Title :
Estimation of the hottest spot temperature (HST) in power transformers considering thermal inhomogeniety of the windings
Author :
Pradhan, M.K. ; Ramu, T.S.
Author_Institution :
Dept. of High Voltage Eng.. Indian Inst. of Sci., Bangalore, India
Abstract :
The degradation of electrical insulation in transformers is traced to thermoelectric processes. Existence of localized hot regions due to thermal insulating properties of electrical insulation would cause thermal runaway around these regions. In an earlier paper , the authors presented analytical methods for estimating the temperature and its distribution at different points of the transformer based on a closed-form mathematical technique using a generalized heat conduction (GHC) model. Certain aspects of the inhomogeniety of the several components of the winding and incorporation of distributed heat source were not addressed. Also, a rigorous treatment involving the changes in winding resistance, which was built into the thermal model as an empirical correction factor, has now been modified and incorporated in the GHC. These considerations have now improved the accuracy of estimation of hottest spot temperature.
Keywords :
heat conduction; power transformer insulation; temperature measurement; thermoelectricity; transformer windings; distributed heat source; electrical insulation degradation; empirical correction factor; generalized heat conduction model; hottest spot temperature estimation; localized hot regions; power transformers; thermal insulating properties; thermal runaway; thermoelectric processes; winding thermal inhomogeneity; Cooling; Dielectrics and electrical insulation; Fourier transforms; Petroleum; Power transformer insulation; Power transformers; Temperature; Thermal conductivity; Thermal degradation; Windings; HST; Location of hottest spot temperature; prediction accuracy; transformer insulation; winding thermal conductivity;
Journal_Title :
Power Delivery, IEEE Transactions on
DOI :
10.1109/TPWRD.2004.835291
