How Is Transformer Winding Temperature Monitored?
Quick answer — Winding temperature is monitored by winding temperature indicators (WTI) that use a sensor in a pocket heated by the oil (a thermal image of the hottest spot) or by measuring the oil temperature and adding a winding gradient, or by the winding resistance. It is used to control the cooling and the loading and to alarm before the hottest-spot limit is exceeded.
How is the winding temperature of a transformer monitored?
Oil and WTI
The oil temperature is measured directly; the winding temperature is derived by a winding-temperature indicator that simulates the heat gradient, giving a proximity to the hottest spot.
Fiber-optic (optional)
Optical sensors can be placed directly in the winding hottest-spot for a precise reading, useful on large or high-loaded units.
Using it
The winding temperature drives the cooling control (fans/pumps), the alarm and trip settings, and the loading policy, so it is critical for protecting the insulation life.
References & standards
- IEC 60076-7 (loading guide)
- IEEE C57.91
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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