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    Questions and Answers On Transformers

    Uploaded by

    Saber Abdelaal
    The document discusses questions and answers related to transformers. It covers topics like how magnetic leakage is reduced, factors that hysteresis loss depends on, how eddy current loss can be minimized, how changes in voltage and frequency affect transformer operation. For example, it states that interleaving the primary and secondary windings reduces magnetic leakage and that hysteresis loss depends on the quality and amount of iron in the core as well as the flux density and frequency.

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    Questions and Answers On Transformers

    Uploaded by

    Saber Abdelaal
    24 views2 pages
    The document discusses questions and answers related to transformers. It covers topics like how magnetic leakage is reduced, factors that hysteresis loss depends on, how eddy current loss can be minimized, how changes in voltage and frequency affect transformer operation. For example, it states that interleaving the primary and secondary windings reduces magnetic leakage and that hysteresis loss depends on the quality and amount of iron in the core as well as the flux density and frequency.

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    theraja q&a p3

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    The document discusses questions and answers related to transformers. It covers topics like how magnetic leakage is reduced, factors that hysteresis loss depends on, how eddy current loss can be minimized, how changes in voltage and frequency affect transformer operation. For example, it states that interleaving the primary and secondary windings reduces magnetic leakage and that hysteresis loss depends on the quality and amount of iron in the core as well as the flux density and frequency.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    24 views2 pages

    Questions and Answers On Transformers

    Uploaded by

    Saber Abdelaal
    The document discusses questions and answers related to transformers. It covers topics like how magnetic leakage is reduced, factors that hysteresis loss depends on, how eddy current loss can be minimized, how changes in voltage and frequency affect transformer operation. For example, it states that interleaving the primary and secondary windings reduces magnetic leakage and that hysteresis loss depends on the quality and amount of iron in the core as well as the flux density and frequency.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    of 2

    Questions and Answers on Transformers

    How is magnetic leakage reduced to minimum in commercial transformers?


    Ans. By interleaving the primary and secondary winding.

    Mention the factor on which hysteresis loss depends?


    Ans.
    • Quality and amount of iron in the core.
    • Flux density and the frequency.

    How an eddy current loss be minimized?


    Ans. By laminating the core.

    In practice, what determines the thickness when it's secondary open?


    Ans. Frequency.

    Dose the transformer draw any current when its secondary is open? Why?
    Ans. Yes, no load primary current.
    For supplying no-load iron and copper losses in primary.

    Is Cu loss affect by power factor? Why?


    Ans. Yes, Cu loss varies inversely with power factor.
    Because Cu loss depend on current in the primary and secondary windings. It's
    well known that current required is higher when power factor is lower.

    What affects are producer by change in voltage?


    Ans.
    1- Iron loss: varies approximately as V2.
    2- Cu loss: varies as V2 but decreases with an increase in voltage ((if constant
    KVA output is assumed)).
    3- Efficiency: for distribution transformers, efficiency at fractional loads
    decreases with increase in voltage while at full load or overload it increases in
    voltage and vice versa.
    4- Heating: for constant KVA output, iron temperatures whereas Cu temperatures
    decrease with increase in voltage and vice versa.
    5- Regulation: it varies as V2 but decreases with increase in voltage ((if constant
    KVA output is assumed.

    How dose changes in frequency affect the operation of a given transformer?


    Ans.
    1- iron loss: increase with a decrease in frequency. A 60-Hz transformer will
    have nearly 11% higher losses when worked on 50-Hz instead of 60 Hz.
    However, when a 25 Hz transformer is worked on 60 Hz, iron losses are
    reduced by 25%.
    2- Cu loss: in distribution transformers, it's depending on frequency.
    3- Efficiency: since Cu loss is unaffected by change in frequency, a given
    transformer efficiency is less at lower frequency than at higher one.

    Sharby2010@yahoo.com
    4- Regulation: at unity power factor is not affected because IR drop is
    independent of frequency. Since relative drop is affected, regulation at low
    power factors decreases with a decrease in frequency and vice-versa.
    5- Heating: since total loss is greater at a lower frequency, the temperature is
    increased with decrease in frequency.

    Sharby2010@yahoo.com

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