A Simple Model for Calculating Transformer Hot-Spot Temperature
ABSTRACT A simple model for calculating the hot-spot temperature is introduced. The model is based on the hot-spot to ambient gradient. The model considers the changes of the oil viscosity and winding losses with temperature. The results are compared with temperatures calculated by IEEE Annex G method and measured results at varying load for the following transformer units: 250-MVA ONAF, 400-MVA ONAF, and 605-MVA OFAF.
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ABSTRACT: High frequency transformers, used in switching power supplies, carry high amount of current. High frequency effects like skin, proximity and edge effects are discussed in this paper. Multi stranded or litz wires are used for reducing skin effect, but it will be shown that they are not effective in transformer normal winding. Paralleled interleaved winding is presented for reducing the high frequency effect. Two dimensional simulations based on finite element method are done for investigation of current distribution in high power, high frequency transformers.Energy Procedia 12:656–661.
Conference Paper: Numerical Analysis of Winding Temperature Field for Dry Type Transformer[Show abstract] [Hide abstract]
ABSTRACT: On the base of analysis winding characteristics for a dry type transformer, the simplified model of winding temperature field is established. Then, the winding temperature field is calculated by using finite volume method (FVM) and its distribution rules are analyzed and obtained. Finally, validation of hot pot temperature is confirmed by comparison of both calculating and testing result.Electromagnetic Field Problems and Applications (ICEF), 2012 Sixth International Conference on; 01/2012
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ABSTRACT: This paper gives a summary of the requirements and calculating methods for the maximum insulated conductor temperatures (usually referred to as hottest-spot temperature or hot spot temperature) in oil-immersed transformers. Laboratory experiments were performed on a 5 kV, 100 kVA transformer using thermocouples during the short circuit heat run tests, and the measurements from the tests are employed to compare some of the methods mentioned in the paper.01/2010;