RS Power & Electric Transformer windings are made of high conductivity, electrolytic copper, pin hole free super enamels wire. The insulation material and wire are checked for any chemical reaction with transformer oil. All windings are vacuum dried and properly pressed & clamped before assembling. For the LV. Winding one or more copper insulated with pure cellulose paper or lather wet paper are used and for the H.V. winding one or more elementary copper strip or super enamel copper wire are used.