Theses and Dissertations (Power Engineering)

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Browsing Theses and Dissertations (Power Engineering) by Author "Le Roux, B. J."

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    A testing and verification protocol for a modern bus bar transfer scheme based on the transfer philosophy and theory of voltage decay
    (Vaal University of Technology, 2020-04) Van Rooyen, Johannes Petrus; Le Roux, B. J.; Walker, J. J., Prof.
    This dissertation focuses on the creation of a testing protocol or procedure for verification of a modern motor bus bar transfer scheme. There are four main transfer methods addressed during this study and with it the main parameters affecting the operation of such a system. The complete construction of the simulation and training panel is described and with it the outline of the testing protocol for using this panel is given. Some simulation work was done to calculate the correct verification times based on mathematical formulation to lay out the criteria for verification of transfer methods when testing with a modern three phase test bench. On completion of result documentation, a detailed analysis is conducted to generate the testing protocol which is also discussed in detail. From the test results obtained it was possible to accurately test the 4 common transfer methods using the theory of voltage decay as a guideline, but the protocol will have to be adjusted to suit individual transfer system needs as each transfer system may be unique in design and function although the basic principles outlined during this report will stay the same. Possible steps to take when adjusting the protocol were addressed and some future work for testing motor bus bar transfer schemes was suggested.
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    Partial discharge evaluation of a high voltage transformer
    (2015-02) Kyere, Isaac Kwabena; Walker, J. J.; Le Roux, B. J.
    This dissertation is devoted to the study of partial discharge evaluation of a high voltage transformer. The 400 V/300 000 V (300 kV) high voltage transformer in the high voltage laboratory was manufactured in 1967. Given the old age of the transformer and the crucial importance of insulation systems, it is vital to assess the condition of its insulation to ensure the effectiveness and the reliability of the transformer as well as the safety of the personnel using it. In order to achieve that, it is important to evaluate the partial discharge in the insulation system as this is the main cause of destruction of insulation. The phase-resolved partial discharge method was the main method used to perform the partial discharge measurements in this research. Partial discharge measurements were performed on a faulty 11 kV voltage transformer. Defects were also created in samples of solid insulation at predetermined locations with different shapes and sizes. The measurements taken on the 11 kV voltage transformer and samples of solid insulation formed a basis to prove the validity of the assessment methods on the 300 kV transformer. Using the method mentioned above, partial discharges were recorded with respect to the phase of the applied voltage with the aid of a commercial instrument which complies with IEC 60270, (ICM monitor - partial discharge detector from Power Diagnostix Systems GmbH). The observations from this study have furthered the understanding of partial discharge processes. The patterns recorded were analysed in order to conclude about the condition of the transformer. From the partial discharge pattern, the type and location of partial discharges were concluded. The patterns obtained from the transformer reveal that the device is healthy and can be operated up to 200 kV.