This work is focused on the locating of faults of the cables laid in the ground. Firstly it describes particular types of cables and their basic physical characteristics. Following part deals with widely used methods for locating cable faults including their comparison. Than it describes DC measurements which are used to identify the type of fault. In the practical part there is a complete DC measurement on the specific cable and finding out the limits of usefulness regarding to the chosen methods for locating the failures.

abstract: The utilization of power cables is increasing with the development of renewable energy and the maintenance replacement of old overhead power lines. Therefore, effective monitoring and accurate fault location for power cables are very important for the sake of a stable power supply. The recent technologies for power cable diagnosis and temperature monitoring system are described including their intrinsic limitations for cable health assessment. Power cable fault location methods are reviewed with two main categories: off-line and on-line data based methods. As a diagnostic and fault location approach, a new passive methodology is introduced. This methodology is based on analyzing the resonant frequencies of the transfer function between the input and output of the power cable system. The equivalent pi model is applied to the resonant frequency calculation for the selected underground power cable transmission system. The characteristics of the resonant frequencies are studied by analytical derivations and PSCAD simulations. It is found that the variation of load magnitudes and change of positive power factors (i.e., inductive loads) do not affect resonant frequencies significantly, but there is considerable movement of resonant frequencies under change of negative power factors (i.e., capacitive loads). Power cable fault conditions introduce new resonant frequencies in accordance with fault positions. Similar behaviors of the resonant frequencies are shown in a transformer (TR) connected power cable system with frequency shifts caused by the TR impedance. The resonant frequencies can be extracted by frequency analysis of power signals and the inherent noise in these signals plays a key role to measure the resonant frequencies. Window functions provide an effective tool for improving resonant frequency discernment. The frequency analysis is implemented on noise laden PSCAD simulation signals and it reveals identical resonant frequency characteristics with theoretical studies. Finally, the noise levels of real voltage and current signals, which are acquired from an operating power plant, are estimated and the resonant frequencies are extracted by applying window functions, and these results prove that the resonant frequency can be used as an assessment for the internal changes in power cable parameters such as defects and faults. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2015

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22414号 / 工博第4675号 / 新制||工||1729(附属図書館) / 京都大学大学院工学研究科社会基盤工学専攻 / (主査)教授 杉浦 邦征, 教授 河野 広隆, 教授 八木 知己 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

The underground power cable failures introduce challenges to the reliability of underground residential distribution networks. Smart Grid initiatives have interest to improve equipment reliability. Asset management of several utilities are interested towards online cable insulation condition monitoring and health index evaluation. This dissertation demonstrates a new technique for online condition assessment of power cable insulation condition based on capacitor switching transient voltage measurements. While majority of utilities in USA are following corrective maintenance for MV cables, only few utilities have procedures in place for offline preventive maintenance of MV cables. The technique demonstrated in this research will enable all utilities to carry out preventive online monitoring of MV power cables. This dissertation also demonstrates that capacitive test point of cable elbow connector can be used to measure switching transients for power cables in service. This technique can be easily incorporated into existing capacitive test points of cable accessories. This technique has a potential to develop and deploy measurement units for online monitoring of power cables.

京都大学 / 新制・課程博士 / 博士(工学) / 甲第24606号 / 工博第5112号 / 新制||工||1978(附属図書館) / 京都大学大学院工学研究科機械理工学専攻 / (主査)教授 松野 文俊, 教授 松原 厚, 教授 泉井 一浩 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

No description available.

No description available.

The work is based on a problem at the company NKT HV Cables AB, Karlskrona. NKT manufactures high-voltage cables which are pulled through complex cableways. The cables are stiff and difficult to bend, which results in them getting stuck in the cableways. In some parts of the factory, one cable will push another cable. This can also result in the cables getting stuck.During the work, a prototype has been constructed which will prevent the cables from getting stuck in the cableways. This prototype is a bendable ball joint which is attached to the cable end. The ball joint bends the cable end into the tracks, which results in the cable following along. This constructionwas developed through literature studies, concept generation, concept screening, calculations, and testing. FEM calculations were carried out and resulted in the ball joint being able to withstand the forces that occur when pulling forward. This was also verified by a test in an active production line. The result was that the ball joint bent the cable into the cableways and the functionality was confirmed. For optimal function, a rigid connection between the cables is needed in order not to get stuck when the cable pushes the other. The delimitation is important in future development as this problem can persist without a rigid connection. / Arbetet grundas i ett problem på företaget NKT HV Cables AB, Karlskrona. NKT tillverkar högspänningskablar vilka dras genom komplexa kabelbanor. Kablarna är styva och svåra att böja vilket resulterar i att de fastnar i kabelbanorna. I vissa delar av fabriken kommer en kabel putta fram en annan kabel. Även detta kan resultera i att kablarna fastnar i kabelbanorna.Under arbetet har en prototyp konstruerats vilket skall förhindra att kablarna fastnar i kabelbanorna. Denna prototyp består av en böjbar kulled vilket fästs på kabeländen. Kulleden böjer in kabeländen i banorna vilket resulterar i att hela kabeln följer med. Denna konstruktion togs fram genom litteraturstudier, konceptgenerering, konceptsållning, beräkningar och testningar. FEM-beräkningar utfördes och resulterade i att kulleden tål krafterna vilkauppstår vid framdragning. Detta verifierades även genom att testa kulleden i ett framdrag på en aktiv linje i produktionen. Resultatet var att kulleden böjde in kabeln i kabelbanorna och funktionaliteten bekräftades. För optimal funktion krävs en stel koppling mellan kabel och kabel för att inte fastna när en kabel puttar en annan. Avgränsningen är viktig i framtida utveckling då detta problem kan kvarstå utan en stel koppling.

by Leung Chi Wai, Wong Shan Ki. / Thesis (M.B.A.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (leaves 101-104). / Questionnairies also in Chinese. / ABSTRACT / TABLE OF CONTENTS / LIST OF TABLES / LIST OF FIGURES / ACKNOWLEDGMENT / CHAPTER / Chapter 1. --- INTRODUCTION --- p.1 / Chapter 1.1 --- Overview --- p.1 / Chapter 1.1.1 --- Reason for Study --- p.1 / Chapter 1.1.2 --- Approach for Study --- p.2 / Chapter 1.2 --- Market Overview --- p.4 / Chapter 1.2.1 --- Market Definition --- p.4 / Chapter 1.2.2 --- Competitions --- p.5 / Chapter 1.2.3 --- Market Size --- p.7 / Chapter 1.3 --- Company Profile --- p.11 / Chapter 1.3.1 --- Overview --- p.11 / Chapter 1.3.2 --- Product --- p.12 / Chapter 1.3.3 --- Pricing --- p.13 / Chapter 1.3.4 --- Distribution --- p.14 / Chapter 1.3.5 --- Promotion --- p.15 / Chapter 1.3.6 --- Market Share and Penetration --- p.15 / Chapter 1.4 --- Research Objectives --- p.16 / Chapter 2. --- LITERATURE REVIEW --- p.17 / Chapter 2.1 --- Market Segmentation --- p.17 / Chapter 2.1.1 --- Benefits of Market Segmentation --- p.18 / Chapter 2.1.2 --- Characteristics of a Market Segment --- p.19 / Chapter 2.1.3 --- Psychographic Segmentation --- p.20 / Chapter 2.2 --- Cable TV Industry --- p.27 / Chapter 2.2.1 --- Reasons of subscribing Cable TV --- p.27 / Chapter 2.2.2 --- Comparison of Cable subscribers and non-subscribers --- p.29 / Chapter 2.2.3 --- Other related issues --- p.30 / Chapter 3. --- RESEARCH OBJECTIVES --- p.33 / Chapter 3.1 --- Strategic Problems --- p.33 / Chapter 3.2 --- Research Problems --- p.33 / Chapter 4. --- RESEARCH METHODOLOGY --- p.35 / Chapter 4.1 --- Exploratory Study --- p.35 / Chapter 4.2 --- Questionnaire Design --- p.36 / Chapter 4.2.1 --- Basic Construct --- p.36 / Chapter 4.2.2 --- Pilot Survey --- p.36 / Chapter 4.2.3 --- Final Version --- p.37 / Chapter 4.3 --- Sampling --- p.38 / Chapter 4.3.1 --- Survey Subject --- p.38 / Chapter 4.3.2 --- Sampling Size --- p.39 / Chapter 4.3.3 --- Sampling Method --- p.40 / Chapter 4.3.4 --- Representativeness Enhancing Arrangements --- p.40 / Chapter 4.3.5 --- Fieldwork --- p.42 / Chapter 5. --- IDENTIFICATION OF MARKET SEGMENTS --- p.45 / Chapter 5.1 --- Survey Result --- p.45 / Chapter 5.1.1 --- Summary of Data --- p.45 / Chapter 5.1.2 --- Response Rate --- p.47 / Chapter 5.1.3 --- Weighting System --- p.47 / Chapter 5.2 --- Factor Analysis --- p.48 / Chapter 5.2.1 --- Needs of Factor Analysis --- p.48 / Chapter 5.2.2 --- Factors Identification --- p.49 / Chapter 5.2.3 --- Interpretation of Factors --- p.51 / Chapter 5.3 --- Cluster Analysis --- p.53 / Chapter 5.3.1 --- Preliminary Transformation --- p.53 / Chapter 5.3.2 --- Determination of Number of Clusters --- p.55 / Chapter 5.3.3 --- Clusters Identification --- p.58 / Chapter 6. --- INTERPRETATION AND PROFILING OF MARKET SEGMENTS --- p.59 / Chapter 6.1 --- Overall Profile --- p.59 / Chapter 6.1.1 --- Demographic Information --- p.59 / Chapter 6.1.2 --- Media Consumption --- p.60 / Chapter 6.2 --- Segmentation Analysis --- p.61 / Chapter 6.2.1 --- Segment 1 - Conservative TV Dependents --- p.61 / Chapter 6.2.2 --- Segment 2 - Fashion Followers --- p.62 / Chapter 6.2.3 --- Segment 3 - Yuppies --- p.63 / Chapter 6.2.4 --- Segment 4 - Value Minders --- p.64 / Chapter 6.2.5 --- Segment 5 - Conservative TV Satisfiers --- p.65 / Chapter 6.2.6 --- Segment 6 - Community and Family Carers --- p.66 / Chapter 6.3 --- Media Consumption Pattern --- p.70 / Chapter 6.3.1 --- Daily Media Usage & Cable Subscription Patterns --- p.70 / Chapter 6.4 --- Other Findings --- p.75 / Chapter 6.4.1 --- Most Favorite Television Programs --- p.75 / Chapter 6.4.2 --- Reason for Cable subscription --- p.76 / Chapter 6.4.3 --- Reasons of not subscribing Cable --- p.76 / Chapter 7. --- LIMITATION OF THE STUDY --- p.80 / Chapter 8. --- DISCUSSION --- p.82 / Chapter 8.1 --- Current Achievement --- p.82 / Chapter 8.1.1 --- Product Life Cycle --- p.82 / Chapter 8.1.2 --- Image Built --- p.83 / Chapter 8.2 --- "Who Subscribe, who not?" --- p.84 / Chapter 8.3 --- Reasons of Subscribing --- p.86 / Chapter 8.4 --- Reasons of Not Subscribing --- p.87 / Chapter 8.5 --- Marketing Niches --- p.88 / Chapter 9. --- RECOMMENDATION --- p.90 / Chapter 9.1 --- Target Segments --- p.90 / Chapter 9.2 --- Product Strategy --- p.91 / Chapter 9.2.1 --- General Aspects --- p.91 / Chapter 9.2.2 --- Program Mix --- p.91 / Chapter 9.3 --- Promotion Strategy --- p.96 / Chapter 9.3.1 --- Personal Selling --- p.97 / Chapter 9.3.2 --- Advertising --- p.97 / Chapter 9.3.3 --- Free Trial --- p.98 / Chapter 9.4 --- Pricing Strategy --- p.99 / Chapter 9.5 --- Distribution Strategy --- p.99 / Chapter 10. --- CONCLUSION --- p.100 / BIBLIOGRAPHY / APPENDICES / Chapter APPENDIX A --- DESCRIPTION OF CABLE CHANNELS / Chapter APPENDIX B --- SUBSCRIPTION PACKAGES OF CABLE TV / Chapter APPENDIX C --- PILOT QUESTIONNAIRE / Chapter APPENDIX D --- FINAL VERSION QUESTIONNAIRE (ENGLISH) / Chapter APPENDIX E --- FINAL VERSION QUESTIONNAIRE (CANTONESE) / Chapter APPENDIX F --- INTERVIEWER GUIDELINES / Chapter APPENDIX G --- LIST OF AIO STATEMENTS / Chapter APPENDIX H --- CHOICE BROAD / Chapter APPENDIX I --- FACTOR MATRIX / Chapter APPENDIX J --- PSYCHOGRAPHIC PROFILES OF SIX SEGMENTS / Chapter APPENDIX K --- DEMOGRAPHIC PROFILES OF ALL RESPONDENTS / Chapter APPENDIX L --- DEMOGRAPHIC PROFILES OF SIX SEGMENTS / Chapter APPENDIX M --- MOST FAVORITE TELEVISION PROGRAM TYPES / Chapter APPENDIX N --- MOST FAVORITE CABLE TV CHANNELS

Cables are highly nonlinear structural members under transverse loading. This nonlinearity is mainly due to the close relationship between the final geometry under transverse loads and the resulting stresses in its equilibrium state rather than the material properties. In practice, the cables are usually used as isolated single-segment elements fixed at the ends. Various studies and solution procedures suggested by researchers are available in the literature for such isolated cables. However, not much work is available for continuous cables with multiple supports. In this study, a multi-segment continuous cable is defined as a cable fixed at the ends and supported by a number of stationary roller supports in between. Total cable length is assumed constant and the intermediate supports are assumed to be frictionless. Therefore, the critical issue is to find the distribution of the cable length among its segments in the final equilibrium state. Since the solution of single-segment cables is available the additional condition to be satisfied for multi-segment continuous cables with multiple supports is to have stress continuity at intermediate support locations where successive cable segments meet. A predictive/corrective iteration procedure is proposed for this purpose. The solution starts with an initially assumed distribution of total cable length among the segments and each segment is analyzed as an independent isolated single-segment cable. In general, the stress continuity between the cable segments will not be satisfied unless the assumed distribution of cable length is the correct distribution corresponding to final equilibrium state. In the subsequent iterations the segment lengths are readjusted to eliminate the unbalanced tensions at segment junctions. The iterations are continued until the stress continuity is satisfied at all junctions. Two alternative approaches are proposed for the segment length adjustments: Direct stiffness method and tension distribution method. Both techniques have been implemented in a software program for the analysis of multi-segment continuous cables and some sample problems are analyzed for verification. The results are satisfactory and compares well with those obtained by the commercial finite element program ANSYS.