What Is the Standard Temperature Rise of a Transformer?
Quick answer — The temperature rise is the highest temperature above the ambient the winding (and oil) can reach at rated load, set by the standard and the insulation class. A common rise is 65 K for the average winding (IEEE) and 60/65 K for the oil; IEC uses the insulation class limit. The rise is verified in the temperature-rise test and limits the loading to keep the insulation within its class.
What is the standard temperature rise of a transformer?
The rise and the class
The temperature rise (e.g. 65 K) is the increase above the ambient at rated load. The insulation class (A/B/F/H) sets the maximum hottest-spot, so the rise must keep the hottest-spot within the class.
IEEE vs IEC
IEEE commonly uses a 65 C rise (oil and winding), and IEC sets the rise by the insulation class and the cooling. The two differ in the basis and the convention.
Why it matters
The rise governs the loading and the insulation life, so it must be verified by the temperature-rise test and respected in service.
References & standards
- IEC 60076-2 (temperature rise)
- 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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