DRY TYPE TRANSFORMERS

The cooling method differs from oil-immersed transformers. HV windings are vacuum-coated with epoxy cast resin. LV windings can be manufactured using both cast resin and resin-impregnated prepreg methods.

They are manufactured with natural air cooling (AN) or fan cooling (AF) options for power ranges of 25-25,000 kVA and voltages up to 36 kV. Up to 40% power increase can be achieved by using a cooling fan.

Dry-type transformer manufacturing, which requires advanced technology and knowledge, has been steadily increasing its market share compared to oil-immersed transformers in recent years due to increasing customer demand. However, with today’s technology, the production of large-power dry-type transformers, especially above 36 kV, presents technological challenges. Research and development in this area continues at full speed. They are preferred over oil-immersed distribution transformers due to their lack of an environmentally hazardous coolant like oil, their lower risk of fire, their maintenance-free nature, their resistance to humidity and moisture, their ability to be restarted without any problems even after extended periods of inactivity, and their ability to handle overloads of up to 40% of nominal power with the added benefit of fan cooling. However, dry-type distribution transformers, whose most significant drawback is their higher sales price compared to an oil-immersed transformer of the same power, have been steadily increasing their sales share in recent years.