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    A locating diagnosis of partial discharge on cross-bonding ground system
    (2021-05-19)
    Inwanna, W.
    ;
    Mongkolsatitpong, S.
    ;
    Chancharoensook, P.
    ;
    Pattanadech, N.
    At the present, Thailand has turned the attention to Underground Cable (UC) systems and trends to use it more to safety, stability and reliability of electrical system. However, one problem that can affect to this electrical system is the Partial Discharge (PD) problem. Most of PD problems are caused by incomplete installation, maintenance reason and insulation degradation on the weakest part, especially cable joint. This paper proposes a method of analysis to locate the PD source in UC systems with Cross Bonding (CB) focus on cable joints. This work has carried out in laboratory on CB system model using 50ohm R58 coaxial cable instead of underground cable. The PD detection technique according to IEEE 400.3 standard with a RFCT sensor to refer the appropriate signal. This work uses a PD diagnostic device that can filter noise from the PD groups and separate groups of PD for greater analysis accuracy. To determine which cable joint is PD source and to be able to fix it on the spot. The PD signal analysis are performed by using time of arrival method considered together with the characteristics and the polarity of the PD pulse.
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    Polarization and depolarization current measurement applied for investigation of underground cable system problems
    (2019-07-01)
    Pattanadech, N.
    ;
    Phongsirichairojna, T.
    ;
    Navapittayaratana, N.
    ;
    Nimsanong, P.
    ;
    Jirathipchaisakul, T.
    This research investigates the problems in XLPE cables system. The 12/20(24) kV underground cable with the cross section area of 240 mm<sup>2</sup> was used in the experiment. Two 3 meter long cables were connected by a cable joint where the defect was simulated on. The dielectric investigation of XLPE cable system by polarization and depolarization current (PDC) measurement was performed comparatively among four different cases: a healthy cable with healthy heat shrinkable joint (case1), a cable joint with an incision on XLPE surface (case2), a cable joint contaminated with 20 micron iron powder on XLPE surface (case3) and a cable joint contaminated with 20 micron copper powder on XLPE surface (case4). Diagnostic parameters, PDC shapes, dielectric dissipation factor (DDF) and conduction current, derived from PDC test results for analyzing the dielectric response are proposed in this paper.