How Is a Dry-Type Transformer Designed?
Quick answer — A dry-type transformer has no oil, so the windings are insulated and cooled by air (or cast in epoxy/resin for a cast-resin type). The design must size the insulation (class B/F/H), the creepage and clearances, the airflow and cooling, and the short-circuit strength, with a higher temperature-rise limit and a larger footprint than an oil unit. Cast-resin and VPI windings are the two main styles.
How is a dry-type transformer designed?
Insulation and class
The insulation is class B, F or H (up to 155/180 C), using epoxy, aramid or polyester, so the temperature-rise limit is higher than oil-filled. The clearances and creepage must be large for air.
Cooling and size
Air cooling is less effective, so the windings and enclosure are larger, and the design must provide good airflow and minimise barriers that trap heat.
Winding style
Cast-resin (epoxy-encapsulated) or VPI (resin-impregnated) windings; the choice depends on the environment, the rating and the manufacturer.
References & standards
- IEC 60076-11 (dry-type)
- IEC 60076-2
Related
Related manufacturers
Prolec GE (GE Vernova) · Eaton · Virginia Transformer Corp · Delta Star · WEG Transformers USA · LS Electric America
Related components
Technical content is prepared from engineering references, standards frameworks, manufacturer documentation and industry sources. Contractual or compliance decisions should refer to current official standards. TransformerPath Technical Editorial.
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