How Are Transformer Insulation Materials Selected?
Quick answer — Select insulation materials by the required thermal class (A/B/F/H), the dielectric stress and clearances, the mechanical duty, and the compatibility with the insulating fluid. Kraft paper/pressboard for oil units, aramid and epoxy for dry-type, and DDP for interturn, are chosen so the insulation can withstand the temperature, voltage and mechanical forces while staying compatible and contaminant-free.
How do you select transformer insulation materials?
Thermal and dielectric
The material must be rated for the hottest-spot temperature (its insulation class) and withstand the dielectric stress at the clearances and the impulse level.
Mechanical and process
It must hold its shape under clamping and short-circuit forces, and be compatible with the winding process, drying and impregnation.
Compatibility with the fluid
The insulation must be compatible with the oil or ester and free of conductive particles and contaminants that could degrade the dielectric strength.
References & standards
- IEC 60085 (thermal classification)
- IEC 60641 (pressboard)
- IEC 60763 (laminates)
Related
Related manufacturers
Prolec GE (GE Vernova) · Prolec GE Waukesha · Hitachi Energy USA · Siemens Energy · Eaton · Virginia Transformer Corp
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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