本論文探討穿越市區中之地下電纜輸電線路電力頻率磁場分佈情形，分析磁場可能偏高原因並提出改善對策。從一個實際案例的測量結果中，分析出磁場偏高原因為地下電纜管路埋設遇障礙物，造成管路排列及埋設深度改變所致。故從探討地下電纜埋設深度、管路相序排列及金屬板屏蔽三種改善方法中，獲得以金屬板屏蔽磁場之方法具較佳改善效果。本論文也利用 FLUX3D電磁數值分析程式，建立地下電纜屏蔽架構，模擬各種不同屏蔽板形式對磁場屏蔽效果之影響，並探討屏蔽施工上需考量之因素。經由模擬與實測結果顯示，以提出之ㄇ型屏蔽架構改善效果較佳，所提出的方法實際應用於改善地下電纜磁場後，確實獲得抑低磁場之成效。

The purpose of this thesis is to study the distribution characteristics of power-frequency magnetic field of underground cables when transfer the power through urban area, to analyze the reasons of high magnetic field and to propose the improvement methods. From the results of measurement in a practical case, the reason of high magnetic field is the burying problems of underground cables when they contact barriers. Thus, the arrangement and depth of cables were changed. Therefore, this thesis discusses how to reduce magnetic field using three methods: the depth of underground cables, the arrangement of cables, and shielding methods. It is to obtain the shielding approach of metal plates as the proper improvement method. In this thesis, the FLUX3D simulation tool is utilized to establish the shielding model of underground cables, compare different frames of shielding and shielding results, and consider the causes of construction. The results of simulation and measurement show that the shielding model of ㄇ type is the proper method, and is propose to improve the magnetic field of underground cables. It really has the effect in reduction of magnetic field.

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