By winding material, you mean winding conductor material and winding insulating material.

Winding Conducting Material: Winding conductor is made of copper. If it is aluminium winding transformer, it is mentioned specifically on the name plate. If nothing is mentioned about material of winding conductor, it must be copper.

Winding Insulating Material: If the transformer is oil filled, it is known easily because it is housed in a tank having conservator, breather etc. Also, the name plate will mention “insulation class A” meaning maximum permission temperature 105 °C. In such a case, insulation is cellulose based paper and pressboard impregnated with transformer oil.

If transformer is dry type, insulation is “class F”. Then the insulation consists of materials like glass, mica, epoxy resin in various forms.

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