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    Dielectric Response Analysis on Artificial ZnO Surge Arrester Degradation Using Polarization and Depolarization Current Based Method
    (2024-01-01)
    Chuayin, Chaitawat
    ;
    Pattanadech, Norasage
    ;
    Zinck, Matthieu
    ;
    Methavithit, Winai
    ;
    Suksagoolpanya, Suthat
    This paper presents an alternative method to investigate the problems of surge arrester based on dielectric response analysis. The study is made using a 21-kV, 25-kA station class surge arrester to be test specimens, the former Zinc Oxide (ZnO) varistors inside were removed and replaced with artificial degraded ZnO varistors (impulse ageing, tracking problems, moisture ageing under wet and dry condition and cracking ZnO varistors). The experiments are carried out by Polarization and Depolarization Current (PDC) measurement. The test result analyses were proposed in terms of both the time domain and frequency domain. The measurement results show significant differences in dielectric response characteristics between healthy surge arresters and aged surge arresters. In addition, the dielectric response analysis tends to characterise the problems of surge arrester i.e., conduction problems and polarization problems which will be further discussed in this paper.
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    The Time Domain Dielectric Response of 138 kV and 550 kV OIP Bushing
    (2024-01-01)
    Yamsiri, Thummanoon
    ;
    Bunlaksananusorn, Chanin
    ;
    Suksawat, Dusit
    ;
    Rojanasunan, Warisanan
    ;
    Jeenmuang, Siwakorn
    In this paper the dielectric response in time domain which is polarization and depolarization current (PDC) measurement is applied to assess the global condition of OIP bushings. The bushings in this paper are five 138 kV OIP bushings and three 550 kV OIP bushings which are out of service already. From the PDC results, capacitance and current trends of both voltage levels were investigated individually. PDC results in this paper can be useful data for further analysis and diagnostic.
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    Application of Dielectric Spectroscopy Analysis to Identify Unhealthy Surge Arrester by Using PDC Measurement Technique
    (2024-01-01)
    Chuayin, Chaitawat
    ;
    Pattanadech, Norasage
    ;
    Zinck, Matthieu
    ;
    Suksagoolpanya, Suthat
    ;
    Methavithit, Winai
    At present, power grid asset management is becoming a topic of greater interest, as is the condition-based diagnosis of surge arresters to ensure power supply reliability on medium and high voltage networks. Extensive studies on failure mode and arrester forensics have been conducted and are continuing, investigating with various techniques, to predict and investigate their failures. This paper presents the investigation of dielectric spectroscopy of 21-kV MV surge arresters to identify unhealthy problems using Polarization and Depolarization current (known as PDC) measurement techniques, four artificial problems (which consist of lightning, cracking, moisture ingressive, and tracking problems) were simulated on surge arresters. With the PDC measurement, it is allowed to be interpreted in both the time domain and frequency domain. The dielectric parameters will be further presented and compared. The significant relationship of dielectric response characteristics is validated by test results and is highlighted in detail in this paper. Finally, an alternative invasive offline measurement technique is proposed for surge arrester failure detection.
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    Analysis of electrical insulation paper by Simulation for analyze Polarization and Depolarization current testing method
    (2023-01-01)
    Rakkaphan, Chananut
    ;
    Boonsaner, Nutthaphan
    ;
    Pattanadech, Norasage
    ;
    Chancharoensook, Phop
    This paper presents the quality analysis of insulation paper in distribution transformer oil in Thailand. The country locates in tropical zone and therefore experiences relatively high temperature. Analytical principles based on polarization and depolarization current method with various test conditions are used. Computer simulation can help to analyze the efficiency of insulation paper in transformer oil under different voltages and temperatures. The tested system consists of an electrode inside a high-Temperature and high-voltage control cabinet. It can be concluded that increasing temperature has a marginal effect on the electric field stress of the electrode. However, the rising temperature significantly affects the polarization current that flows through the insulators. The results can indicate the limitation of using oil insulation paper and how to improve the quality of it.
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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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    Polarization and Depolarization Current Characteristics of Thermally Stressed Stator Coils
    (2020-10-25)
    Thungsook, Kittisak
    ;
    Phumipunepon, Natnaree
    ;
    Worthong, Tehneht
    ;
    Methavithit, Winai
    ;
    Vittayakorn, Wanwilai
    When the motor is exposed to thermal stress more than its limit, its insulation characteristic degrades and/or deteriorate. This paper presents the characteristic of stator coils under thermal stress by analyzing the polarization and depolarization current (PDC) characteristics. This research used a slot part of stator coils, which were obtained from a synchronous motor rated 6.6 kV with class F (155°C) insulation. Twelve test samples of motor stator coils were divided into four groups depending on the stress temperature levels, 100°C, 140°C, 180°C, and 220°C. Each specimen was heated at the specified temperature for four cycles (6 hours per cycle). To analyze the insulation characteristic of the tested specimen, PDC measurement was performed. It was found that the PDC magnitude decreased related to the number of thermal cycles and temperature levels, as described in this paper.
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    Polarization and Depolarization Current Characteristics of Natural Ester Impregnated Pressboards with Different Periods of Impregnation
    (2020-10-25)
    Maneerot, Sakda
    ;
    Siriworachanyadee, Jompatara
    ;
    Likhitsupin, Wit
    ;
    Likhitsupin, Suwapich
    ;
    Srinangyam, Chissanupong
    This paper represents the polarization and depolarization current (PDC) characteristics of natural ester impregnated pressboards with different impregnation period. The pressboard specimen were prepared as a rectangular shape (the length and the width are 120 mm as well) and thickness dimension of the pressboard in the experiment was approximately 1.6 mm. The pressboards were dried up in the vacuum oven with temperature at 80°C for 12 hours under 200 mbar pressure. In addition, these pressboards were divided into 3 groups according to the impregnation periods. The 1st group, the pressboard was non-impregnated with natural ester. The 2nd and 3rd group, the pressboards were impregnated at 60°C for 8 and 16 hours, respectively, under 200 mbar pressure-controlled condition. The plane-plane electrodes inserted with the specified number of the pressboard specimens were prepared. These electrodes were installed in the test cell filled with the natural ester. A 24 kV AC Voltage was applied to the test cell for 3 months. At the end of the first month, half of the pressboard samples was token from the test cells. Then, the PDC characteristics of these natural ester impregnated pressboards were investigated. At the end of the third month, another half of the pressboard samples was token from the test cells to perform PDC measurement also. It was found that the PDC values of the pressboards with longer period impregnation process were lower than these of the pressboards with longer period impregnation process. Besides, the PDC values of the pressboards experienced with longer electric field stress period (3 months) were higher than these of the pressboards experienced with shorter electric field stress period (1 month).
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    Experience with Polarization and Depolarization Current Measurements on Contaminated Motor
    (2020-10-25)
    Phumipunepon, Natnaree
    ;
    Pattanadech, Norasage
    Motors and generators are often installed in a location where makes them susceptible to contamination. For a long period of contaminant concentration, such contaminant can lead to motor failure. This paper presents the insulation characteristic of contaminated motor by comparing polarization and depolarization current (PDC) characteristics of the contaminated motor before and after performing overhaul maintenance. In the experiment, there are two 6.6 kV motors in which the insulation conditions of the motors before overhaul are contaminated with dust, bearing oil, and moisture. The test result indicates that the high-pressure water cleaning and drying applied for contaminated motor can only reduce the contaminants and moisture not change bulk insulation characteristics.
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    Test Chamber Designed with Temperature Control for Partial Discharge and Polarization and Depolarization Current Testing
    (2020-10-25)
    Boonsaner, Nutthaphan
    ;
    Panoon, Nitouch
    ;
    Chancharoensook, Phop
    ;
    Pattanadech, Norasage
    This paper presents the temperature-controlled test chamber for Partial Discharge and Polarization and Depolarization Current test of dielectric liquid including impregnated pressboards with the various conditions. Besides, the temperature of the test specimen is controlled between room temperature to 300°C. The temperature distribution in the test chamber was simulated. Besides, the electric field stress at the electrodes were simulated. Furthermore, different kinds of sensors such as a thermocouple, gas sensors, and so on were designed to be equipped within the test chamber. From the simulated result, both electric field stress and temperature distribution were in the given conditions.
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    The Effect of Electrical and Moisture Degradation of Metal Oxide Varistor with Insulation Diagnosis
    (2020-10-25)
    Chuayin, Chaitawat
    ;
    Zinck, Matthieu
    ;
    Kunakorn, Anantawat
    ;
    Pattanadech, Norasage
    Condition based monitoring of surge arresters (SA) has become a primary concern to ensure power supply quality on medium and high voltage networks. Understanding of SA behavior helps forecast their failure. This paper presents the analysis of dielectric response and conductivity of Metal Oxide Varistor (MOV) under degradation factors (normal ageing, impulse ageing and moisture ageing) using Polarization and Depolarization techniques. Normal ageing is represented by stressing the MOV with 115°C temperature. For impulse ageing, 20, 40 ,60 and 100 shots of positive and negative polarity of standard lightning impulses current were applied. Moisture ageing was performed by soaking MOV under 115°C temperature for 12 hours representing wet condition and the soaked blocks were left at room temperature for 24 hours representing dry condition. Polarization and Depolarization Current (PDC) was measured after each ageing step. Resistivity, conductivity and polarization index were interpreted for insulation diagnosis. The experiments were taken on the MOV with rated voltage 3 kV and 5kA-nominal discharge. The importance of nondestructive electrical diagnostics based on polarization methods is validated by test results and is highlighted in detail in this paper. Finally, the results of different ageing factors were compared and discussed.