actually those big transformers are placed in normally so they need a high level of insulations. Thats the principle we use insulation anyway your question is kinda different. Well see in every core materials all the principles are same whether it is big or small but in more winding materials internal flux is more so may the transformers you have observed are having wire insulation but its not compulsory they are used only reduce internal flux in winding we need mutual flux for transfer of current but these internal flux create vibrations and cause for damage of insulation. Effect of those flux will be low in small transformers because of less windings. But one thing insulations costs more than winding. Cost is also factor in design of transformers
Correct me if i am wrong

narayana murthy

actually those big transformers are placed in normally so they need a high level of insulations. Thats the principle we use insulation anyway your question is kinda different. Well see in every core materials all the principles are same whether it is big or small but in more winding materials internal flux is more so may the transformers you have observed are having wire insulation but its not compulsory they are used only reduce internal flux in winding we need mutual flux for transfer of current but these internal flux create vibrations and cause for damage of insulation. Effect of those flux will be low in small transformers because of less windings. But one thing insulations costs more than winding. Cost is also factor in design of transformers
Correct me if i am wrong

Sir the concept you share is highly dense and thanks for sharing it

But sir I want to know if electromagnetic solenoid made of naked wire can work or it will behave as short circuit as theoretically current will choose less resistance path so it should not go circular around solenoid path (path 2 in fig) and should go above the solenoid surface making a straight path(path 1 in fig) ….
And sir obviously the path 2 is needed so sir how it is achieved in that I explained case of small transformer of naked wire winding ?

first of all don't call me sir. next i want to say is there is difference between resistance and inductance. so i think in transformers they don't bother much about self inductance in small transformers as no of turns is low mutual inductance is higher than self inductance. yes you are right this may make difference with insulation but see insulation costs 40% higher than copper so it makes difference in business. small amount of leakage is not an issue for that. i am not an expert in this i am just saying my reason

narayana murthy

first of all don't call me sir. next i want to say is there is difference between resistance and inductance. so i think in transformers they don't bother much about self inductance in small transformers as no of turns is low mutual inductance is higher than self inductance. yes you are right this may make difference with insulation but see insulation costs 40% higher than copper so it makes difference in business. small amount of leakage is not an issue for that. i am not an expert in this i am just saying my reason

Ok friend you want to say that for small scale machines resistance is neglected so current will flow throughout the coil without the requirement of any insulation between turns with compromise of small leakage right? Ok got your point

But obviously the value of flux produced will be less then NI due to leakage as you mentioned which is neglected then for just interest can you tell me any practical or logical method to design such small coils even when we don’t get the desired value of flux according to no of turns.

Will it behave as short circuit and go above the solenoid surface making a straight path (path 1 in fig)?

No. If the coil you made is sturdy and looks exactly as in the figure, even with no insulation, the coil will act as a perfect solenoid. Current will be taking 'path 2' shown in the figure when energised. Note that, it is assumed the coil is really sturdy and two adjacent windings do not touch each other. There won't be any kind of leakage current between two adjacent windings either. It simply will act as a perfect solenoid.

If the coil is made of bare conductor and two adjacent windings touch each other, the case will be different. the whole thing will act as a hollow conductor then and current will choose 'path 1' as shown in the figure.

By the way, in transformers, conductors used for winding are insulated, be it small or big. There is a thin coating of transparent insulation over the conductors used in miniature transformers you see.

To test it, use a multimeter and perform a continuity test on the conductor. You'll see that the test fails. Now remove the insulation by bringing the conductor in a flame or simply scrap off the insulation with some sharp objects like a blade and perform the test again. When you scrap the insulation off, you can even see a change in the colour of that scrapped part.

As far as I know , the wires used in small transformers are not actually completely naked wires, they are called Varnish Insulated wires.
This kind of wire is also used in fans.
Below is the figure , the wires appear to be naked but they are not.


Sorry If I have understood your question incorrectly.