Pannil, Pittaya

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Pannil, Pittaya
Alternative Name
Pannil, P.
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Email
pittaya.pa@kmitl.ac.th

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    Experience in Partial Discharge Investigation of a 155 MVA Air-Cooled Generator
    (2024-01-01)
    Pathanrat, Khomsan
    ;
    Chumpiboon, Komin
    ;
    Jeenmuang, Siwakorn
    ;
    Worthong, Tehneht
    ;
    Pannil, Pittaya
    This paper presents the Partial Discharge (PD) and Polarization and Depolarization Current (PDC) investigation for a 155 MVA air-cooled generator. The visual inspection of the stator winding insulation was carried out during the annual preventive maintenance. Several defects in the area of the end winding stator were evidenced. Thereafter, the refurbishment of these problems was performed to improve the stator winding insulation condition, and the offline PD & PDC test was conducted accordingly. Besides, the online PD was continuously monitored, through capacitive PD sensors which have been installed on the terminal of the generator two units per phase. The operating conditions during online PD measurement were also recorded. In this paper, the results from both offline and online PD measurements were presented.
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    The Experiment of Partial Discharge for Cast Resin Transformer
    (2024-01-01)
    Aiamrungruang, Phitthaya
    ;
    Pannil, Pittaya
    ;
    Dorkmai, Kritsada
    ;
    Maneerot, Sakda
    ;
    Jeenmuang, Siwakorn
    Dry-type cast resin transformers, utilizing epoxy resin insulation instead of traditional liquid insulation like mineral oil, are designed to prioritize safety, avoid fire hazards, be environmentally compatible, and endure short circuits well. Limitations of dry-type transformers are the installation area by which it should be dry, free from dust, excessive moisture, fertilizers, chemicals, and other corrosive fumes or fumes. This paper investigates the Partial Discharge (PD) phenomena occurring on a 12 kV dry-type transformer surface using HighFrequency Current Transformers (HFCT) with 100 kHz -20 MHz bandwidth as a PD detection device. The simulated PD sources were made from the conductive wire. Moreover, the scheme of winding connections in the dry-type transformer related to cross-talk phenomena between transformer coils is also reported. The recorded Phase-resolved PD (PRPD) and the PD Inception Voltage (PDIV) have been summarized and compared, as described in this paper.
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    Partial Discharge Investigation of 22kV Distribution Transformer
    (2024-01-01)
    Dechothamsathit, Vorawut
    ;
    Pannil, Pittaya
    ;
    Yamsiri, Thummanoon
    ;
    Chumpiboon, Komin
    ;
    Jeenmuang, Siwakorn
    This paper presents an off-line partial discharge (PD) experiment conducted on a 22 kV/400 V distribution transformer, which was decommissioned after 20 years of service. The study investigates the impact of reduced oil levels within the transformer on PD characteristics that are expected to facilitate PD activity within the transformer. The experiments were performed with reduced oil levels below the top clamp and using both single-phase and three-phase voltage excitations, with PD measurements recorded for each case. The PD signals were measured using High-Frequency Current Transformers (HFCTs) and capturing current pulses of PD in the frequency range of 100 kHz to 20 MHz. Additionally, transformer oil tests were performed, including moisture content, oil breakdown voltage, and oil conductivity. The results of the PD measurements and oil tests are introduced and discussed in this paper.
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    Experiment of Dielectric Frequency Response for Aged ZnO Surge Arrester
    (2025-01-01)
    Aiamrungruang, Phitthaya
    ;
    Methavithit, Winai
    ;
    Pannil, Pittaya
    ;
    Chuayin, Chaitawat
    ;
    Zinck, Matthieu
    Condition-based monitoring of surge arresters has gained increasing attention in modern power system asset management, especially for medium-voltage equipment. This paper presents an investigation into the dielectric frequency response (DFR) analysis technique as a diagnostic method to evaluate aging and unhealthy conditions in 21-kV metal oxide surge arresters (MOSA). Four types of simulated defects, excessive number of lightning current stress, cracking, moisture ingress, and tracking, were introduced to represent common field failures. The DFR technique enables frequencydomain interpretation of dielectric properties, providing insight into insulation behavior over a wide frequency range. The test results show a significant variation in capacitance and dissipation factor corresponding to different defect types. Among these, moisture ingress exhibited the most severe deterioration. The findings suggest that DFR is a viable offline diagnostic method that can support preventive maintenance strategies for high-voltage surge arresters.
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    The Experiment of Dielectric Frequency Response of Serviced Aged Distribution Transformer
    (2024-01-01)
    Posrimahapoch, Purichaya
    ;
    Maneerat, Noppadol
    ;
    Daengdee, Danaiwat
    ;
    Jeenmuang, Siwakorn
    ;
    Pannil, Pittaya
    Outdoor Distribution Transformers typically encounter random environments and affect moisture in any ingress ways, e.g., defective breathing, oil leakage, or human error during internal inspection, etc. Such moisture is a very important enemy of the insulation integrity of the transformer. It may cause the failure of the transformer eventually. Therefore, the condition of the transformer insulation needs to be monitored. Dielectric Frequency Response (DFR), also known as Frequency Domain Spectroscopy (FDS), and Polarization and Depolarization Current (PDC) are nondestructive tests providing efficient diagnostic for transformer insulation. The test results can be used to estimate moisture content and oil conductivity. In this paper, the dielectric investigation of a 315 kVA, 22 kV serviced aged distribution transformers, which have been retired for 6 months after being utilized for more than 20 years, was conducted. The experiment results of the DFR and the PDC tests including the investigated mineral oil characteristics (i.e., oil breakdown voltage, moisture content, and tan delta) are reported and analyzed. They should be useful to understand the condition of the transformers.