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Item type:Item, Dielectric response analysis for cable joint problems in medium voltage underground cable system(2020-01-01) ;Klienhom, Sitthisak ;Boonsaner, Nutthaphan ;Nimsanong, Phethai ;Chancharoensook, PhopKunakorn, AnantawatThis paper represents the investigation of dielectric response analysis of a cable system composed of a medium voltage XLPE underground cable, a heat-shrink cable joint and a heat-shrink cable termination. A 12/20(24) kV single core XLPE underground cable with the nominal cross-section area of 240 mm<sup>2</sup>, three pieces of 22 kV cable joints, and eight pieces of 22 kV cable termination were prepared for the experiment. Then, polarization and depolarization current (PDCs) measurement were performed. The experiments were divided into two parts. The first part was composed series of three tests, A — C, and the second part consisted series of two tests, D — E, as follows: Test A examined dielectric response of a 6 m healthy XLPE underground cable, Test B examined dielectric response of a 6 m healthy XLPE underground cable with two healthy cable terminations, Test C examined dielectric response of a two of 3 m healthy XLPE underground cable with healthy cable terminations connected by a healthy cable joint, Test D used the test object similarly as case C but the cable joint was contaminated with copper particles, and Test E used the test object similarly as case C but the cable joint was contaminated with tiny pieces of water blocking. From the experiment, the PDCs and the derived dielectric parameters such as geometrical capacitance, insulation resistance, polarization index, depolarization index, charge difference curve and charge ratio curve were analyzed. The PDCs and the derived parameters were found different for each case of study as details in this paper. Besides, the charge ratio proposed by authors is a valuable parameter for the diagnosis of insulation system of high voltage equipment. - Some of the metrics are blocked by yourconsent settings
Item type:Item, Polarization and Depolarization Current Measurement for Foreign Object Detection in Gas-Insulated Transmission Line(2019-10-01) ;Nganpitak, Tritod ;Chancharoensook, PhopPattanadech, NorasagePolarization and depolarization current (PDC) test is one of non-destructive insulation test method that usually uses for diagnosis the solid and liquid insulation problems. In case of gas-insulated transmission line (GIL), it not only comprises of gas insulation but also the solid insulation such as cone insulators. This paper presents the PDC measurement for foreign object detection in GIL. A 230kV, 2500A, single phase GIL with 2 m length was used in the PDC experiments. The external diameter of this GIL conductor and enclosure are 92 and 366 mm respectively. In the experiment, defects on the cone insulator was simulated in three cases, i.e. 1) cone insulator was attached with a paper tape, 2) cone insulator was attached with an aluminum foil, 3) cone insulator was attached with a moist paper. The width of the simulation defect was approximately 2 mm. The lengths of the simulation defects were varied from 25 - 200 mm depending on defect types. PDC test results obtained from the GIL with the simulated defect cone insulators were compared with that of clean and dry cone insulator as reference. The results of the experiments showed that PDC curves obtained from GIL with the simulated defect cone insulators were clearly different from that of the reference case. Other analyses are reported in the paper.
