• Title/Summary/Keyword: temperature rise test

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Insulation Characteristics and Thermography Diagnosis of Porcelain Insulators for the Distribution Systems (배전용 자기재 현수애자의 절연특성과 열화상 진단)

  • Joung, Jong-Man;Kim, Dong-Myeong;Choi, Myung-Ho
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.60 no.4
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    • pp.267-271
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    • 2011
  • The insulating characteristics and temperature rise behaviors of porcelain suspension insulators were investigated. The testing insulators had used in the distribution systems normally and were sampled. Firstly, leakage current was measured and its impedance was calculated. The leakage current of good insulators is 0.2 mA and its impedance is 66 $M{\Omega}$. The worse insulators have lower impedance and the insulators having below 15 $M{\Omega}$ take place flashover at the high frequency voltage flashover test. Secondly, the temperature rise characteristics were analyzed depending on leakage current and its impedance. Surface temperature of insulators was measured for 30 minutes and until its saturation after voltage was applied. The temperature rise of insulators having 15 $M{\Omega}$ is about $14.5^{\circ}C$ above the ambient temperature. Lastly, the heating behaviors of 3 insulators in a string was analyzed. Any insulator in the string does not generate heat so far as it has at least one sound insulator. On the other hand, all the insulators in the string are bad if the string have any heating insulator.

A Change in the Temperature and Infrared Radiation as a Variation of Irradiance (복사조도의 번동에 따른 온도 및 적외선복사량의 변화)

  • Han, Jong-Sung;Kim, Gi-Hoon;Kim, Hoon
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.19 no.2
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    • pp.28-34
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    • 2005
  • Thermal reactions by infrared radiation brings about physical damage by temperature rise process or temperature drop process of the material. In this study, a measuring system was set up to measure the temperature rise of each sample by infrared radiation from light source. And the temperature rise of the samples and amount of infrared radiation by various light source were measured with varying irradiance. On the basis of the result from the test, we analyzed a functional relation between infrared and infrared radiation.

A Study on the Development of Standardization Tester for the Field Inspection of the Rate of Rise Spot Type Heat Detector (차동식스포트형열감지기 현장점검용 표준화기기 개발에 관한 연구)

  • Kim, Shi-Kuk;Yuk, Hyun-Dai;Yang, Seung-Hyun;Jee, Seung-Wook;Lee, Chun-Ha
    • Fire Science and Engineering
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    • v.23 no.3
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    • pp.85-92
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    • 2009
  • This paper studied on the development of standardization tester for the field inspection of the rate of rise spot type heat detector. It was to find the problems of the 4 type's testers such as A type (electric bulb type), B type (halogen lamp type), C type (heating coil type), D type (fumigator type) which were used to check of the rate of rise spot type heat detector in inspection for the fire protection. To identify those problems, this paper described about the development of standardization tester for the field inspection of the rate of rise spot type heat detector and that have the function of auto setting temperature more $30^{\circ}C$ higher than room temperature and keep the constant temperature. And keep the constant wind velocity of 85cm/sec. Performance verification results of the developed prototype that had same conditions such as the sensitivity test conditions at the type approval of the rate of rise spot type heat detector.

Study on Influences and Elimination of Test Temperature on PDC Characteristic Spectroscopy of Oil-Paper Insulation System

  • Liu, Xiao;Liao, Ruijin;Lv, Yandong;Liu, Jiefeng;Gao, Jun;Hao, Jian
    • Journal of Electrical Engineering and Technology
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    • v.10 no.3
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    • pp.1107-1113
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    • 2015
  • Test temperature is an important factor affecting the measurement results of dielectric response of field power transformers. In order to better apply the polarization and depolarization current (PDC) to the condition monitoring of oil-paper insulation system in power transformers, the influences and elimination method of test temperature on PDC characteristic spectroscopy (PDC-CS) were investigated. Firstly, the experimental winding sample was measured by PDC method at different test temperatures, then the PDC-CS was obtained from the measurement results and its changing rules were discussed, which show that the PDC-CS appears a horizontal mobility with the rise of temperature. Based on the rules, the “time temperature shift technique” was introduced to eliminate the influence of test temperature. It is shown that the PDC-CS at different test temperatures can be converted to the same reference temperature coincident with each other.

Correcting Stress-Strain Curves of Nimonic 80A Alloy based on Direct Measurement of Barreling and Heat Generation (압축시험에서의 배럴링 및 소성발열 직접 측정에 의한 Nimonic 80A 합금의 응력-변형률 선도 보정)

  • S.H. Kang;H.W. Jung;H. Lee;S.J. Kim;Y.S. Oh;J. Jung;S. Oh;H. Kim
    • Transactions of Materials Processing
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    • v.32 no.4
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    • pp.215-220
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    • 2023
  • In this study, the correction process of stress-strain curves obtained from hot compression test is introduced since the barreling induced by friction and adiabatic heat generation induced by plastic work occur under high strain rate. A shear friction factor was quantitatively estimated by measuring the dimension of barreling and temperature rise due to adiabatic heat generation was directly measured during compression test. Thereafter, the stress-strain curves were re-evaluated by introducing several equations to correct the effects of the friction and temperature rise. It was found that adiabatic factor at strain rate of 10/s is in the range of about 0.5 to 0.75 for Nimonic 80A and decreases as the assigned temperature increases.

A Study on Developing the Magnetic Wedge Material and its Application (자성웨지 국산화 개발 및 그 적용에 관한 연구)

  • Choi, Jong-Koo;Kang, Yi-Kuk;Bae, Byeong-Choon;Hong, Sung-Il
    • Proceedings of the KIEE Conference
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    • 1996.07c
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    • pp.1482-1484
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    • 1996
  • To apply Magnetic wedges to the motor, comparing with not applying, showes its performance change of efficiency increse, reduction of temperature rise, harmonics, and magnetic noise. The motor specification and test condition are 37kW-4P-380V-60Hz,squirrel-cage, three phase induction motor with semiclosed type slots. The result of load test to compare with nonmagnetic wedges showed 1.5% increment of efficiency at 100% load and $8.0^{\circ}C$ decrement of temperature rise at stator coil. And for developing the magnetic wedge matrial, its manufacturing process was setting and TG-DTA, optical microscope, SEM, bending strength and permeability were investigated into the material made of through the process.

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Fire Test of Fiber Cocktail Reinforced High Strength Concrete Columns with Loading (섬유혼입공법을 적용한 고강도콘크리트 기둥의 재하 내화시험)

  • Youm, Kwang-Soo;Jeon, Hun-Kyu;Kim, Heung-Youl
    • Journal of the Korea Concrete Institute
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    • v.21 no.4
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    • pp.473-480
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    • 2009
  • The 180 minutes fire test based on the standard curve of ISO-834 were conducted on three RC column specimens with different constant axial loading ratios to evaluate the fire performance of fiber cocktail (polypropylene+steel fiber) reinforced high strength concrete column. The columns were tested under three loading levels as 40%, 50%, and 61% of the design load. No explosive spalling has been observed and the original color of specimen surface has been changed to light pinkish grey. The maximum axial displacements of three specimens were 1.5~2.2 mm. There was no reduction in load bearing capacity of each specimen exposed to fire and no effect were observed on the fire performance within 61% of the design load. The tendencies of the results with loading, such as the temperature distribution of in concrete and the changes in temperature rise due to the water vaporization in concrete, are very similar to those without loading. The final temperatures of steel rebar after 180 minutes of fire test resulted in 491.4${^{\circ}C}$ for corner rebar, 329.0${^{\circ}C}$ for center rebar, and 409.8${^{\circ}C}$ for total mean of steel rebar. The difference of mean temperature between corner and center rebar was 153.7${^{\circ}C}$ㅍ. The tendency of temperature rise in concrete and steel rebar changed after 30~50 minutes from the starting time of the fire test because the heat energy influx into corner rebar is larger than that into center rebar. The cause of decrease in temperature rise was due to the water vaporization in concrete, the lower temperature gradient of the concrete with steel and polypropylene fiber cocktails, the moisture movement toward steel rebars and the moisture clogging.

Microstructure and High Temperature Strength of Rapidly Solidified Al-8wt%Fe Alloy (급속응고된 Al-8wt%Fe 합금의 미세조직 및 고온강도)

  • 최병준
    • Journal of Powder Materials
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    • v.5 no.3
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    • pp.192-198
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    • 1998
  • Microstructure and mechanical properties were examined on rapidly solidified Al-8wt%Fe alloy. High temperature strength test was also undertaken, and it is shown that the refinement in microstructure resulting from extremely rapid cooling rates gives rise to improved high temperature strength, but the elongation to fracture of this material decreases with increasing temperature, particularly in the temperature range up to 30$0^{\circ}C$. Specimens heat-treated for 100 hrs were analyzed with TEM micrographs to understand the thermal stability of this material.

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Fire Test of Fiber Cocktail Reinforced High Strength Concrete Columns without Loading (섬유혼입공법을 적용한 고강도콘크리트 기둥의 비재하 내화시험)

  • Youm, Kwang-Soo;Jeon, Hun-Kyu;Kim, Heung-Youl
    • Journal of the Korea Concrete Institute
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    • v.21 no.4
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    • pp.465-471
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    • 2009
  • To prevent the explosive spalling of the high strength concrete and control the rise of temperature in the steel rebar during fire, a fiber cocktail method has been proposed simultaneously with the use of polypropylene and steel fiber. After applying the fiber cocktail (polypropylene and steel fibers) into the mixture of high strength concrete with a compressive strength of between 40 and 100 MPa and evaluating the thermal properties at elevated temperatures, the fire test was carried out on structural members in order to evaluate the fire resistance performance. Two column specimens were exposed to the fire without loading for 180 minutes based on the standard curve of ISO-834. No explosive spalling has been observed and the original color of specimen surface was changed to light pinkish grey. The inner temperature of concrete dropped rapidly starting from 60mm deep. After 60 minutes of exposure to the fire, the temperature gradient of fiber cocktail reinforced high strength concrete was measured as 2.2oC/mm, which is approximately 5 times less than that of normal concrete. The final temperatures of steel rebar after 180 minutes of fire test resulted in 488.0oC for corner rebar, 350.9oC for center rebar, and 419.5oC for total mean of steel rebar. The difference of mean temperature between corner and center rebar was 137.1oC The tendency of temperature rise in concrete and steel rebar changed between 100oC and 150oC The cause of decrease in temperature rise was due to the water vaporization in concrete, the lower temperature gradient of the concrete with steel and polypropylene fiber cocktails, the moisture movement toward steel rebars and the moisture clogging.

An Experimental Study on Hydration Heat Characteristics for Thermal Crack Analysis Based on FEM of Urea Mixed Mass Concrete (Urea 혼입 매스콘크리트의 FEM 온도균열 해석을 위한 수화발열특성에 관한 실험적 연구)

  • Mun, Dong-Hwan;Jang, Hyun-O;Lee, Han-Seung
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2019.05a
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    • pp.36-37
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    • 2019
  • In domestic construction industry progress, construction and quality control of large structures are considered to be important as the superstructure and mass scale of structures. In the case of mass concrete, high hydration heat caused by cement hydration generates temperature stress by generating internal temperature difference with the concrete surface. These temperature stresses cause cracks to penetrate the concrete structure. A method of lowering the heat generation by incorporating Urea in order to reduce the concrete temperature crack has been proposed. In this study, the heat function coefficient for the FEM temperature crack analysis of the mass concrete containing the element was derived and the adiabatic temperature rise test was carried out according to the incorporation of the element. As a result of this experiment, the maximum temperature of 41 ± 1℃ was obtained irrespective of the amount of urea, and the maximum temperature decreased by 16.9℃ in concrete containing 40kg/㎥ of urea.

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