How can it be possible for doing the simulation of multi secondary(appx 40 nos) windings transformer with single primary considering all the effects of loading each secondary on primary & other secondaries?
The fundamental concept is called superposition. This is one of the critical basic concepts of all analog circuit analysis. I hope I only reminded you of an analysis tool you haven't used in a long time. If this is a new concept to you, you have a long road to travel to solve your question.
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"Don't disturb my circles." translation of Archimedes last words