• Title, Summary, Keyword: Dissipation factor

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Development and Its Characteristics of a Dissipation Factor Standard (손실계수 표준기 제작 및 그 특성)

  • Kim, Han-Jun;Kang, Jeon-Hong;Han, Sang-Ok
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.527-528
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    • 2006
  • A dissipation factor standard of decade type having the range of 1 to 0.0001 at the frequency of 1 kHz and 10 kHz was fabricated using "T" networks combined R and C components. The values of the fabricated dissipation factor standard were adjusted within 1% of the nominal values at 0.0001 dial range and 0.05% at the others. This dissipation factor standard is used as a working standard for calibration of a impedance measurement meter at KRISS and as a primary standard of dissipation factor field at NML-SIRIM in Malaysia.

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Study on Diagnosis for Transformers by Tan $\delta$ and Moisture of Insulation Oil According to Thermal Aging (절연유의 열열화에 따른 Tan $\delta$와 수분의 변화에 의한 변압기의 예방진단 연구)

  • HwangBo, Seung;Han, Min-Koo;Kwak, Hee-Ro;Kim, Jae-Chul
    • Proceedings of the KIEE Conference
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    • pp.241-245
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    • 1988
  • This paper reports the experiments regarding to diagnosis techniques for power transformers by measuring dissipation factor and moisture contents of mineral oils. Thermal aging environments of mineral oils were varied by the specially designed systems. Thermal aging of elevated temperature of $90^{\circ}C$ was performed for about 240 and 460 hours, respectively. Dissipation factor, permittivity, and water content were measured. Our test samples were not exposed to air. Dissipation factor increased while permittivity did not change. The level of dissipation factor determining the insulating quality of mineral oil was compared with the previous results of resistivity and several correction factor.

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A study on the heat cycle aging of insulation materials in large generator stator windings (대형발전기 고정자권선 절연재료의 열 사이클에 의한 열화에 관한 연구)

  • 김희곤;박영관
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.45 no.4
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    • pp.553-557
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    • 1996
  • Heat cycle aging of insulating materials in large generator stator winding has been investigated using both on-line and off-line test methods. On this study, principally, off-line test against actual generator in service was carried out to acquire information about polarization index(PI) and dissipation factor, dissipation factor tip-up, maximum partial discharge for the purpose of remnant breakdown voltage and life assessment. It was found from the tests that both dissipation factor and maximum partial discharge decreased with the increase of operating hours and starting numbers. It was found from off-line tests that the remnant breakdown voltage had a strong relationship with both dissipation factor and maximum partial discharge the remnant breakdown voltage as a results of both operating hours and starting number and the nondestructive tests were proposed as parameters which can predict the remnant lifetime of insulating materials in large generator stator windings. (author). 8 refs., 8 figs., 2 tabs.

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Measurement of the Degree of Cure of Thermosetting Resin Matrix Composite Materials (열경화성수지 복합재료의 경화정도의 측정에 관한 연구)

  • 김진수;이대길
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.9
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    • pp.2154-2164
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    • 1995
  • In this study, a dielectric cure monitoring system which consists of an electric circuit, a sensor and a personal computer was developed to on-line monitor the dielectric properties of carbon fiber epoxy composite materials. Also, the kinetic model of carbon fiber epoxy composite materials was developed by curve fitting of differential scanning calorimetry data. The start and end points of cure and the relationship between the dissipation factor and the degree of cure were obtained by comparing the dissipation factor from the dielectric properties with the degree of cure from the DSC data. The relationship between the dissipation factor and the degree of cure was tested under various temperature profiles.

Example study of the dissipation factor change according to the oil filtering in large oil-filled transformer (유입변압기 오일필터링에 따른 유전정접 변화사례 고찰)

  • Kong, Tae-Sik;Kim, Hee-Dong
    • Proceedings of the KIEE Conference
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    • pp.2035_2036
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    • 2009
  • This paper is purpose to understand the dissipation factor properties of the oil-filled large transformer according to the oil filtering. In order to know the insulation characteristic change by insulating oil filtering, we carried out the insulation diagnostic test for the same transformer before oil filtering and after. The insulation diagnosis tests are consist of the megger, the polarization index, the AC current test, the dissipation factor test and the partial discharge test, Especially we took notice of dissipation factor change, we analyzed and made a comparison of the two cases test result.

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Correlation of Piezocone Dissipation Results and Compression Index (피에조콘 소산결과와 압축지수의 상관관계)

  • Park, Young-Hwan;Kang, Beong-Joon;Lee, Jun-Hwan
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.1204-1211
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    • 2008
  • Compression index is one of the important characteristic numbers in soft soil engineering. Since 1940's, many researchers have suggested various practical solutions to define the compression index of clay using other soil properties. But, these results are only can give us an outline of soft soil behavior. In this study, the relationships between pore water pressure dissipation test results and compression index were suggested using comparison results of both tests. This relationships are based on basic concept of consolidation phenomena, essential difference between pore water pressure dissipation test and consolidation test, and disagreements between theoretical time factor and real time factor. To identify proportional factor of proposed equation, Geotechnical investigation results of Kwang-Yang(KY) site and Busan New Port(BN) site were used. The proportional factor was 0.0031 from 20 to 50% of consolidation rate where correlation parameter($R^2$) is 0.9051.

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On-line Cure Monitoring of Adhesive Joints by Dielectrometry (유전기법을 이용한 접착 조인트의 실시간 경화 모니터링)

  • 권재욱;진우석;이대길
    • Composites Research
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    • v.16 no.4
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    • pp.51-58
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    • 2003
  • Since the reliability of adhesively bonded joints is much dependent on the curing status of thermosetting adhesive, the on-line cure monitoring during the cure of adhesively joints could improve the quality of adhesively bonded joints. In this work, the dielectric method which measures the dissipation factor of the adhesive during the cure of joints and converts it into the degree of cure of the adhesive was devised. The relation between the dissipation factor and the degree of cure of adhesive was investigated, which could eliminate the temperature effect on the dissipation factor that is a strong function of the degree of cure and temperature of adhesive. From the investigation, it was found that the dissipation factor showed a trend similar to the cure rate of the adhesive.

Dielectric Cure Monitoring for Glass/Polyester Prepreg Composites (유리섬유/폴리에스터 복합재료를 위한 유전 경화 모니터링)

  • Kim, Hyoung-Geun;Kim, Jin-Kook;Lee, Dai-Gil
    • Proceedings of the KSME Conference
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    • pp.797-803
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    • 2001
  • The on-line cure monitoring of fiber reinforced thermosetting resin matrix composite material was performed for the better quality and productivity during manufacturing. Since the dissipation factor measured by dielectrometry method is dependent on the degree of cure and temperature of resin, in this study, a new method to obtain the degree of cure during on-line cure monitoring for glass/polyester composites was developed by employing a combination function of the temperature and the dissipation factor. Two sensor signals from a K-type thermocouple and an interdigitated dielectric sensor were processed during curing process under various cure cycles. The DSC (Differential Scanning Calorimetry) data was also used for the reference of degree of cure.

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Characteristics of Dissipation Factor in Large Generator Stator Bars (대용량 발전기 고정자 바의 유전정접 특성)

  • Kim, Hee-Dong;Kong, Tae-Sik;Ju, Young-Ho
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.402-403
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    • 2009
  • Accelerated aging tests were conducted under laboratory conditions on two generator stator bars. Electrical stress is applied in No. 1 model stator bar. Electrical and thermal stresses are applied in No. 2 model stator bar. As aging times increased from 0 to 11460h, dissipation factor($tan{\delta}$) test was performed on No. 1 and No.2 model stator bars. The ${\Delta}tan{\delta}$ of No. 1 and No. 2 stator bars increased with increased in aging time.

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Analysis of Insulation Condition in High Voltage Motor Stator Windings Following Cleaning and Insulation Reinforcement (세척과 절연보강에 따른 고압전동기 고정자 권선의 절연상태 분석)

  • Kim, Hee-Dong
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.25 no.6
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    • pp.474-480
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    • 2012
  • Diagnostic tests were performed on two high voltage(HV) motor stator windings. These tests included the measurement of insulation resistance, polarization index, AC current, dissipation factor($tan{\delta}$) and partial discharge(PD) magnitude. Surface contamination of HV motor stator windings has an effect on the AC current and $tan{\delta}$. When the stator windings were finished cleaning and insulation reinforcement, the increase rate of AC current(${\Delta}I$) and dissipation factor(${\Delta}tan{\delta}$) were very small compared to those before cleaning. However, the PD magnitude remained the same. These tests show that cleaning and insulation reinforcement of HV motor stator windings can reduce the insulation failure.