Journal ArticleDOI
An investigation of the thermal performance of an oil filled transformer winding
TLDR
In this article, a comprehensive test program was performed using a winding assembly with embedded thermocouples, and steady-state and transient tests were performed for natural and non-directed forced oil calculation.Abstract:
Manufacturers may be required to design transformers to overload specifications. Oil viscosity changes and loss variation with temperature are not accounted for in the industry loading guide. A comprehensive test program was performed using a winding assembly with embedded thermocouples. Steady-state and transient tests were performed for natural and nondirected forced oil calculation. The temperature distribution in the winding was not linear with height as usually assumed. A large number of temperature sensors is required to determine the hot spot location. The location of the hot spot was found to be different and less predictable for natural oil calculation than for nondirected forced oil circulation, especially during overload conditions. Improved loaded guide equations were developed to account for oil viscosity, resistance change, cooling duct oil rise and location of the hot spot. >read more
Citations
More filters
Journal ArticleDOI
Dynamic thermal modelling of power transformers
TL;DR: In this article, the authors introduce hot-spot and top-oil temperature thermal models for more accurate temperature calculations during transient states based on data received in a normal heat run test (i.e., the top oil in the tank of the transformer and the average winding-to-average oil gradient).
Journal ArticleDOI
Transformer Design and Optimization: A Literature Survey
TL;DR: In this article, the authors conduct a literature survey and reveal general backgrounds of research and developments in the field of transformer design and optimization for the past 35 years, based on more than 420 published articles, 50 transformer books, and 65 standards.
Proceedings ArticleDOI
Predicting liquid filled transformer loading capability
TL;DR: The IEEE Transformer Loading Guide equations use the top oil temperature rise over ambient to determine the winding hottest spot temperature during an overload as mentioned in this paper, which results in winding hottest spots temperatures greater than predicted by the current (1981) IEEE Loading Guide equation.
Journal ArticleDOI
Dynamic thermal modeling of power transformers: further Development-part II
D. Susa,Matti Lehtonen +1 more
TL;DR: In this article, the authors present new temperature calculation methods based on heat transfer theory, the application of the lumped capacitance method, the thermal-electrical analogy, and a new definition of nonlinear thermal resistances at different locations within a power transformer.
Journal ArticleDOI
A new method for the calculation of the hot-spot temperature in power transformers with ONAN cooling
Zoran Radakovic,K. Feser +1 more
TL;DR: In this paper, an original thermal model of transformers with ONAN cooling was developed, which takes into account the influence of nonlinear thermal characteristics in transient thermal processes; instead of exponential functions and time constants, the numerical solution of differential equations is used.
References
More filters
Journal ArticleDOI
Effect of oil viscosity on transformer loading capability at low ambient temperatures
J. Aubin,Y. Langhame +1 more
TL;DR: In this article, a practical calculation method based on the bottom-oil temperature and the surface temperature at the top of the cooling duct has been developed for calculating the overload capacity for ambient temperatures below 0 degrees C or for severe overloads.
Journal ArticleDOI
Oil-Immersed Power Transformer Overload Calculations by Computer
John H. Blake,Edward J. Kelly +1 more
TL;DR: In this article, the application of overload ratings to power transformers is considered in the light of 30 years of operating experience and a comprehensive description of the philosophy of overloading, methods of calculation, transformer life curves, and a working computer program which incorporates these factors with increased accuracy and reduced engineering time.
Journal ArticleDOI
Emergency overloading of air-cooled oil-immersed power transformers by hot-spot temperatures
V. M. Montsinger,P. M. Ketchum +1 more
TL;DR: In this article, the authors show that during the period of the war the need for obtaining maximum transformer overload capacity is very great, particularly under rare emergency conditions, and that the amount of overload is limited by the hottest spot in the transformer winding.
Related Papers (5)
A fundamental approach to transformer thermal modeling. I. Theory and equivalent circuit
G. Swift,T.S. Molinski,W. Lehn +2 more