The low voltage winding of the transformer is placed near the Cox in order to Reduce the cost of insultation and the size of the transformer. The insulation is directly proportioned to the voltage so, if the high voltage winding of the transformer is placed near the cox, the insultation would have to be thicker which heads to high cost. Placing the Hv winding after the Lv winding makes the much lesser thickness of the insultation for the Hv winding.