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Author: search.filters.author.Nganpitak, Tritod

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    Dielectric Loss Factor Measurement in A Gas-Insulated Transmission Line by Using Very Low Frequency Test
    (2020-06-01)
    Nganpitak, Tritod
    ;
    Rugthaicharoencheep, Nattachote
    ;
    Chancharoensook, Phop
    ;
    Pattanadech, Norasage
    Very low frequency tan delta measurement (VLF-TD measurement) is one of the insulation diagnosis methods usually uses to diagnosis the condition of electrical cable insulation. However, this research focuses on using VLF-TD measurement with a gas-insulated transmission line (GIL). The 230kV, 2500A, single phase, GIL with 2.0 m length was installed and prepared for experiments. in this paper, VLF-TD experiments were divided into 5 cases, classified by using types of artificial defects as a criterion, i.e. 1) The clean GIL without any defect, 2) The GIL with scratched on the surface of cone insulator, 3) The GIL with tracking path on the surface of cone insulator, 4) The GIL with protrusion on high voltage conductor and 5) The GIL with protrusion on enclosure. The average tan delta, VLF tan delta stability, and VLF differential tan delta were presented and compared in this paper.
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    Experiences in nonconventional partial discharge measurement for gas-insulated substation in Thailand
    (2020-01-01)
    Nganpitak, Tritod
    ;
    Kunakorn, Anantawat
    ;
    Klienhom, Sitthisak
    ;
    Likhitsupin, Suwapich
    ;
    Jariyawichai, Parinya
    Nowadays, nonconventional partial discharge (PD) measurement has become essential for diagnosis the high-voltage insulation condition. The nonconventional PD measurement not only uses for periodic assessment but also uses for commissioning test after transportation and installation. This paper focuses on nonconventional PD test techniques using Ultra-high frequency (UHF) sensors, acoustic sensors and light detection sensors for gas-insulated substation (GIS) commissioning test. Fundamental defects found in GIS: (1) Hopping particles (2) Fixed protrusions (3) Floating potential and (4) Voids are described. Then, explanation about how to detect such defects by using UHF, acoustic and optical methods. Afterwards, PD commissioning tests were performed with three 230 kV electricity generating authority Thailand (EGAT) GISs, i.e., Phayao EGAT GIS, Lamphun 2 EGAT GIS and North Bangkok EGAT GIS. The PD signals due to hopping particle were found by using UHF sensors at Phayao and North Bangkok EGAT GISs. The acoustic PD test technique was used in Phayao EGAT GIS to locate such particles. In case of Lamphun 2 EGAT GIS, by using UHF measurement, PD signals were found due to tracking caused by flashover on the cone insulation surface. Later, light detection sensors were used to detect the PD location. As a result of studies, its clearly guarantee the powerful accuracy and efficiency of nonconventional PD measurement by the combination of UHF and acoustic technique including light detection sensors.
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    Polarization and Depolarization Current Measurement for Foreign Object Detection in Gas-Insulated Transmission Line
    (2019-10-01)
    Nganpitak, Tritod
    ;
    Chancharoensook, Phop
    ;
    Pattanadech, Norasage
    Polarization 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.
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    The study of conventional partial discharge measurement for gas insulated line
    (2019-07-01)
    Pattanadech, Norasage
    ;
    Houngtaisong, Chakkri
    ;
    Wichakul, Chalantorn
    ;
    Thanormsakdomrong, Narinnitiporn
    ;
    Monklang, Natthanon
    Partial discharge (PD) measurement is one of the insulation diagnosis tools used for diagnosis the condition of the high voltage apparatus. Generally, PD is generated at the highly electric field stress site in the insulation system. This research focuses on PD measurement in a gas-insulated line (GIL) by using the conventional PD measurement. The 230kV, 2500A, single phase, GIL with 2.5m length was setup and used for experiments. In this paper, the experiments were divided into 4 cases, according to the types of artificial protrusions, i.e. 1) a protrusion on the high voltage conductor 2) a protrusion on the enclosure and 3) two protrusions on both conductor and enclosure. 4) a protrusion on the conductor covered by insulation compartment. The lengths of protrusions were varied. The results of experiment were presented with the phase resolved partial discharge patterns.
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    Dielectric Response Analysis of Mineral Oil Immersed Transformer Insulation during Manufacturing Process
    (2019-06-01)
    Nganpitak, Tritod
    ;
    Nimsanong, Phethai
    ;
    Maneerot, Sakda
    ;
    Pattanadech, Norasage
    Polarization and Depolarization current (PDC) method is one of non-destructive insulation testing methods that can be used for diagnosis the insulation conditions of high voltage equipment. This paper presents the PDC analysis of an oil immersed distribution transformer measured during the manufacturing process. A 22 kV, 30 kVA single phase transformer was designed and constructed. During manufacturing process, the polarization current and depolarization current of the transformer insulation were measured for 6 case studies as follows: 1) paper insulation between iron core and low voltage (LV) windings before dry and vacuum in the oven, 2) paper insulation between LV and high voltage (HV) windings before dry and vacuum in the oven, 3) paper insulation between iron core and LV windings after dry and vacuum in the oven, 4) paper insulation between LV and HV windings after dry and vacuum in the oven, 5) oilpaper insulation between iron core and LV windings after dry and impregnation process and 6) oil-paper insulation between LV and HV windings after dry and impregnation process. Then, PDC test results were analyzed. It was found that the moisture content in the paper insulation clearly affected the capacitance at power frequency, and PDC shapes. Besides, the impregnation process had a good effect on the capacitance ratio and dielectric dissipation factor. Moreover, the current difference of dry paper insulation between HV and LV windings presented the nonlinear characteristic both before and after impregnation process.