How Are Transformer Insulation Barriers Designed?
Quick answer — Insulation barriers (pressboard, crepe paper, angle rings and end rings) are designed to control the electric field and provide the dielectric path between the windings, leads and earth. Their thickness, position, radius and the creepage length are set so the stress is low and the risk of a partial discharge or flashover is minimal. The design uses the field and the creepage, with the barriers chosen for the voltage, the temperature and the mechanical duty.
How are the insulation barriers (pressboard) designed?
Their role
Barriers (pressboard, angle rings, end rings, lead exits) separate the windings and control the field, providing a dielectric path and a creepage distance.
Design factors
Thickness, position and radius set the local field; the creepage and the stress along and across the barrier are chosen to avoid a partial discharge or flashover.
Materials and duty
Pressboard (and aramid for high temperature) is selected for the voltage, temperature and mechanical duty, and the barrier is formed and dried to be compatible with the oil.
References & standards
- IEC 60641 (pressboard)
- IEC 60076-3
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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