HV and LV windings are wound from copper /Aluminium conductors with polyesterimide enamel (Class B) insulation /DPC. The enamel covering conform to IEC 63017 Part -8. The windings are progressively wound (HV over LV) in single one piece rectangular/circular construction for better voltage regulation and mechanical strength. The inter layer insulation is of Epoxy Dotted Paper. Windings are done in clean atmosphere to prevent possible accumulation of dust particles. The coils are further automatic roller pressing windings machine, which improves bonding and short circuit withstanding capability. The provision of ducts in winding is made in order to control temperature gradient and rise for both winding & oil.
Windings can be made with Copper / Aluminium with Foil / Strip / Round wire of any combination to suit customer requirements. Accurately located taps and a large winding cross section keeps unbalanced ampere-turns create forces during short circuits that push the high voltage and low voltage and low voltage coils apart vertically. By minimizing the ampere –turn unbalance, vertical forces are correspondingly reduced, thus making the design stronger under short- circuit stresses. The large areas are presented by the layer-type winding result in a low ground capacity, which gives a nearly straight line surge distribution throughout the windings. All windings are checked and tested for all quality parameters and quality reports for windings & material characteristic data are maintained for verification.Next