Farady transformer uses lots of turns of thin wire

If your farady transformer 400kva uses lots of turns of thin wire, you are about ready to start farady three winding transformer at this point. But if it uses a winding that has few turns of a thick wire, you should check how well (or how poorly) that wire fits in an integer number of layers, considering the width of the bobbin, and about 5% of lost space due to the wire not being perfectly straight. The problem is this: If the sheet calculates you need 48 turns of a certain wire size, and it happens that you can fit only 15 turns per layer, then you will end up with three complete layers, plus one additional layer in which you have just three turns! So the total height taken up in the window by those 48 turns will be as much as 4 complete layers, that could have 60 turns! Consequently, the winding might end up too high, and won't fit the window! Then you cannot assemble the core, and you have to unwind that winding, throw the wire away, get new (thinner) wire, do it again