隨近年各國政府發展永續綠色能源及電動運輸載具，電力系統成為了重要的基礎建設，在這之中若發生非預期性的停機事故都會面臨重大的成本損失。在輸配電線路系統中，地下電纜線接續處常發生絕緣失效事故，因此線上局部放電量測已成為診斷電力設備絕緣狀態的重要預防方式。
本研究建立了局部放電等效電路模型，藉此探究模擬實際局部放電的放電路徑，並配合實際運轉環境，設計可抑制外部雜訊高頻比流器與差動式類比訊號處理電路，由微控制器取樣量測數據，供後續絕緣診斷分析即時判斷電纜線絕緣狀態，達到提早預防性維護之目的。
試驗中被試物由兩組直線接頭組成，一組為正常工法，一組含有人工空隙瑕疵，進行施加額定電壓、電流、加速劣化三種試驗，由類 比式差動量測法與數位式脈衝電流量測法做為對照，最後根據兩種絕緣診斷規則判定結果，進一步得出類比式差動量測法具備排除電纜電流感應信號和外部來源的局部放電、以及其他雜訊干擾之特點與可用於線上量測之優勢。

With the development of sustainable green energy and electric transportation vehicles by governments in recent years, the power system has become an important and basic infrastructure. In the event of unexpected shutdowns, it results in significant cost losses. Insulation failure accidents most often occur at the junctions of underground power cable lines in transmission lines. Therefore on-line partial discharge measurement has become an important preventive method for diagnosing the insulation status of power equipment.
In this study, a partial discharge equivalent circuit model is established, thereby investigating the discharge path to simulate the actual partial discharge. In accordance with the actual operating environment, a high-frequency current transformer and differential analog circuit are designed for noise suppression. The measurement data are sampled by the microcontroller and the insulation diagnosis data are provided to engineering personnel to determine the insulation status of the cable immediately. This measure will achieve the purpose of preventive maintenance.
In the test, two sets of cable joints are used as the test object, one set is the normal construction method, and the other set contains artificial void defects. According to a comparison between the analog inductance differential measurement method and the digital pulse current measurement method, three tests are conducted with rated voltage, current, and accelerated degradation. Finally, based on the judgment results of the two insulation diagnosis rules, induced current in the wire, external partial discharges, and noises will be eliminated by the analog differential measurement method. This design has advantages in on-line measurement.

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