What Is Core Annealing?
Quick answer — Core annealing relieves the stress in the grain-oriented electrical steel caused by cutting and laminating, so the magnetic properties (low loss and high permeability) are restored. The laminations are annealed in a controlled atmosphere furnace at the right temperature, then coated to insulate them. Good annealing keeps the magnetic domains aligned and the loss low.
Why is the transformer core steel annealed?
Why anneal
Cutting and processing introduce stress into the grain-oriented steel, degrading its magnetic properties; annealing relieves it so the loss and the permeability are restored.
The process
The laminations are annealed in a controlled (reducing) atmosphere at the right temperature and time, then insulated and cooled.
Why it matters
A correctly annealed core has low loss and high permeability; poor annealing raises the losses and the magnetising current.
References & standards
- IEC 60404 (electrical steel)
- IEC 60076-1
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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