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Author: search.filters.author.Pattanadech, N.Subject: search.filters.subject.partial discharge

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    Insulation Diagnosis of Distribution Class Metal Oxide Surge Arrester Using Polarization and Depolarization Techniques
    (2022-01-01)
    Turatham, S.
    ;
    Pannil, P.
    ;
    Maneeroj, S.
    ;
    Methavithit, W.
    ;
    Zinck, M.
    Imperfection of metal oxide surge arrester (MOSA) becomes a factor that affects the power supply quality on medium and high voltage networks. Understanding the coordination of MOSA insulation systems helps describe their failure. This paper presents the analysis of the dielectric response of imperfect MOSA from the factory using polarization and depolarization techniques. The experiments were taken on 21 kV and 24 kV MOSA samples which were validated by testing topics, i.e., the reference voltage, voltage-current characteristic curves, and partial discharge (PD). Polarization and Depolarization Current (PDC) was measured after 21 kV MOSA samples had taken PD testing and 24 kV MOSA samples had taken reference voltage testing. Resistivity, capacitance, and polarization index were interpreted for insulation diagnosis. The importance of non-destructive electrical diagnostics based on polarization methods is validated by PDC test results and is highlighted in detail in this paper. Finally, the results of different PDC were compared and discussed.
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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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    Partial discharge inception voltage investigation of mineral oil: Effect of electrode configurations and oil conditions
    (2016-10-01)
    Pattanadech, N.
    ;
    Muhr, M.
    The aim of this paper is to describe the Partial Discharge Inception Voltage (PDIV) and Partial Discharge (PD) characteristic of mineral oil tested by various electrode configurations. Furthermore, mineral oil with different conditions was investigated under AC voltage. The PDIV and PD of the mineral oil, Nynas Nytro 4000x, with water content about 4 ppm was investigated by using various electrode configurations of needle - plane and needle - sphere electrodes under room temperature. The PDIV test circuit was set up according to IEC 60270. Then, two PDIV measurements were applied for the investigation. The first PDIV test procedure (IEC method) was performed in accordance with IEC 61294. The second PDIV test procedure so-called combined PDIV method was adapted from IEC standard. Moreover, the electric field distributions of the electrode systems were also calculated. According to the test results, PDIV depended clearly on the electric field stress of the electrode system and the test method. Compared with other electrode configurations, the 10 μm tip radius needle - 75 mm dia. plane electrode gave the highest electric field stress and inversely provided the lowest PDIV value tested by both test methods. The combined PDIV test method generated the PDIV, charge quantity, and charge repetition significantly lower than measuring by IEC method. To investigate the effect of oil conditions on PDIV and PD characteristics, the combined conditions of temperature and water content of the mineral oil were controlled as the parameters for investigation. It was found that the water content in the mineral oil influenced approximately on PDIV value when the oil temperature was at room temperature. However, at the oil temperature of 40-90 °C, the PDIV values of the mineral oil with water content 4, 20 and 40 ppm were relatively the same. From the PD pulse current test results, PD pulse current recorded at the PDIV value from both test methods was about 0.15-1.3 mA. Pulse duration was in the range of 0.7-9 μs and the rise time was between 40-570 ns.