Abstract:This thesis is the result of conducting an analysis to find the solution to the phenomenon of power stoppage due to the disconnection of a CT (Current Transformer) because of vibration. The CT which measures the most essential current is used in power industries as part of a generator protection relay. When it comes to the bottom plate of a CT, nonconductor; such as bakelite and laminates; these material elements should be used because it is impossible to utilize the conductor when measuring the current of a generator which carries a high current if you use other materials. These nonconductor's material properties are irregular and interpretation errors often occur because the weight is light. In addition, since the change of dynamic characteristics which are related to the temperature often occur, it is important to match the real situation by considering an error of interpretation rather than selecting the quality of the material. Lastly, the conclusion that the study drew is that it is possible to avoid the resonance by utilizing three changes to the components to solve the problem concerning the high vibration which is caused by non-conductive objects. These changes are the most crucial points in this thesis: First, material changes to the Plate. Second, weight changes to the Coil. Third, thickness changes to the Plate.
조철환(교신저자) : 한국전력 전력연구원
Due to the serious imbalance of the secondary load of traction transformer, the negative-sequence current in the three-phase side is large, which inhibited the development of the technology of taking power from traction network. The negative-sequence current characters of power transformer for railways of five connection types by symmetrical component method, including D,y11, D,d0, Y,y0, Y,d11 and Reverse-Scott is discussed in this paper. Moreover, an improved Reverse-Scott connection type is proposed to reduce the unbalanced degree.
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