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Author: search.filters.author.Jeenmuang, S.

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    The Application of Polarization and Depolarization Current on the Large Turbo-generators
    (2022-01-01)
    Jeenmuang, S.
    ;
    Pannil, P.
    ;
    Mongkolsatitpong, S.
    ;
    Trakuldit, S.
    ;
    Wuti, V.
    This paper represents the application of the polarization and depolarization current (PDC) measurement of the stator winding insulation of two large turbo-generators, which have the same rate of 50.8 MVA, and 11.5 kV. The PDC measurements were conducted on the stator winding insulation of both generators by using two different test circuits i.e., (individual) phase-to-ground insulation and interphase insulation circuits. Then, the PDC results of the two investigated generators were compared. To evaluate the phase-to-ground insulation condition of the stator winding insulation of both generators, the conventional dielectric parameters in the time domain, such as polarization index and insulation resistance, were also studied. Moreover, the PDC results in the time domain were converted into the dielectric dissipation factor in the frequency domain to allow the analyzing the phase-to-ground insulation of the stator winding of the generators. The PDC results of the phase-to-ground insulation circuits of both investigated generators illustrate the bent shape of PDC results which were affected by the influence of the stress control coating resulting in a high value of the Polarization index. Besides, the PDC results of the interphase insulation circuits of the first investigated generator illustrate the polarity reversal (or Anomalous current) of both PDC, while the second investigated generator illustrates the non-polarity reversal of both PDC. The polarity reversal of the PDC results of the interphase insulation was due to the dielectric loss of the interphase insulation is a lower influence when compared with that of phase-to-ground insulation.
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    Design of a Multi-channel PD Detector for Improving Common-mode Noise Reduction Performance in Measuring and Monitoring System
    (2022-01-01)
    Tongchim, N.
    ;
    Phansiri, N.
    ;
    Jeenmuang, S.
    ;
    Pattanadech, N.
    This paper deals with the design and implementation of a multi-channel partial discharge (PD) detector to improve noise reduction performance in the designed PD measuring and monitoring systems. Basically, the noise may be generated by the unexpected ground loop of the PD measuring system due to several coupling devices (CDs) being connected to the PD measuring instrument. In this paper, the signal-to-noise ratio (S/N ratio) was enhanced by using a bandpass filter and a programmable gain amplifier to filter the undesired noises and amplify the PD signal acquired in the CD. Besides, the category 7 cable (CAT7 cable) was utilized as a transmission line to transmit signals into the PD measuring instrument. This CAT7 cable with the grounded shield is comprised of 4 pairs of cables, i.e., the DC power supply cable, the PD signal cable, the test voltage signal cable, and the control signal cable used to connect between the coupling devices and the measuring instrument. Furthermore, at the input side of the measuring instrument, the Differential Receiver Amplifier was utilized to reduce the common-mode noise generated from the coupling device. Application of the proposed technique, the battery power supply, and the sophisticated isolation technique, e.g., fiber optic cable system of the active coupling device, are not needed. Furthermore, the designed PD detector was a simple and cheap price, including significant noise reduction.
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    The Effects of Coupling and Grounding on the Partial Discharge Pulse Propagation in the Underground Cable
    (2022-01-01)
    Rojanasunan, W.
    ;
    Chancharoensook, P.
    ;
    Jeenmuang, S.
    ;
    Mongkolsatitpong, S.
    ;
    Pattanadech, N.
    When a Partial Discharge (PD) pulse propagates through a cross-bonded (CB) power cable system, such pulse undergoes attenuation and dispersion along a cable. Moreover, the coupling effect occurs when a PD pulse propagates in HV cable joints and CB link lines. This paper aims to study the effects of coupling phenomena and groundings on the PD pulse propagation. The experiments were divided into 3 parts: the experiment for attenuation in the conductor and ground wire, the experiment for coupling effect, and the experiment for different grounding configuration. The experimental setups used a 30 m length of new 33 kV XLPE insulated cable. PD pulses was obtained from a PD calibrator, and the pulses are detected by Radio Frequency Current Transformer at various positions. The knowledge gained from this research should be useful for a deep understanding of pulse propagation and PD source localization in CB power cable systems.