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The Experiment of Partial Discharge testing for Low Voltage Motor
(2025-01-01)
Sawangsri, Jaturaphat
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Wiangtong, Theerayod
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Pathanrat, Khomsan
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Ruangwong, Khomsan
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Jeenmuang, Siwakorn
Low-voltage (LV) motors are widely used and highly popular in industrial settings due to their critical role in production processes. Any malfunction or failure of an LV motor can lead to production downtime, resulting in reduced output and potential revenue loss. Therefore, it is essential to conduct diagnostic assessments that evaluate the reliability of the insulation system in LV motors. Partial Discharge (PD) testing is recognized as a highly effective and reliable method for assessing the condition of motor insulation. This paper presents PD testing on LV motors to investigate the behavior of partial discharges using multiple analysis techniques. Additionally, an acoustic camera is integrated into the testing process to accurately identify the discharge locations.
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Partial Discharge Detection beyond the Frequency Ranges of IEC 60270
(2024-01-01)
Rajakrom, Asawin
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Cheechang, Chayapitch
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Laochu, Prechapol
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Nimsanong, Phethai
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Yutthagowiht, Peerawut
Due to the high background noise encountered during on-site partial discharge (PD) detection of power cables, calibrating PD detection systems at low PD levels becomes challenging, resulting in low sensitivity of PD detection systems. Achieving a 1-nC PD charge within the frequency range recommended by IEC 60270, which is lower than 1 MHz, is often difficult in practice. This paper presents an analysis of PD pulse currents in the frequency domain and proposes an alternative approach for PD detection during on-site testing of power cables. In the proposed method, the center frequency for PD detection is shifted to frequencies exceeding one megahertz, which lies outside the recommended frequency ranges of IEC 60270. Typically, the center frequency falls within the range of 1.5 MHz to 2.5 MHz, with a frequency bandwidth of several hundred kilohertz. By utilizing such frequency ranges, the signal-to-noise ratio of the PD pulse current significantly increases compared to the standard approach. Despite falling outside the standard-recommended frequency ranges, this adjustment allows for calibration using a 50-pC PD charge.
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Partial Discharge and Dissolved Gas Analysis on 22kV MV Oil-type Transformer - Case Study
(2024-01-01)
Inwanna, Woranan
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Waiwicha, Supisara
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Vanijkirati, Parada
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Monkolsatitpong, Suriya
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Chumpiboon, Komin
Detecting faults leading to potential failure of important power distributing transformers in the power system before an occurrence is an important attribute. Various inspection methods are available, however online PD and oil analysis remain the most preferred method. The methods mentioned do not require equipment shutdown. This paper introduces a case study of the 22kV transformer with online PD and DGA results indicating signs of problems in the insulation. The PD group found initially had an increase in density of signals during the three months and the magnitude shows an upward trend. DGA results found H2 and CH4 gas, the latter is a key gas indicating PD. Results show an increasing trend of almost three times as high during the latter half of the year. In addition, CO, CO2, and C2H6 gases were also found to be higher than average. Virtual inspection was conducted after the transformer was shut down. The surface is found to be uneven around the bus bar, causing high temperatures in the transformer which then impacts the insulation performance.
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The Experiment of Partial Discharge for Cast Resin Transformer
(2024-01-01)
Aiamrungruang, Phitthaya
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Pannil, Pittaya
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Dorkmai, Kritsada
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Maneerot, Sakda
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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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Off-line and On-line Automatic and Unsupervised Partial Discharge Diagnostics of Electrical Asset Components
(2024-01-01)
Pattanadech, Norasage
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Jeenmuang, Siwakorn
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Udomluksananon, Patt
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Chumpiboon, Komin
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Shafiq, Muhammad
This paper deals with applications of an innovative approach to on-line and off-line partial discharge (PD)-based condition maintenance, where PD detection and analytics are fully automatic and do not require the support of PD experts. PD was measured off-line on a 50 kV A, 22/0.4 kV distribution transformer and on 115 and 230 kV transformer bushings, showing in both cases that PD can be detected and analyzed automatically according to the SID (Separation, Recognition, Identification) procedure. On-line measurements performed on MV generators are also reported and discussed, highlighting that there is potential for on-line MV (and HV) monitoring with automatic and unsupervised noise rejection, and identification of PD phenomena that can feed health assessment software to reach optimized maintenance plans.
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Characterization of Electromagnetic Wave in Transformer for Partial Discharge Detection
(2023-01-01)
Suwan, Supakorn
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Tiengthong, Thanadol
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Southisombath, Phouthong
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Promwong, Sathaporn
The increasing demand for electricity and the potential risks associated with partial discharge highlights the critical importance of robust transformer condition monitoring. Electromagnetic methods offer a promising approach to monitoring transformer health, benefiting from their ability to minimize external interference and their broad operating bandwidth covering HF, VHF, and UHF frequencies. The IEC 62478 standard provides multiple methodologies to leverage electromagnetic techniques in transformer health assessment, encompassing the analysis of electromagnetic waves through directivity, sensitivity, and transmission properties. In this study, we specifically investigate the transformer's UHF transmission characteristics. A vector network analyzer measures and records both transmitting and receiving elements of the UHF transmission channel and the UHF antenna. The measurements within the transformer tank simulate the realistic transformer environment. An optimum receiver is implemented at the receiver end to optimize the received signal quality. The results are comprehensively evaluated by analyzing the UHF transmission channel's path loss and transmission gain within the transformer. The primary objective of this research is to thoroughly examine the UHF transmission characteristics for efficient transformer condition monitoring, offering valuable insights for researchers and engineers involved in mitigating the risks associated with partial discharge in transformers.
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Partial Discharge Testing on MV Motor - Case Study
(2023-01-01)
Jeenmuang, Siwakorn
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Rojanasunan, Warisanan
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Dorkmai, Kritsada
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Chumpiboon, Komin
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Udomluksananon, Patt
A failure of a medium voltage (MV) motor during its operation could force an outage of the power plant and also lead to a loss of cost. Hence, the method to ensure the insulation quality of such a motor is needed. Partial discharge (PD) testing is one of the effective methods used to determine the defect and evaluate the integrity of the machine insulation. This paper presents the application of off-line PD testing on MV motors. In the experiment, the PD test instrument conforming to standard IEC 60270 was used as a charge-based measurement. Moreover, during the PD testing, an acoustic imaging camera was employed as an alternative technique for locating the PD sources in the stator winding part. Once PD takes place, it can generate the pressure acoustic wave that propagates surrounding the PD source. Thus, the PD source in the area of endwinding can be located by this technique. From the charge-based PD test results, the phase-resolved PD (PRPD) pattern was considered to identify the type of PD source. It was found that almost MV motors tested have delamination in the bulk insulation. In some cases, the PRPD pattern exhibits the discharge in the area of the overlap region between the semiconductive and stress grading coating in the slot exit, which confirms by using the acoustic technique.
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The Study of Partial Discharge Test on Service-Aged Cable Termination
(2023-01-01)
Laohapongpan, Trinai
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Wiangtong, Theerayod
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Kerdmanee, Sittipong
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Lacharochana, Sakda
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Jeenmuang, Siwakorn
This paper presents the partial discharge (PD) testing on the plug-in gas-insulated switchgear cable termination taken out of service. The shield electrodes were designed to geometrically electric field control in the area of the insulation screen edge of the cable part. The PD test of the cable termination was performed. In addition, a computed radiography technique with X-ray was also performed to evaluate the mechanical integrity of the supporting spring of the cable termination. The fatigue of the supporting spring was evidenced. Moreover, the cable termination was disassembled and re-assembled to perform the PD test again. The PD characteristics, including PD magnitude, PD inception voltage (PDIV), and phase-resolved PD (PRPD) patterns, were reported. The PD test results revealed that the PDIV was lower than the operating voltage. Besides, the PRPD patterns exhibited internal discharge inside the cable termination. From the PD test results and computed radiographic, it was assumed that they might be caused by discharge in the interface between the stress cone and epoxy insulator.
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Characterization of Electromagnetic Wave Propagation in Transformer for PD Detection Analysis
(2022-01-01)
Tiengthong, Thanadol
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Jaya Marindra, Adi Mahmud
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Pattanadech, Norasage
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Promwong, Sathaporn
The characterization of transformer wall effects a big problem regarding to the partial discharge, which caused substantial business losses and partial discharge analysis. Previously, there were methods of examination and evaluation using ultrasonic and acoustic waves, for this thesis saw the importance of having studied and done. Test the transmission of electromagnetic waves in a power transformer. The vector network analyzer was used to measure and record the results. A microstrip patch antenna was used to evaluate the experimental measurements on the designed transformer wall at different locations. The results obtained from the experiments will be analyzed, evaluated, and compared to the transfer function of the electromagnetic wave in the transformer. Considering the transfer function, power delay profile, and path loss, in the cases of no obstruction and obstruction from the evaluation and comparative consideration. Studies and experiments show that the data obtained measuring electromagnetic wave characteristics in transformers are guidelines in the study and analysis of partial discharges in the transformer. And primary data for the future analysis of partial discharges in the transformer.
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Insulation Diagnosis of Distribution Class Metal Oxide Surge Arrester Using Polarization and Depolarization Techniques
(2022-01-01)
Turatham, S.
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Pannil, P.
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Maneeroj, S.
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Methavithit, W.
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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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