What Is Stray (Eddy) Loss in a Transformer?
Quick answer — Stray loss is the additional loss from the leakage flux inducing eddy currents in the tank, the core, the leads and the metallic parts, on top of the winding and core loss. It rises with the load (and harmonics) and heats the tank and the metallic parts, causing hot spots and reducing efficiency. It is controlled by using non-magnetic/screened parts, conductive shields and by the design, and is part of the load loss.
What is stray loss and why does it matter?
What it is
The leakage field from the windings cuts the tank, core, leads and other metallic parts, inducing eddy currents that cause loss and heat.
Why it matters
It adds to the load loss (lowering efficiency) and can cause a hot spot in the tank or the clamps, so it is a design and a thermal concern.
How it is reduced
Use non-magnetic materials, conductive/amagnetic shields, and design the close metallic parts to reduce the flux, keeping the stray loss and the heating low.
References & standards
- IEC 60076-1
- IEEE C57.12.00
Related
Related manufacturers
Prolec GE (GE Vernova) · Prolec GE Waukesha · Hitachi Energy USA · Siemens Energy · Eaton · Virginia Transformer Corp
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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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