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Electrothermal analysis of large electric current systems by finite element method (유한요소법을 이용한 대전류 시스템의 전열해석 )
The electrothermal analysis by the finite element method can be applied to large current systems. Especially, using artificial interface elements, the electric contact resistance can be considered. A vacuum circuit breaker is one of large current systems. Because the heat generation by electric resistance in this system causes energy loss, overheating of the system must be prevented. To reduce the heat generation that caused by an electric resistance and a large electric current, the electric resistance, especially the electric contact resistance must be reduced. The contact resistance can be reduced by improving the surface flatness and cleanness. Through experiments and the finite element method, it can be known that serious heat by a large electric contact resistance generates in which component of the system. Then a modification of design of that component can prevent overheating. The spot welding is another large electric current system. Because stress concentration can be reduced in elliptic nuggets, elliptic nuggets must be studied. To get elliptic nuggets, elliptic electrodes must be used and relation between ellipcities and the nugget shapes must be studied. These relations can be calculated by the finite element method considering the temperature dependent thermal and electrical properties including the electric contact resistance and the latent heat effect.