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When a real transformer is modeled to a simpler circuit, it is shown that the core resistance or a resistance model which basically describes eddy current and hysteresis loss is in parallel with the ideal primary winding part. Why is that resistance considered in parallel instead of series? I know that the hysteresis loss and eddy current depends on the flux of the primary winding but what does it have to do with the parallel orientation?

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  • \$\begingroup\$ MSKB if we are done here, please take note of this: What should I do when someone answers my question. If you are still confused about something then leave a comment to request further clarification. Also note that your latest question has been closed to it being almost a carbon copy of this one. However, if you can explain why in comments that it should stand on its own then I'll vote to reopen it. If necessary I will amend my answer here for any issues arising in your newer question that were not covered here. I'll add one now. \$\endgroup\$
    – Andy aka
    Nov 30, 2023 at 20:27

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Why is that resistance considered in parallel instead of series? I know that the hysteresis loss and eddy current depends on the flux of the primary winding but what does it have to do with the parallel orientation?

Both eddy currents and core flux are proportional to the applied voltage and, are \$\text{not-at-all}^1\$ dependent on the secondary load currents or the primary referred secondary load currents hence, there is absolutely no alternative other than to model them as parallel components (so that they get worse with a bigger primary voltage and, are largely unaffected by primary or secondary load currents).


\$\text{not-at-all}^1\$ is a little to convenient to say when it comes to core flux and associated components. In fact, as the load current increases, the voltage appearing on the components \$R_C\$ and \$L_M\$ slightly reduces and, this slightly alleviates the problems associated with core saturation and eddy currents. Equivalent circuit from my basic website: -

enter image description here

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