HV windings of transformer coated with epoxy cast resin under vacuum. LV windings of the transformer can be produced by both cast resin and resin-impregnated prepreg methods.
They are produced in natural air-cooled (AN) or fan-cooled (AF) options in the 25-25000 kVA power range, up to 36 kV voltage level. It can provide up to a 40% power increase by using a cooling fan.
Dry-type transformer manufacturing requires advanced technology and knowledge, increases its market share compared to oil-type transformers with the increasing customer demands in recent years. In today’s technology, however, the production of large power dry-type transformers, especially above 36 kV voltage level, involves technological challenges. Research and development studies on this subject are continuing at full speed. No environmentally harmful coolant such as oil, less risk of fire, maintenance-free, resistant to moisture, can be commissioned at any time despite the fact that it is not in operation for a long time and can be loaded more than 40% of nominal power with fan cooling supplement oily type distribution transformers. However, the most important negative aspect of today is the higher sales price compared to an oil-type transformer of the same power, dry-type distribution transformers have been increasing the share of sales in recent years.