A three-dimensional eddy current field model for calculating the eddy current losses in an air insulated bus duct system is proposed. The temperature rises are evaluated using the coupled fluid field and the thermal field model. Good agreement between the computed and test results confirms the proposed methodology is a viable approach to the study of practical system.

Abstract-The transient eddy current fields are short-circuit forces upon the coils of large power transformers are analyzed. The proposed approach is based on the A-V-A formulation in which the eddy current field and the electric circuit equations are solved simultaneously. The effectiveness of a magnetic bypass plate near the coils ends for reducing the eddy current loss and the local overheating is discussed. A simulation to study the transient short-circuit behavior of a 720-MVA power transformer using the proposed coupled approach is reported.

In this paper, a three-dimensional eddy-current field model for calculating the eddy-current losses in a compact bus duct system is proposed. The temperature rises in the compact bus duct system, including both the long linear section and connecting unit, are evaluated using finite-element method when solving the governing thermal equations. The contact resistance between copper conductors and the corresponding temperature rises are measured in the test also. The computations are validated by test results and the results confirm the proposed algorithm is accurate and practical.

The 3-D open boundary eddy current field induced by heavy current flowing in the coils and winding leads in large power transformers is calculated. The eddy current loss and local overheating problem in the tank wall and in the ascending flange of bushings are analyzed and reported in this paper. The effectiveness of a magnetic bypass plate near the coil ends for reducing the eddy current loss and local overheating in the clamp plates is discussed.

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