Hi, I read this about Shell type transformers;

What does this exactly mean: "The primary and secondary windings are wrapped one on top of the other with the low-voltage winding innermost?" By low-voltage winding, do they mean the secondary one? And what do they mean by innermost here?

Also, what problem are they referring to in point a?

Help would be appreciated.

 

It has always been my experience that winding wound on top of each other the primary is the first one wound, (inner)?
Max.

 

It would apply to the large transformers used at power stations. why insulate for 1 million volts when you dont have to.

 

I see. Thanks for clarifying, but how is this accomplished? Like, how does the low-voltage winding insulate the high-voltage winding?

 

Just thinking in general terms, if you wrap wire around a laminated core then you have some chance of damaging the windings over time due to vibration if nothing else. Also, the insulation between the wire and the core is just the thickness of the insulation on that one wire plus the lamination thickness. But if you wrap wire around in existing winding, then the inner winding provides a cushion for the outer winding plus now you have the thickness of the insulation on both wires separating the two wires and even more separating it from the core itself.