Core Type Transformer Basic Construction

We are going to see about construction of Three phase core type transformer.
Main part of the transformer are core and winding This core is nothing but the laminated silicon steel sheets.
For three phase transformer the core is in the shape of digital eight and over each vertical each phase will have LV winding near to core and next to that hv Winding.
Here mostly we are going to see two main things.
1. Why we use core lamination?
2. Why we make lv winding near to Core side first and then hv winding?

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why WTI CT placed in B phase? what is the reason? and how to calculate the magnetizing current test (open circuit test) for 3 phase trafo