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    E-lesson

    OLTC Course – e-lesson #7 – Analysis of OLTC test results

    OLTC Course - e-lesson #7
    Course: Master’s level

    Hosted by: Raka Levi / Master's level

    Analysis of results from dynamic test techniques applied to transformers with on load tap changers

    This OLTC course lesson on the master's level was presented by Dr. Raha Levy. The focus was on analyzing test results from dynamic testing of on-load tap changers (OLTCs). Dr. Levy explained how to evaluate numerical results like winding resistance, transition resistor values, and switching times. He also demonstrated how to analyze the shape and details of OLTC graphs, looking for consistency, irregularities, and indications of problems. Common OLTC issues like contact problems, mechanical issues, and control problems were discussed, with examples of how they manifest in the test data. The lesson covered interpreting vibration and acoustic analysis as well. Overall, the session provided a comprehensive overview of effectively diagnosing OLTC condition through dynamic testing and data analysis.

    This is the first e-lesson on the Master's level of the OLTC Course, but feel free to choose the level that suits your needs best.

    To see the entire syllabus, see the OLTC Course Brochure.

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    Learn about:

    • good / bad results
    • resistor type OLTC
    • reactor type OLTC
    • vacuum type OLTC
    • various failures detected using test methods

     

    Keywords: dynamic test results, diagnostics, resistor, reactor OLTC, preventive autotransformer

    About the author

    Raka Levi

    Raka Levi

    Dr. Levi spent his entire career in diagnostic testing transformers and other substation apparatus, while the last 15 years dealing with tap changers. He is senior member IEEE and vice-chairman of the working group for revision of Guide for testing power transformers. Raka Levi consulted clients on all 5 continents in the field of condition assessment and substation monitoring.

    Edis Osmanbasic

    Hitachi Energy

    Edis Osmanbasic is a Senior Project Lead Engineer for BESS and Microgrids at Hitachi Energy Sweden. His responsibilities are all technical aspects of the full BESS station from selecting main components to defining full system automation. Before this role, he was an Application and Testing Specialist at DV Power, Sweden for 14 years. His experience involves diagnosing transformer test results and defining and proposing maintenance strategies for HV equipment. His focus was developing test methods for condition assessment of transformers, OLTCs, and generators. Edis has published numerous papers on DRM methodology and transformer testing methods. He holds an MS in electrical engineering.

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