. 40. 6 IEA, Implementing Energy Efficiency Policies, 2009, p. 23. 7 IEA, Implementing Energy Efficiency Policies, 2009, p. 33. 8 It is worth mentioning that there is literature on most common criticisms of energy efficiency policies and programmes. These critics argue that energy efficiency policies and programmes are unwarranted or are a failure. IEA promoted the publication of a paper that compiles, categorises, and then evaluates those criticisms of energy efficiency policies (see 7).



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Overview of Standardization of Energy Efficiency

3

Table 1.1 Summary of strengths and innovations in IEA member countries’ energy efficiency policies in the building, industrial and transport sectors6 Buildings

r Full implementation of building certification in several EU countries r Policies promoting passive energy houses r Energy efficiency requirements in building codes

Industry

r High coverage of industry energy statistics in all countries r Policies for promoting energy management r Ad hoc policies for SMEs r Policies for cogeneration, energy efficient electric motors

Transport

r Policies aimed at rolling resistance of tyres r Fuel efficiency standards for light and heavy duty vehicles (JP only) r Eco drive policies r Scrappage schemes encouraging purchase of more efficient and less polluting new vehicles

Table 1.2 Summary of challenges and areas for improvement in IEA member countries’ energy efficiency policies in the building, industrial and transport sectors7 Buildings

Industry Transport

r Establish stronger energy efficiency requirements for buildings r Strengthen support for Passive Houses and zero-energy buildings r Increase promotion of energy efficiency windows and glazing r Establish measures to optimize energy efficiency in motor driven systems r Set up policies and measures to assist SMEs r Ensure the implementation fuel efficiency standards of planned policies r Create fuel efficiency standards for heavy duty vehicles

efficiency programmes must compete for funding with other priorities such as employment, health and social security.

1.1 Standardization As stated above, energy efficiency faces barriers to success. Examples of such barriers include: the lack of awareness of the savings potential, inadequate performance efficiency information and metrics, the tendency to focus on the performance of individual components rather than the energy yield or consumption of complete systems, split incentives and the tendency to focus on lowest initial cost rather than life cycle cost. Standards can help in overcoming some of these barriers. Standards, for instance, can provide common measurement and test methods to assess the use of energy and the reductions attained through new technologies and processes, as well as providing a means of codifying best practices and management processes for efficient energy use and conservation. Furthermore, standards can provide design checklists and guides that can be applied to both the design of new systems and the retrofit of existing systems; they can provide standard



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calculation methods so that sound comparisons of alternatives can be made in specific situations and they can help with the adaptation of infrastructure to integrate new technologies and aid interoperability. An overview of the current standardization activities on energy efficiency is given in the following sections.9

1.1.1

ISO

The work of the ISO (International Organization for Standardization) on energy efficiency began in June 2007 when the ISO Council Task Force on Energy Efficiency and Renewable Energy Sources identified five areas of high priority that were deemed to have the highest potential to contribute substantially to energy savings and greenhouse gas emission reductions, namely:

r Calculation methods r Energy management standards r Biofuels r Retrofitting and refurbishing r Buildings. In line with the Council’s request10 , the Technical Management Board (TMB) established a Strategic Advisory Group (SAG) on Energy efficiency and renewable energy sources11 for an initial period of 2 years (until February 2010). SAG E was asked to provide advice and guidance to TMB on priority standards and actions, including involving stakeholders’ collaboration with other international organizations and co-ordination between ISO and TCs, etc. The goal was to speed up the process of devising a standardization programme in this field that will serve public policy objectives and market needs. SAG-E produced an extensive report, providing 66 recommendations, which were endorsed by the TMB. SAG-E activity has been extended for another 3 years.

1.1.1.1

ISO 50001

In February 2008, the ISO Technical Management Board approved the establishment of a new project committee, ISO/PC 242, Energy management12 , building on practices and existing national or regional standards. ISO 50001 will establish an international framework for industrial and commercial facilities, or entire companies, to manage all aspects of energy, including procurement and use. After four committee meetings, spanning a period of two years, the document was published in June 2011 and was adopted by CEN and CENELEC as ISO EN 50001 in October 2011. The 9 This overview took into account standardization, directly concentrating on energy efficiency from a system approach point of view. 10 Resolution 28/2007. 11 ISO Technical Management Board Resolutions 22/2008. 12 ISO Technical Management Board Resolutions 15/2008.



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standard is intended to provide organizations and companies with a recognized framework for integrating energy efficiency into their management practices. ISO 50001 will provide organizations and companies with technical and management strategies to increase energy efficiency, reduce costs, and improve environmental performance.

1.1.1.2

ISO/IEC JPC 2

In 2009, ISO and the International Electrotechnical Commission (IEC) created the joint project committee ISO/IEC JPC 2, Energy efficiency and renewable energy sources – Common terminology, whose primary objective is to develop a standard that will identify cross-cutting concepts with terms and definitions associated with energy efficiency and renewable energy sources, while taking into account terminology that has already been elaborated in sectorspecific ISO and IEC technical committees. Three working groups (WG) were established at the first meeting of ISO/IEC JPC in January 2010:

r WG 1, Energy efficiency : Concepts and diagrams, coordinated by ANSI (USA) r WG 2, Inputs from existing reference documents, coordinated by SIS/SEK (Sweden) r WG 3, Renewable energy sources – Terms and definitions, coordinated by AFNOR (France). The Committee Draft (CD) step was launched in October 2011.

1.1.2

IEC

IEC’s vision on Energy efficiency is outlined in its White Paper, ‘Coping with the Energy Challenge’13 . Developed by the IEC Market Strategy Board (MSB), this document maps out global energy needs and potential solutions over the next 30 years and the IEC’s role in meeting the challenges. IEC thinks that a system approach that takes into account all aspects of generating, transporting and consuming energy must be considered to cope with the energy efficiency challenges and that measurement procedures and methods of evaluating energy efficiency must be specified in order to assess potential improvements properly and to optimize technological issues (Best Available Technology, BAT).

1.1.2.1

SG1 ‘Energy Efficiency and Renewable Resources’

In 2007 IEC began to establish subsidiary bodies to advise its Management Board on strategic issues that would determine future technical work. Among these was the SG1, which was established on the specific topic of energy efficiency.

13 http://www.iec.ch/smartenergy/



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SG 1 was established at the beginning of 2007 and was tasked to:

r analyse the status quo in the field of energy efficiency and renewable resources (existing IEC standards, on-going projects)

r identify gaps and opportunities for new work in IEC’s field of competence r set objectives for electrical energy efficiency in products and systems r formulate recommendations for further actions. Since then experts from other groups inside the IEC and other organizations such as IEA, CIE, etc. have met to present their activities and achievements in the areas of energy efficiency and renewable resources and to provide their input to the discussions. The main outcomes of SG1’s work are 34 recommendations that were sent to SMB and TC members for comments.

1.1.2.2

SG3 ‘Smart Grid’

In this context it is worth mentioning another Study Group (SG) that is linked to energy efficiency: SG3 ‘Smart Grid’. SG3, set up in 2008, provides advice on fast-moving ideas and technologies that are likely to form the basis for new International Standards or IEC Technical Committees in the area of Smart Grid technologies. SG3 has developed the framework and provides strategic guidance to all Technical Committees involved in Smart Grid work and has developed the Smart Grid Roadmap14 , which covers standards for interoperability, transmission, distribution, metering, connecting consumers and cyber security.

1.1.2.3

SG4 ‘LVDC Distribution Systems up to 1500 V DC’

SG 4 was set up in 2009 with the objective of having a global systematic approach and to align and coordinate activities in many areas where LVDC is used, such as green data centres, commercial buildings, electricity storage for all mobile products (with batteries), EVs, etc, including all mobile products with batteries, lighting, multimedia, ICT, etc. with electronic supply units. SG4 is another example of an area of activity that is not directly dedicated to energy efficiency but whose role could be strategic in harvesting energy efficiency potential.

1.1.3

CEN and CENELEC

CEN and CENELEC were the most proactive standardization organizations as they started in 2002, to analyse the challenges of standardization in the field of energy efficiency and to elaborate general strategy. Another interesting and valuable aspect is that CEN and CENELEC decided to start this activity jointly, thus implementing de facto an integrated system approach that is of utmost importance. 14 http://www.iec.ch/smartgrid/downloads/sg3_roadmap.pdf



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Table 1.3 CEN–CENELEC Joint Working Groups active in the field of Energy Management and Energy Efficiency standardization Technical body JWG1 ‘Energy Audits’ JWG2 ‘Guarantees of origin and energy certificates’ JWG3 ‘Energy Management and related services – General requirements and qualification procedures’

JWG4 ‘Energy efficiency and saving calculation’

Scope of work Standardization on guarantees of origin for trading and/or disclosure/labelling of electricity and CHP and on energy certificates To elaborate EN standards in the energy management and related services field: r Energy Management Systems: definition and requirements r Energy Service Companies (ESCO): definition, requirements and qualification procedures r Energy Managers and Experts: roles, professional requirements and qualification Procedures Standards for common methods of calculation of energy consumption, energy efficiencies and energy savings and for a common measurement and verification of protocol and methodology for energy use indicators

The CEN/CENELEC BT JWG ‘Energy management’ was set up at the beginning of 2002 to initiate a European collective view of the general strategy for improvement of energy efficiency standardization and to set an agreement between all CEN/CENELEC members on the objectives to be achieved. The working group acted as an advisory group to CEN and CENELEC BTs on all political and strategic matters relating to standardization in the field of energy efficiency from 2002 to 2005. The main results of the work are synthesized in a report15 that gives an overview of proposals in standardization in the field of energy management, classified into three level of priorities16 . This document is still the basis for CEN and CENELEC standardization activity in the field of energy efficiency. The key technical bodies involved in energy efficiency standardization are summarised in Table 1.3 together with the most important standardisation activities (Table 1.4).

1.1.3.1

SFEM

In response to the CEN/CENELEC BT JWG ‘Energy management’ recommendation, CEN and CENELEC have created a horizontal structure, a Sector Forum Energy Management (SFEM), dedicated to the definition of a common strategy for standardization in the field of energy management and energy efficiency. SFEM is a platform for stakeholders to share information and experiences, and to identify priorities regarding standardization in the energy sector. 15 http://www.cen.eu/cen/Sectors/Sectors/UtilitiesAndEnergy/Forum/Documents/BTN7359FinalReportJWG.pdf 16 Level A – for immediate action; Level B – that need further investigation or research before standardisation could be done; Level C – that need to be discussed in the context of a strategic and holistic view, i.e. policy questions.



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Table 1.4 CEN–CENELEC standards and projects in the field of Energy Management and Energy Efficiency Publication/Project

Title

EN 16001:2009 (pr=22320)

Energy management systems – Requirements with guidance for use Energy efficiency services – Definitions and requirements Energy audits – Part 1: General requirements Guarantees of origin related to energy – Guarantees of origin for electricity Energy efficiency benchmarking methodology Energy management systems – Requirements with guidance for use Standard on top down and bottom up methods of calculation of energy consumption, energy efficiencies and energy savings

EN 15900:2010 (pr=22416) prEN 16247-1:2011 (pr=23294) prEN 50XXX (pr=23227) prEN PT EEB Doc:2010 (pr=23079) EN ISO 50001:2011 (pr=23639) prEN 16212:2010 (pr=23138)

SFEM is designed:

r to maintain and enlarge the network of partners created during the lifetime of the CEN/ CENELEC BT JWG “Energy Management”, especially with regards to new members;

r to initiate further investigation and to evaluate in which field or for which subject, further standardization work is needed and including subjects identified as Priority B or C by the former CEN/CENELEC BT JWG “Energy Management”; r to coordinate on-going European Standardization activities concerning Energy Management; r to organize the CEN and CENELEC response to European legislation and Europe general strategy in the Energy Management sector; r to maintain the exchange of information, experience and prospecting especially on the initiatives in course in the different countries or at European level. SFEM meets twice a year, does not carry out any standardization activity and formulates recommendations to CEN and CENELEC for further actions. CEN and CENELEC usually react by setting up dedicated technical bodies (usually joint working groups) with specific scopes of work.

Further Readings H. Geller and S. Attali, The experience with energy efficiency policies and programmes in IEA countries. Learning from the Critics, IEA Information Paper, 2005. IEA, Implementing Energy Efficiency Policies, 2009, OECD/IEA, Paris. WEC, WEC: Energy Efficiency: A Recipe for Success, 2010.



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2 Cables and Lines Paola Pezzini and Andreas Sumper

In distribution systems the power transmission capacity is directly given by the product of the operating voltage and the maximum current that can be transmitted. The operating voltage being a fixed value, the delivery capability of the system at a given voltage depends on the conductor’s capacity if carrying current. The delivery capacity is called the ampacity of the cable system [1] and its calculation is carried out taking into consideration both steady state and transient calculations [2]. The calculations for cables in air and for buried cables are slightly different, due to the surrounding medium with which the cable has to interact. The ampacity calculations for air cables should take into account solar radiation and the amount of wind in the area in which the cable system is installed. Ampacity calculations for buried cables should consider the soil in which the cable system is installed. Ampacity calculations require the solution of the heat transfer equations because insulation and cable size are independent parameters, inter-related by thermal considerations. Cable ampacity calculations require the determination of the temperature of the conductor for a given current loading. The ampacity rating is directly proportional to the conductor size: the larger the conductor size (lower Joule losses) the higher the ampacity. On the other hand, the insulation requirements are determined by the operating voltage and they also directly influence the ampacity value: high insulation requirements (lower heat dissipation) mean a lower ampacity. The parameters that influence the value of the ampacity are the number and types of cable, the thermal resistance of the medium surrounding the cable (soil or air), the depth of burial in the case of buried cables and the horizontal spacing between the cables of the system. The clear relationship between the conductor current and the temperature leads to a study of how the heat generated while a current is transmitted is dissipated. The resolution of the basic heat transfer equations is the first step to achieving the cable rating calculations and cable ampacity; they depend mainly on the efficiency of the dissipation process, along with the limits imposed on the insulation temperature.

Electrical Energy Efficiency: Technologies and Applications, First Edition. Andreas Sumper and Angelo Baggini. © 2012 John Wiley & Sons, Ltd. Published 2012 by John Wiley & Sons, Ltd.

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Technical criteria alone are nowadays not enough to obtain the best sizing for a cable. In fact, the minimum admissible section obtained from the solution of the heat transfer equations does not take into account the cost of the losses that will be present during the cable’s lifetime. The selection of the cable size should therefore take into consideration the sum of the initial cost and the cost of the losses: the cost of energy losses can be calculated by estimating load growth and the cost of energy. If the sum of the future costs of energy losses and the initial cost of purchase and installation are minimized, then the most economical size of conductor has been achieved. Using this minimization, the saving in overall cost is due to the reduction in the cost of the Joule losses compared with the increase in the cost of purchase.

2.1

Theory of Heat Transfer

An overview of the heat transfer theory is presented here because load current and conductor temperature are strictly related. The heat generated in the cable system and the rate of its dissipation must be calculated, for a given conductor material and for a given load, in order to determine the conductor temperature for a given current loading or to determine the tolerable load current for a given conductor temperature [2]. There are different mechanisms that explain how heat is transferred in different media: these three mechanisms are conduction, convection and radiation.

2.1.1

Conduction

For heat conduction, the rate equation used to express the transfer of heat between two media in contact is the equation known as Fourier’s law, as in: Q=−

1 dθ A . ρ dx

(2.1)

The thermal power in the x direction is represented by Q [W] and it is directly proportional to K the temperature gradient ddθx m . This gradient represents, for a given temperature distribution, 2 θ (x) [K], the direction and the rate at which temperature changes. A [m ] is the area in K mthe which the thermal exchange occurs and ρ W is the thermal resistivity, a transport quality characteristic of the material. The minus in the equation represents the fact that heat is transferred in the direction of the decreasing temperature. Conduction is the mechanism that acquires more importance when considering buried cables, where the conductor is in contact with other metallic parts and insulation.

2.1.2

Convection

Convection is the result of two mechanisms that work simultaneously: heat transfer conduction due to the presence of molecular motion and heat transfer due to fluid motion. The equation employed to describe convection is Newton’s law: Q = hA (θs − θamb ) .

(2.2)



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Cables and Lines

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Table 2.1 Range of values for the heat convection coefficient, h Mechanism Heat coefficient, h W/K m2 Natural convection Forced convection Gas Fluids Boiling and condensation

5–25 25–250 50–20000 2500–100 000

The convection thermal power Q [W] is proportional to the temperature difference between the temperature, θ amb A [m2 ] is again the area of the thermal exchange surface θ s andthe ambient W surface and h K m2 is the convection heat transfer coefficient. Convection can be classified according to the fluid motion: forced convection and free convection. The first occurs when the flow is caused by external means: wind, pumps or fans. The second arises from density differences caused by temperature variations. Convection must be strongly taken into account for cables installed in air and the heat convection coefficient, h is the most important parameter to be calculated. Table 2.1 shows the typical range of values for the h coefficient.

2.1.3

Radiation

Energy transmission by radiation is a characteristic of all matter; it does not need a medium: radiation travels by means of electromagnetic waves, which can transmit energy in a vacuum. The thermal power emitted follows Stefan–Boltzmann’s law: Q = εAσB θs∗4

(2.3)

∗ The thermal power Q is directly proportional θS [K] of the surface, to the absolute temperature

A [m2 ], σB is Stefan–Boltzmann’s constant σB = 5.67 · 10−8 K4Wm2 and ε is the emissivity, a radiative property of the surface. Emissivity is the efficiency of a surface to emit, compared with an ideal radiator and its range of values is 0 ≤ ε ≤ 1. If radiation is incident on a surface, a portion will be absorbed according to the surface radiative property known as absorptivity, α [W/K4 m2 ], as presented in the following equation: Qabs = αQinc ,

(2.4)

where 0 ≤ α ≤ 1. Cables both emit and absorb radiation. Therefore to determine the net rate the following equation is employed: ∗4 Q = εAr σB θS∗4 − θamb . (2.5) In cable systems installed in air, convection must also be taken into account, so finally the equation that should be applied is: ∗4 Q = hAc (θs − θamb ) + εAr σB θs∗4 − θamb , (2.6) where Ac [m] is the convection surface and Ar [m] is the radiation surface.



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2.2


Current Rating of Cables Installed in Free Air

The permissible current rating of cables is calculated basically using four main values: permissible temperature rise, conductor resistance, losses and thermal resistivity. However, some quantities vary with cable design and material, so one needs to rely on an international standard. Moreover, as will be explained later, the quantities relating to the operating conditions may vary from one country to another. Considering AC cables in air, the permissible current rating is [3]: 0.5

θ − Wd [0.5 T1 + n (T2 + T3 + T4 )] , (2.7) I= RT1 + nR (1 + λ1 ) T2 + nR (1 + λ1 + λ2 ) (T3 + T4 ) where θ [K] is the permissible temperature rise of a conductor above ambient temperature, W d [W/m] represents the dielectric losses per unit length per phase, n is the number of conductors in the cable, R [Ω/m] is the alternating current resistance of the conductor at its maximum operating temperature and Ti [K m/W] represents the thermal resistance, more specifically: T 1 is the thermal resistance per core between conductor and sheath, T 2 is the thermal resistance between sheath and armour, T 3 is the thermal resistance of the external serving and T 4 is the thermal resistance of the surrounding medium. To evaluate the losses, several quantities are considered: AC resistance, dielectric losses, sheath and screen losses, armour, reinforcement and steel pipes losses. Here only AC resistance and dielectric losses are discussed, a further discussion on sheath and screen losses, armour, reinforcement and steel pipes losses can be found in the IEC 60287-1-1 [3]. Considering its maximum operating temperature, the AC resistance per unit length of the conductor is given by: (2.8) R = R 1 + ys + yp , where R [Ω/m] is the AC current resistance of conductor at maximum operating temperature, R is the DC resistance of conductor at maximum operating temperature, ys is the skin effect factor and yp the proximity effect factor. The evaluation of these quantities can be done by IEC 60287-1-1 [3]. When a cable carries alternating current, the resistance is higher than when it carries direct current, mainly because of the skin effect, proximity effect, hysteresis and eddy current losses in ferromagnetic materials and the induced losses in short-circuited non-ferromagnetic materials [2]. Usually, only the skin and proximity effects are considered, except in very high voltage cables. The dielectric losses per unit length in each phase are given by: Wd = ω CU02 tan δ,

(2.9)

where ω = 2π f , C [F/m] is the capacitance per unit length and U 0 [V] is the voltage to earth. Applying alternating voltage to paper and solid insulation causes charging currents to flow because the insulation acts as a large capacitor. Each time the voltage direction changes, the electrons must be realigned, expending a certain amount of work, which will produce heat and therefore a loss in real power, the dielectric loss [2]. As can be seen by its equation, the dielectric loss is voltage dependent and Table 3 of the IEC 60287-1-1 [3] gives, for the common used insulation materials, the value of U 0 . The rest of the quantities in the equation for the dielectric losses can be also be found in the same table.