Question

A single phase transformer core, for use in a 50Hz electrical network, has the following magnetic characteristic Flux Density B Magnetic Field Strength H Total Core Loss 0.8 1.28 1.68 2.09297RMS Ampere-Turns/cm 1.23 1.85 2.2 2.73 Watts/k 1.0 1.1 1.2 Tesla The core has a cross-sectional area of 175cm2, the mean magnetic path length is 160cm and the density of the core material is 7.5gm/cm3. (a) If a no-load voltage ratio of 6600/231 is required, choose a suitable number of primary and secondary turns so that the maximum flux density in the core does not exceed 1.2 Tesla. [NB: E = 4.44?NM (b) Using these turns, calculate the no-load current and power factor at normal operating voltage. Note that you should allow an additional 50 Ampere-Turns to compensate the increased reluctance of the magnetic path resulting from gaps between "E and "I-sections" of the core laminations. Although your answer will be based on mathematical calculation, your results will require some interpretation and the application of engineering judgement before you reach a final answer. You should provide suitable written justification of your design decisions.

Answer 1

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LA 2 0

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