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In general, which is the phase relationship between the primary and secondary voltages of an ideal transformer? Does it depends on the dot convention?

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which is the phase relationship between the primary and secondary voltages

The dot convention tells you which terminals will have secondary and primary voltages in phase: -

enter image description here

Above picture from here. Consider also this picture of two identical windings wound the same way: -

enter image description here

For any secondary load current, the primary load current will be 180 degrees out of phase at the dotted terminals. Consider this picture for the current: -

enter image description here

Lower pictures from here. See also this answer for a wordy version of the above.

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  • \$\begingroup\$ Thank you, I have still another question. So, for analyzing circuits with a transformer with certain given dots, how should we fix the polarities of voltages and currents (with the load convention or source convention? and with respect to the dots?)? Is it an arbitrary choice, since then we will apply the rule "current before crossing the dot and then the inductor for both coils = + M, while if it happens for only a coil =-M"? \$\endgroup\$
    – Kinka-Byo
    Commented Jun 28, 2019 at 6:48
  • \$\begingroup\$ I'd say it's arbitrary; you can talk about primary voltage phase with respect to secondary or vice versa; there is no fixed rule about this. I wouldn't use the term current before crossing the dot because clearly that is also the current after the dot. \$\endgroup\$
    – Andy aka
    Commented Jun 28, 2019 at 9:07
  • \$\begingroup\$ Ok, thank you very much \$\endgroup\$
    – Kinka-Byo
    Commented Jun 28, 2019 at 9:43

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