DocumentCode :
3597636
Title :
Asymmetry During Load-Loss Measurement of Three-Phase Three-Limb Transformers
Author :
Escarela-Perez, Rafael ; Kulkarni, S.V. ; Kodela, N.K. ; Olivares-Galvan, Juan C.
Author_Institution :
Univ. Autonoma Metropolitana, Mexico
fYear :
2007
Firstpage :
1
Lastpage :
1
Abstract :
Summary form only given. When the load-loss measurement test is conducted on three-phase transformers, an appreciable asymmetry is observed among the power readings of the three phases. This asymmetry is the result of two causes, viz. asymmetrical disposition of phases in space with respect to each other and unequal stray losses produced by phases. The disposition of phases leads to asymmetrical mutual impedances between phases and this is the principal contributor to the phenomenon. Another factor that may have an important contribution to the phenomenon is the deviation of the phase angle difference between the voltages of the three phase source (used during the test) from 120deg. The causes are analyzed using a detailed three-dimensional (3D) finite-element (FE) simulation of a 31.5 MVA, 132/33 kV transformer. In addition, a six-port network impedance model is deduced from open-circuit 3D FE simulations. The impedance model is able to reproduce any condition of the transformer (e.g. open-circuit, short-circuit or on-load conditions) since it captures all the transformer electromagnetic phenomena. The six-port network results are discussed in order to elaborately clarify the intriguing problem of asymmetrical load-loss distribution, which is important for both transformer manufacturers and users. The results are further explained through sequence components of currents.
Keywords :
finite element analysis; losses; power transformers; apparent power 31.5 MVA; asymmetrical load-loss distribution; asymmetrical mutual impedances; asymmetrical phases disposition; load-loss measurement; power readings asymmetry; six-port network impedance model; three-dimensional finite-element simulation; three-phase three-limb transformers; transformer electromagnetic phenomena; voltage 132 kV; voltage 33 kV; Analytical models; Electromagnetic modeling; Finite element methods; Impedance; Iron; Manufacturing; Phase measurement; Phase transformers; Power measurement; Testing;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Power Engineering Society General Meeting, 2007. IEEE
ISSN :
1932-5517
Print_ISBN :
1-4244-1296-X
Electronic_ISBN :
1932-5517
Type :
conf
DOI :
10.1109/PES.2007.386017
Filename :
4275783
Link To Document :
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