由於地下電纜的故障難以定位，並且需要花費更多時間排除故障，因此提前預測故障並提前維護對於提升供電的穩定度有很大的幫助。目前已有很多研究透過局部放電的監測來預測絕緣故障，但是難以廣泛部署在地下電纜上。
本文主要開發一套能夠用於地下電纜的局部放電監測系統，其克服地下管道難以供電與通訊的限制。此系統由差動HFCT感測器，局部放電訊號處理電路、類比數位轉換器、Pi pico微控制器、LoRa無線通訊模組與資料儲存裝置組成，並且結合非接觸式電源，透過擷取電纜電流產生的磁場能量，作為監測系統的電力來源。
本系統能夠量測局部放電相位解析圖譜、計算特徵值並儲存資料，再藉由LoRa長距離傳輸、高接收靈敏度的特性，將訊號的特徵值直接傳輸到外界，不需要架設通訊線路。非接觸式電源透過超級電容儲存比流器產生的能量並供電給監測系統，只要在電纜上有電流的情況下就能運作，節省更換電池的維護成本，大幅降低部署的成本。

Because the faults of underground cables are difficult to location, and it takes more time to repair the faults, predicting faults and maintaining in advance are great help to improve the stability of power supply. At present, there are many studies have been carried out to predict insulation fault through partial discharge monitoring, but it is difficult to widely deploy on underground cable on.
This paper develops a partial discharge monitoring system that can be used for underground cables, which overcomes the limitation of the difficulty of power supply and communication in underground pipelines. It is composed of differential HFCT sensor, partial discharge signal process circuit, an analog to digital converter, a Pi pico microcontroller, a LoRa wireless communication module and a data storage system, and is combined with a non-contact power supply to capture magnetic energy generated by cable current as the power source for the monitoring system.
The system can measure the PRPD pattern of partial discharge, calculate the characteristic value and store the data, and then use the characteristics of LoRa long-distance transmission and high receiving sensitivity to directly transmit the characteristic value of the signal to the outside world without setting up communication lines. The non-contact power supply stores the energy generated by current transformer through supercapacitors and supplies power to the monitoring system. As long as there is current on the cable, it can operate, saving the maintenance cost of replacing the battery and greatly reduces the cost of deployment.

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