電力設備中的絕緣材料會隨著時間、環境、人為等因素而產生老化現象，為了避免因絕緣劣化造成電力設備之突發性故障，可利用即時監測絕緣劣化之狀態，並預估其劣化趨勢與類型，防患於未然。
由於地下電纜常見的事故，大多數發生原因為施工人員在現場製作電纜接續部位不良所造成的瑕疵，電纜連接頭（joint）因現場施工產生的輕度瑕疵，多數無法於竣工試驗時被檢測出，在經過長期運轉後，瑕疵逐漸擴大並最終導致絕緣破壞。本文以「交連聚乙烯絕緣聚氯乙烯被覆電力電纜（XLPE）」直線接頭做為試驗對象，經由預先規劃兩種可能的瑕疵施作連接頭，定期每8小時增加2kV電壓直到絕緣擊穿為止。每次量測間隔4分鐘，擷取試驗電壓與部分放電電流訊號40 cycles，經過濾波和化簡後，從轉換資料的全週期與正、負半週中萃取出標準差、偏態、峰態、相位重心、起始相位、相位寬度、密集度等相關的26個特徵參數，並運用雙特徵值之轉折曲線進行絕緣狀態評估，選出較能代表絕緣狀態規則之特徵組合。最終本文以軌跡後期轉折處做為絕緣狀態的判斷依據。
這項研究旨在進行含有預設施作瑕疵的電力電纜之部分放電絕緣狀態試驗與分析由試驗獲得的放電資料以評估絕緣狀態。其瑕疵種類有「單邊內半導電層未搭接（絕緣層間隙）、中間空洞」兩種，每種瑕疵各有三個相同條件的試驗樣品，以獲得相同瑕疵之普遍特性的規則。

The insulating material of the electric apparatus can be aging with time, environment or artificial factors, etc. In order to avoid the insulating degradation that causes the sudden faults of the electric apparatus, we can monitor the condition of the insulating degradation immediately, and can estimate its trend of degradation and type in advance, prevent trouble before it happens.
Because of the common accidents of the undergrounded cables, most reasons are that the constructors make the cable joint bad at the scene. The cable joints had some slight defects at completion, but the majority is unable to be measured out while completion test. After operating for a long time, the defects were expanded gradually and caused insulation breakdown finally. In this thesis, we chose the direct joint of cross-linked polyethylene insulated polyvinyl chloride jacked cable (XLPE) as an experimental target, via planed two possible defect types, then make samples. We increase 2kV voltage fixedly until puncturing insulatingly every 8 hours. Each measurement recorded signal 40 cycles of the discharging current and voltage in every 4 minutes, after filtering wave and simplication. From the whole cycle, positive and negative part data, we can extract 26 characteristic parameters include the standard deviation, skewness, kurtosis, discharge phase weight, initial phase, the length of discharge phase region, the density of discharge phase region etc. We used the turn curve of a pair of characteristic value to assess the insulating status. Then we selected some characteristic associations they could represent the regular insulating status relatively. The final this thesis regards later period corner of the orbit as the judgement basis of the insulating status.
This thesis aims at doing test and analyzing data. Then in order to assess the insulating status of high voltage cables that involved two kinds of defects in advance. The two kind of artificial defects are below “Left a section of void between the joint insulation and the central conductor” and “Left middle cavity”. Each kind of defect had the three tested specimens of same condition respectively to obtain general characteristic of the same defect.

[1] 張建國，「地下電纜接頭部分放電線上監控系統之研製」，碩士論文，國立台灣科技大學，2006。
[2] 張建國，「高壓地下電纜接頭絕緣狀態之監測與診斷系統之研究」，博士論文，國立台灣科技大學，2012。
[3] 鍾易樺，「應用適應性類神經模糊推論系統於氣體絕緣開關瑕疵辨識之研究」，博士論文，國立台灣科技大學，2013。
[4] 周澤存 主編，高電壓技術，南京工學院，中國電力出版社。
[5] 潘彥竹，「部分放電量測系統之研製」，碩士論文，國立台灣科技大學，2004。
[6] 張智涵，「應用部分放電小波低頻成分於氣體絕緣開關之瑕疵辨識研究」，碩士論文，國立台灣科技大學，2012。
[7] 郭文慶，「用於15kV氣體絕緣開關瑕疵辨識之特徵參量選取研究」，碩士論文，國立台灣科技大學，2013。
[8] 鄭遠鐘，「適應性類神經模糊控制器於浦系統之應用」，碩士論文，國立中央大學，2000。
[9] 侯朝傑，「地下電纜接頭瑕疵之絕緣劣化分析」，碩士論文，國立台灣科技大學，2008。
[10] 何俊彥，「高電壓地下電纜接頭絕緣狀態即時性評估之研究」，碩士論文，國立台灣科技大學，2011。
[11] 周作謙，「應用失效率於高壓模鑄式比流器絕緣劣化之研究」，碩士論文，國立台灣科技大學，2007。
[12] 高電壓試驗技術－部分放電量測 High-Voltage test techniques－Partial discharge measurements. CNS 15175 C4500（IEC 60270）
[13] R. Bozzo, G. Coletti, and F. Guastavino, “Studies about the electrical treeing growth based on the evolution of the PD patterns,” IEEE Symposium on Electrical Insulation, Vol. 2, pp. 415~419, June 1998.
[14] M.S. Mashikian and A. Szatkowski, “Medium voltage cable defects revealed by off-line partial discharge testing at power frequency”, IEEE Electrical Insulation Magazine, Vol. 22, No. 4, pp. 24-32, July/ August 2006.
[15] H. Borsi, “A PD Measuring and Evaluation System Based on Digital Signal Processing”, IEEE Transactions on Dielectrics and Electrical Insulation, Vol 7, No.1
[16] S. Tokunaga, T. Tsurusaki, Y. Z. Arief, S. Ohtsuka, T. Mizuno * and M. Hikita, “Partial Discharge Characteristics till Breakdown for XLPE Cable joint with an Artificial Defects”, Proceedings of the 7th International Conference on Properties and Applications of Dielectric Materials June 1-5 2003 Nagoya.
[17] F. Guastavino and B. Cerutti, “Tree Growth Monitoring by Means of Digital Partial Discharge Measurement,” IEEE Transactions on Dielectrics and Electrical Insulation, Vol. 10, No. 1, pp. 65-72, February 2003.
[18] B. H. Ward, “Digital Techniques for Partial Discharge Measurement,” IEEE Transactions on Power Delivery, Vol. 7, No. 2, pp. 469-479, April 1992.
[19] E. Gulski, “Computer-Aided Measurement of Partial Discharge in HV Equipment,” IEEE Transactions on Dielectrics and Electrical Insulation, Vol. 28, No. 6, pp. 969-983, December 1993.
[20] Ruay-Nan Wu and Chien-Kuo Chang, “The Use of Partial Discharges as an Online Monitoring System for Underground Cable Joints,” IEEE Transactions on Power Delivery, Vol. 26, No. 3, July 2011.
[21] R. Bozzo, G. Coletti, and F. Guastavino, “Studies About the Electrical Treeing Growth based on the Evolution of the PD Patterns,” IEEE Symposium on Electrical Insulation, Vol. 2, pp. 415-419, June 1998.
[22] M. S. Mashikian and A. Szatkowski, “Medium Voltage Cable Defects Revealed by Off-Line Partial Discharge Testing at Power Frequency,” IEEE Electrical Insulation Magazine, Vol. 22, No. 4, pp. 24-32, July/August 2006.
[23] P. F. Gale, “Cable-Fault Location by Impulse-Current Method,” Proc. IEEE, Vol. 122, No.4, pp. 403-408, 1975.
[24] Barry Clegg, “Underground Cable Fault Location,” McGraw-Hill, 1993.
[25] N. Sarkar and B. B. Chaudhuri, “An Efficient Differential Box-Counting Approach to Compute Fractal Dimension of Image,” IEEE Transaction on Systems, Man and Cybernetics, Vol. 24, No. 1, pp. 115-120, January 1944.
[26] G. J. Paoletti and A. Golubev, “Partial Discharge Theory and Technologies Related to Medium-Voltage Electrical Equipment,” IEEE Transactions on Inductry Applications, Vol. 37, No. 1, pp. 90-103, January/February 2001.
[27] A. Kheirmand, M. Leijon, and Christer Tőrnkvist ABB Corporate Research/ Dept., “Detection and Localization of Partial Discharge in High Voltage Power Cable Joints” IEEE International Conference on Conduction and Breakdown in Solid Dielectrics, June 22-25 1998.