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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
171

Computer tomography dose index for head CT in northern Nigeria

Garba, Idris January 2014 (has links)
Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Diagnostic Radiography, Department of Nursing and Radiography in the Faculty of Health Wellness Sciences at Cape Peninsula University of Technology 2014 / Aim: The aim of this study was to record the values of CTDIw and DLP displayed on the Computed Tomography (CT) scanner monitors of patients undergoing CT examinations of the head as Diagnostic Reference Levels (DRL) for dose optimisation in Northern Nigeria. Background: A brain CT scan is the most common CT examination performed, and this modality is recognized as delivering a high dose. CT, therefore, contributes significantly to the total collective effective dose to the population. Elimination of unnecessary or unproductive radiation exposure is necessary. To achieve this, practitioners must adhere to the principles of the justification of practices, and optimisation of radiation protection. Furthermore, the development of DRLs for the local context is advised. These reference doses are a guide to the expected exposure dose from a procedure and are useful as an investigation tool to identify incidences where patient doses are unusually high. Methodology: The study was conducted in three radiology departments with CT centres in Northern Nigeria. Data was collected, using a purposive sampling technique, from 60 consenting adult participants (weighing 70 ±3 kg) that had brain CT scans on seventh generations 4&16-slice GE and 16-slice Philips CT scanners. Prior to commencement of the study the CT scanners were certified by the medical physicists. For each brain scan, patient information, exposure factors, weighted computed tomography dose index (CTDIw), volume computed tomography dose index (CTDIvol) and dose length product (DLP) values were recorded. The data were analysed using SPSS version (16) statistical software. The mean, standard deviation and third quartile values of the CTDIw and DLP were calculated. An inter-comparison of the measured doses from the three research sites was conducted. A combined dose for the three centres was calculated, and compared with the reported data from the international communities where there are established DRLs. Results: The mean CTDIw and DLP values were: centre A (88 mGy and 713 mGy.cm), centre B (68 mGy and 1098 mGy.cm), and centre C (70 mGy and 59 mGy.cm). Comparison of CTDIw and DLP for the scanners of the same manufacturers showed statistically significant differences (p=0.003) and (p=0.03) respectively. In the case of the scanners of a different model but the same number of slices, the comparison of DLP was statistically significant (p=0.005) while no significant difference was noted in the measured CTDIw. Third quartile values of the cumulative doses of CTDIw and DLP, for Northern Nigeria were determined as 77 mGy and 985 mGy.cm respectively. Conclusion: The study has established Local DRLs (LDRLs) which are significantly higher than most of the reported data in the literature. Also dose variation between centres was noted. Optimization is thus recommended. Keywords: Head Imaging, Radiation Dose, Dose optimization, Computed Tomography, Local Diagnostic Reference Levels, Radiation Protection
172

Ultrasound evaluation of the extracranial cerebrospinal venous system and carotid arteries in patients with multiple sclerosis

Nelson, Merlisa Claudia January 2013 (has links)
Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Radiography in the Faculty of Health and Wellness Sciences at the Cape Peninsula University of Technology Supervisor: Ms. Ferial Isaacs Co-supervisor: Prof. Susan J. Van Rensburg Bellville September 2013 / Multiple Sclerosis (MS) is characterised by demyelination within the central nervous system (CNS), which may result in neurological disabilities over time, causing considerable hardship to patients and their families, in addition to being costly to treat. Recent studies have linked MS to impaired cerebral blood flow, called chronic cerebrospinal venous insufficiency (CCSVI). Anecdotal evidence has suggested that surgical correction thereof results in improvement of symptoms experienced by MS patients. To my knowledge, no information is available in the literature on carotid artery disease in MS. The USA National MS Society has therefore called for more research to be done in this area. This cross-sectional observational sub-study will determine, by ultrasound (B-Mode, Colour and Pulsed-wave Doppler), the prevalence of chronic venous insufficiency (CCSVI) and carotid artery disease in the selected sample of MS patients within the region of the Western Cape, South Africa. Biochemical data; lifestyle factors such as physical activity and smoking; and nutritional status of MS patients were determined from the main study entitled: “The development of a comprehensive gene-based, pathology supported intervention program for improved quality of life in patients diagnosed with multiple sclerosis” (Division of Chemical Pathology, NHLS, Tygerberg Hospital, and University of Stellenbosch). Twenty-nine (29) patients were aged between 28-64years and they suffered from MS for 0.83-27years. A larger proximal and mid cross-sectional diameter (CSD) of the right IJV compared to the left (differences significant, P= 0.026 and P=0.023) was demonstrated. Increased intima media thickness (IMT) was present in 13.33% of the non-smoking MS group and 20% in the smoking MS group. IJV reflux was evident in 13.33% of the MS group. A significant reduction of cross-sectional diameters of the IJV’s was evident in smoking MS patients; suggesting that smoking is not only a risk factor for atherosclerotic disease but could also be related to narrowing of the major neck veins. This study also supports findings of other studies viz that there’s no significant correlation between extracranial venous abnormalities and MS. Early carotid artery disease was noted in smoking and non-smoking MS patients, however the findings were non-significant.
173

The effectiveness of implementing eco initiatives to recycle water and food waste in selected Cape Town hotels

De Lange, Ruan January 2012 (has links)
Thesis submitted in fulfillment of the requirements for the degree Master of Technology: Tourism and Hospitality Management in the Faculty of Business at the Cape Peninsula University of Technology, 2012 / The objective of the research study was to investigate how effective an eco initiative to recycle water and food waste would be when implemented in selected Cape Town hotels. Earthworm farms are able to convert organic food waste into usable compost as an alternative to landfills. Harvesting rainwater as a direct method for the reuse of waste water makes it possible to store captured rainwater for future use. This serves as an alternative source of surface water. The study further investigated whether implementing these initiatives would be successful as a future endeavour. Environmental movements were the instigators of the high demand for recycling initiatives. These movements aimed to address the deteriorating quality of water supplies, as well as growth in landfills. In South Africa, a decrease in the availability and quality of surface water has been coupled with an annual increase of 3.7 % in the demand for water. Landfills furthermore release toxic smoke when burned. Within the Hospitality Industry, travelers are increasingly seeking out environmentally friendly hotels as part of their corporate travel policy. This has occurred as a result of the increased focus on environmental initiatives by the International community. The researcher therefore aimed to provide practical examples of how existing theory regarding these initiatives is applicable to operations within hotels. The research methodology was determined through analysing the research strategy, the design and the research instruments. The research strategy was based on gathering facts relevant to the theory of the study. A descriptive approach was therefore adopted as the “-what-” question that was asked when measuring data to answer the research questions. The research design utilised a multi-strategy approach whereby both quantitative and qualitative data were gathered. This resulted in questionnaires, interviews and case studies forming part of the research instruments. The researcher found it effective to corroborate the findings from both quantitative and qualitative data: that is, the findings from the questionnaires were enhanced by the findings from the interviews. The case studies were conducted to provide a practical context to the theory. Recommendations have been made according to technological and social developments. Ultimately, this study illustrates the success of eco initiatives aimed at recycling water and food waste produced by selected hotels in Cape Town and a reduction in the waste generated by the hotels.
174

Effectiveness of the Eastern Cape provincial department of local government and traditional affairs to monitor and evaluate the performance of municipalities: a case study of Cacadu District Municipality

Gopane, Ogomoditse Mabel January 2012 (has links)
Thesis submitted in fulfilment of the requirements for the degree Master of Technology in Public Management in the Faculty of business at the Cape Peninsula University of Technology, 2012 / South Africa has been experiencing poor service delivery protests. The Eastern Cape in particular, is characterised by rural areas owing to segregation that was created by the past apartheid government. Ineffective operations of municipalities are usually found to be the root cause of ineffective service delivery. However, the Republic of South Africa‟s Constitution,1996 and other forms of legislation provide for monitoring and support of municipalities by national and provincial government, although most monitoring and support responsibilities are borne with the provincial government. Provincial governments provide an oversight role towards municipalities and assist them when they cannot and do not fulfil their obligations. This study focuses on the Eastern Cape with the Cacadu District Municipality as the identified case-study. The district is one of the largest in the Eastern Cape and is marked by high levels of poverty and unemployment. The study investigates the effectiveness of the Eastern Cape Department of Local Government and Traditional Affairs (ECDLGTA) to monitor and evaluate municipalities, with reference to the Cacadu District Municipality. Monitoring and evaluation are effective tools, which are utilised by developed countries to achieve good governance and effective service delivery. South Africa has also followed a culture of M&E and established the Government Wide Monitoring and Evaluation System. It is important that monitoring and evaluation systems are effective. Because with effective systems, government can detect early warning signs of corruption or any other forms of ineffectiveness. The purpose of this research study is to explore current systems that the ECDLGTA has established to monitor municipalities and to assess whether those systems are effective or not. Furthermore, the research intends to explore the reasons for ineffectiveness, as well as the relationship between the municipalities and the provincial government. In order to reach conclusions to these questions, an empirical study was conducted by using qualitative research methodology. Interviews were conducted and are described in chapter five. Chapter Six and Seven present the results that were achieved from the interviews and analysis of those results, whilst Chapter eight presents concluding remarks and recommendations based on the findings.
175

Sustainability of South African FMCG SMME retail businesses in the Cape Peninsula

Bruwer, Juan-Pierre January 2010 (has links)
Dissertation submitted in fulfilment of the requirements for the MTech: Internal Auditing In the Faculty of Business at the CAPE PENINSULA UNIVERSITY OF TECHNOLOGY, 2010 / The concept of Small Medium and Micro Enterprises (SMMEs) was created and implemented by the South African Government in an attempt to improve the economy of South Africa, reducing the unemployment rate and eliminating poverty. As a basic objective, SMMEs strive toward sustainability, however in recent years sustainability is at an all time low as substantial a number of these businesses fail to become viable entities. Popular literature show that Fast Moving Consumer Goods (FMCG) retail SMMEs make ineffective use of their accounting resources, resulting in them making critical business decisions without understanding and interpreting their financial performance or financial positions. These decisions have a ‘toxic’ affect on their business sustainability and as a result, it is perceived that these SMMEs make inefficient use of financial performance measures. The key objective of this research is to establish what financial performance measures sourced from accounting resources are regarded as being critical for the sustainability of FMCG retail SMMEs during the current dispensation of an economic depression in South Africa. To achieve the above dispensation, applied research will be used using ‘action research’ as the primary research paradigm supported by questionnaires for the purpose of data analysis, results of which were analysed using descriptive and inferential statistics. Recommendations culminate from the research to mitigate the research problem.
176

The relationship between organisational commitment and intention to resign in a large employer in the telecommunications industry

Arendolf, Ronwan January 2013 (has links)
Thesis submitted in partial fulfilment of the requirements for the degree Master of Technology: Human Resource Management in the Faculty of Commerce at the Cape Peninsula University of Technology, 2013 / The researcher decided to replicate an existing study by Rahman, Naqvi and Ramay (2008) titled “Measuring Turnover Intention: A Study of IT Professionals in Pakistan”. The study was applied to new situations in order to determine generalisability to different subjects, age groups, races, locations, cultures or any such variables. The replicated study builds on the original study, by making it relevant today and applying it to a large business within the South African Telecommunications industry. Reducing employee turnover is both strategic and very important in ensuring that an organisation remains profitable. Therefore the main objective of this study is to analyse and verify whether job satisfaction, organisational commitment and perceived alternative job opportunities are correlated with turnover intention. Employee turnover has become a serious management problem for the participating company due to the financial and moral impact on its degree of competitiveness and sustainability prospects. Today, organisations are finding it difficult to retain employees. Many skilled professionals are leaving, which results in the loss of knowledge systems and discontinuity for the Telecommunications industry. Thus, employee turnover demands management’s attention to do whatever it can to retain skilled employees. A quantitative research design using a survey was employed in the study. A survey is defined as “a method for gathering information from a sample of individuals” (Scheuren, 2004: 9). A sample was chosen from a population of employees who are working for the participating company, within the Telecommunications industry. The population is N = 401 (unit of analysis), which is the number of people employed at the participating company, where the researcher is currently employed. The General Job Satisfaction Survey (JDS) developed by Hackman and Oldman (Cook & Rice, 2003: 37) was used to measure both JS and PAJO. Hypothesis 1 addressed the relationship between job satisfaction and turnover intention. The Pearson product-moment correlation coefficient (PPMCC) between job satisfaction and turnover intention was r = 0.812 with a p-value = 0.714*, indicating that the correlation is positive but not significant. The Organisational Commitment Questionnaire (revised) (OCQ) developed by Meyer and Allen (2005: 73) was used to measure employee commitment. Hypothesis 2 addressed the relationship between organisational commitment and turnover intention. The Pearson product-moment correlation coefficient between organisational commitment and turnover intention was r = 0.572 with a p-value = 0.065*, indicating a positive but not significant correlation. Hypothesis 3 addressed the relationship between perceived alternative job opportunities and turnover intentions. The Pearson product-moment correlation coefficient between perceived alternative employment opportunities and turnover intention was r = 0.953 with a p-value = 0.081*, indicating a positive but not significant correlation. It can be concluded that the correlation between the dependent variable and independent variables in the replicated study was positive but not significant which is consistent with the original study conducted by Rahman et al. (2008). The results reveal that in order for the participating organisation to be competitive in the 21st century a firm grip needs to be taken on reducing turnover intentions. Even though the correlation between the variables was not significant it supports previous studies that have found a significant correlation between job satisfaction, organisational commitment, perceived alternative job opportunity and its association with turnover intention. The replicated study will be presented to the participating organisation in an attempt to add value. The audience are managing executives and heads of departments, who are people that can make a difference within their respective divisions. When there is buy-in from top management, this will ensure that the need and urgency for retaining critical skills is filtered down to the lower levels. It will benefit the participating organisation that has a philosophy of wanting to continuously improve. It is recommended to the management of the participating company to pursue a retention strategy highlighting commitment and job satisfaction to obtain a committed and satisfied workforce through application of suitable human resource policies. These include training, career planning and advancement opportunities, employee participation and compensation plans to reduce employee turnover intention (Rahman et al., 2008: 79). By building a company’s business model around job satisfaction, organisational commitment and perceived alternative job opportunities, morale can be increased and commitment can be strengthened. When employees are satisfied they do not have the need to look for work elsewhere, which will contribute to a successful and competitive organisation.
177

Learners’ understanding and experiences of bullying at a primary school in the Western Cape

Johnson, Dawn Alice January 2014 (has links)
Thesis submitted in fulfilment of the requirements for the degree Master of Education in the Faculty of Education and Social Sciences at the Cape Peninsula University of Technology 2014 / This study aimed to determine learners' understanding and experiences of the different types of bullying and to examine the extent of bullying and roles they have been exposed to in various types of bullying. The research question was: What are primary school learners. understanding and experiences of bullying? Literature indicates that bullying can be executed in direct and indirect forms (Olweus, 1993:10; Boulton et al., 2002:354; Hunter & Boyle, 2002:324; Piskin, 2003:556; Lee, 2004:9). Direct bullying can be defined as relatively open attacks on a victim (Boulton et al., 2002:354) that are carried out face to face and may include pushing, kicking and fighting (Lee, 2004:10). Indirect bullying can be defined as being more subtle and less direct (Boulton et al., 2002:354) and will include behaviour such as social isolation and exclusion from a group. This study used the Olweus Intervention Method (1995), which offers a theoretical framework that could help the researcher find meaning in respect of the roles of the bully, victim and bystander. Urie Bronfenbrenner.s ecological theory (Bronfenbrenner,1998:993-1027) of human development was used as a lens for understanding bullying. Bronfenbrenner places child development within four different interacting levels, for example, the microsystem, mesosystem, exosystem and macrosystem (Sigelman & Schaffer, 1995:87). The researcher used a mixed-method research design as it could provide a better understanding of how learners understand their experiences of bullying . whether they were the victim, bully or witness. The total sample comprised 296 Intermediate Phase learners. The study began with a quantitative method, testing the understanding of concepts, and using a questionnaire for learners, and thereafter concluded with a qualitative method comprising a small number of learners (interviews with a focus group), exploring their experiences of bullying. The quantitative data was analysed by means of descriptive statistics to present simple summaries about the sample and the measures. The responses were recorded in frequency tables and percentages were calculated to determine general trends. The qualitative data was systematically organised into themes and patterns to bring meaning to the themes by telling a story. Information obtained from respondents was treated as highly confidential and the research findings were presented with integrity. The results indicated that most learners have not been exposed to bullying as victims, although a high number of incidences were reported. Older boys were mostly involved in incidences of physical violence. Of significance is the fact that the main kind of bullying was that of emotional bullying. Table 4.7 shows that mostly boys are teased (37.0%), while Table 4.16 shows teasing others mostly occurs between learners of the same age (30.4%). On the other hand, Table 4.17 reveals that mostly girls are prone to spread rumours about others (17.5%) of the same age as themselves (26%) and fall prey to this type of emotional bullying.
178

Comparison of diagnostic tools and molecular based techniques for the rapid identification of Escherichia coli and coliforms in contaminated river water

Ndlovu, Thando January 2013 (has links)
Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Environmental Health in the Faculty of Applied Sciences at the Cape Peninsula University of Technology, 2013 / Water is an important daily requirement and in a clean, pure form, it promotes health and well-being. In addition to South Africa being one of the driest countries in the world, water availability is also being compromised by massive pollution of remaining water sources. The Berg- and Plankenburg Rivers are two of the surface water sources in the Western Cape, South Africa, which are highly polluted by sewage, industrial and agricultural run-off. The current investigation was aimed at comparing diagnostic tools, which are employed by municipalities and food industries, and molecular based techniques to routinely monitor water for indicator organisms in time- and cost-effective manner. These rivers were sampled twice a month (July 2010 to January 2011) at the sites closest to the informal settlements of Kayamandi in Stellenbosch (Plankenburg River) and Mbekweni in Paarl (Berg River). The contamination levels of the two river systems were evaluated by the enumeration of Escherichia coli and coliforms using the Colilert 18® system, Membrane Filtration (MF) and Multiple Tube Fermentation (MTF) techniques. The highest faecal coliform count of 9.2 × 106 microorganisms/100 ml was obtained in weeks 21 and 28 from the Plankenburg River system by the MTF technique, while the lowest count of 1.1 × 103 microorganisms/100 ml was obtained in week one for both river systems by the MTF technique. The highest E. coli count of 1.7 × 106 microorganisms/100 ml was obtained from the Berg River system (week 9) using the MTF technique, while the lowest count of 3.6 × 102 microorganisms/100 ml was obtained by the MF technique from the Plankenburg River system. The coliform and E. coli counts obtained by the enumeration techniques thus significantly (p > 0.05) exceeded the guidelines of 2000 microorganisms/100 ml stipulated by the Department of Water Affairs and Forestry (DWAF, 1996) for water used in recreational purposes. Overall the results obtained in this study showed that the water in the Berg- and Plankenburg River systems is highly polluted, especially where these water sources are used for irrigational and recreational purposes. For the coliform and E. coli counts obtained using the three enumeration techniques, it was noted that the MTF technique was more sensitive and obtained higher counts for most of the sampling weeks. However, the media (Membrane lactose glucuronide agar) used in the MF technique also effectively recovered environmentally stressed microbial cells and it was also better for the routine selection and growth of coliforms and E. coli. While E. coli and total coliforms were detected utilising the Colilert 18® system, accurate enumeration values for these two indicator groups was not obtained for the entire sampling period for both river systems. It has previously been shown that dilutions (up to 10-3) of highly polluted waters increase the accuracy of the Colilert 18® system to enumerate colifoms and E. coli in marine waters. As the results obtained utilising the Colilert 18® system were also not comparable to the MF and MTF techniques it is recommended that highly polluted water samples be diluted to increase the accuracy of this system as a routine enumeration technique. Water samples were directly inoculated onto MacConkey, Vile Red Bile (VRB) agar and the Chromocult Coliform agar (CCA) and single colonies were inoculated onto nutrient agar. Chromocult coliform agar proved to be more sensitive than MacConkey and VRB agar for the culturing of E. coli and coliforms. Preliminary identification of these colonies was done using the RapID ONE and API 20 E systems. The most isolated Enterobacteriaceae species by both systems, included Klebsiella pneumoniae, Klebsiella oxytoca, Escherichia coli and Enterobacter cloacae in both river systems. The API 20 E system was more sensitive in the preliminary identification of the various isolates, as greater species diversity was obtained in comparison to the RapID ONE system. The Polymerase Chain Reaction (PCR) was firstly optimised using positive Enterobacteriaceae species. The optimised method was then applied to the analysis of river water samples, which were centrifuged to harvest the bacterial cells, with DNA extracted using the boiling method. The extracted DNA was amplified using conventional PCR with the aid of species specific primers. The Enterobacteriaceae species that were detected throughout the study period in both river systems include Serratia marcescens, Escherichia coli, Klebsiella pneumoniae and Bacillus cereus. Conventional PCR was the most reliable and sensitive technique to detect Enterobacteriaceae to species level in a short period of time when compared to RapID ONE and the API 20 E systems. Multiplex PCR was optimised using the positive pathogenic E. coli strains namely, Enteropathogenic E. coli (EPEC), Enteroinvasive E. coli (EIEC), Enterohaemorrhagic E. coli (EHEC) and Enteroaggregative E. coli (EAEC). It was then employed in river water sample analysis and enabled the detection of EAEC, EHEC, and EIEC strains in Berg River system, with only the EAEC detected in the Plankenburg River system. Real-time PCR was used to optimise the multiplex PCR in the amplification of E. coli strains and successfully reduced the time to obtain final results when using control organisms. Real-time PCR was found to be more sensitive and time-effective in the identification of E. coli strains, and also more pronounced DNA bands were observed in real-time PCR products compared to conventional-multiplex PCR amplicons. To sustain the services provided by the Berg- and Plankenburg Rivers in the Western Cape (South Africa), these water sources should frequently be monitored, results assessed and reported according to the practices acknowledged by responsible bodies. It is therefore recommended that the enumeration techniques be used in conjunction with the very sensitive PCR technique for the accurate detection of coliforms and E. coli in river water samples.
179

Current maintenance strategies of university building facilities in the Western Cape, South Africa

Simpeh, Frederick January 2013 (has links)
Thesis submitted in fulfilment of the requirements for the degree of Master of Technology: Construction Management (Facility Management) Department of Construction Management and Quantity Surveying In the Faculty of Engineering At the Cape Peninsula University of Technology, 2013 / Universities generally have low budgets for building maintenance and this reality, often aggravated by further reductions, results in a decline in the condition and performance of buildings. This particular research investigated the current building maintenance strategies of Cape Peninsula University of Technology (CPUT). The aim of the research was to develop improvement, prioritisation and involvement strategies to guide the maintenance of the performance parameters of the lecture theatres to ensure a performance level that meets the satisfaction of students, thereby promoting their learning experience. A mixed research design was used for the main study. A “case study” approach was adopted. CPUT was selected and three lecture theatres were selected as the cases for the research study. An exploratory study was carried out at the initial stage of the study, helping to formulate the research question and objectives for the main study. Observations, interviews and questionnaires were used to collect the primary data for the main study. A total of 430 questionnaires were distributed, out of which 283 representing a response rate of 65.8% were duly completed and returned. Importance Performance Analysis (IPA) model together with both descriptive and inferential statistics were used to analyse the data. The findings revealed that the performance of lecture theatres affects learning experience, and that all identified performance parameters were important to students’ learning experience. However, lighting, structural safety, ventilation and cleanliness were more highly ranked than fire safety & exit and aesthetics. It also became evident that, while all the performance parameters appeared to be underperforming, the performance of structural safety and lighting seemed satisfactory in all the lecture theatres, whereas ventilation, temperature, fire safety & exit (particularly old lecture theatres) and sound control were clearly underperforming. Furthermore, the study revealed that students are not involved in the maintenance management process of the lecture theatres whereas their involvement could ensure their satisfaction. Students perceived that instituting maintenance coordinators would be the most effective way of ensuring their involvement, followed by placing suggestion box in the department, or possibly organising forums at departmental level. To achieve better lecture theatre performance, the CPUT maintenance department needs to improve on the HVAC system (ventilation and temperature), fire safety & exit (particularly old lecture theatres) and sound control but without neglecting the other performance parameters. A further study to include teaching staff, additional lecture theatres and more parameters is highly recommended as it will provide a broader perspective to further help the CPUT maintenance department better maintain the lecture theatres.
180

Investigation of the application of IEC61850 standard in distribution busbar protection schemes

Mnguni, Mkhululi Elvis Siyanda January 2013 (has links)
Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Electrical Engineering in the Faculty of Engineering at the Cape Peninsula University of Technology Supervisor: Prof. R. Tzoneva Co-supervisor: Prof. P. Petev 2013 / Busbars are the most important components in the distribution networks. Faults on the busbar are uncommon, however an occurrence of a busbar fault can lead to a major loss of power. Busbars are the areas in a substation where the levels of current are high and therefore the protective relay application is very critical. In order for the protection scheme to be successful it is important to carry out the following specifications: Selectivity, Stability, Sensitivity, and Speed. To meet all of the above requirements protection must be reliable, meaning that the protection scheme must trip when called up to do so (dependability) and it must not trip when it’s not supposed to (security). The thesis focuses on the reverse blocking busbar protection scheme with aim to improve the speed of its operation and at the same time to increase operational reliability, flexibility and stability of the protection during external and internal faults by implementation of the extended functionality provided by the IEC61850 standard-based protective IEDs. The practical implementation of the scheme by the use of IEC 61850 standard communication protocol is investigated. The research analyzes in detail the reverse blocking busbar protection scheme that is used at the moment in the power systems and it develops an improved IEC 61850 based reverse blocking busbar protection scheme for a distribution network. The proposed scheme is designed for a radial type of a distribution network and is modeled and simulated in the DigSILENT software environment for various faults on the busbar and its outgoing feeders. The results from the simulations are used further for implementation of the designed protection scheme. A laboratory test bench is build using three compliant with the IEC 61850 standard ABB IEDs 670 series, CMC 356 Omicron test injection device, PC, MOXA switch, and a DC power supplier. Two ways of the reverse blocking signals between the IEDs implementation are considered: hard wired and Ethernet communication by using IEC 61850 standard GOOSE messages. Comparative experimental study of the operational trip response speed of the two implementation shows that the performance of the protection scheme for the case of Ethernet communication is better The thesis findings and deliverables will be used for postgraduate studies of other students, research, short courses, and solution of industrial problems. Keywords: Busbar, Power system, reverse busbar blocking scheme; IEC61850; Distribution, Protection relays, IEDs, GOOSE message, laboratory test bench

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