• 제목/요약/키워드: surface contamination

검색결과 927건 처리시간 0.039초

Effects of Contact Conditions on the Connector Electrical Resistance of Direct Current Circuits

  • Kim, Young-Tae;Sung, In-Ha;Kim, Jin-San;Kim, Dae-Eun
    • International Journal of Precision Engineering and Manufacturing
    • /
    • 제5권3호
    • /
    • pp.5-10
    • /
    • 2004
  • Electric contacts serve the purpose of transmitting electric signals across two conducting components. In this paper, the effects of contact conditions such as surface roughness, oxidation, and contamination were investigated with respect to electrical resistance variation of a connector in a direct current circuit. Such change in the electrical resistance is particularly important for low power circuits. The experimental results showed that compared with the effects of contact surface scratch or oxidation, the effect of contamination on the resistance variation was the most significant. In order to minimize failure due to electrical resistance change at the contact region, proper sealing to prevent contamination from entering the interface is needed.

배전용 폴리머애자의 섬락고장 (Flashover Failure of Polymer Insulator in Distribution Lines)

  • 한재홍;이병성;김찬영;윤태상
    • 한국전기전자재료학회:학술대회논문집
    • /
    • 한국전기전자재료학회 2000년도 하계학술대회 논문집
    • /
    • pp.767-770
    • /
    • 2000
  • This study was investigated for searching a cause of flashover failure of polymer insulator and preparing countermeasures. Hydrophobicity, microstructure and chemical structural change of polymer weathershed were studied by polymer characterization methods. In addition, the electrical properties such as power frequency dry flashover voltage/impulse voltage tests, contamination characteristics were carried out. The hydrophobicity of polymer weathershed was decreased significantly and cracks were observed on the surface. Also, the electrical characteristics did not satisfy the KEPCO specification. The failed polymer insulators showed the more leakage current than 4 years service-aged ones. From the result, it can be concluded that the flashover failure of polymer insulator was attributed to the surface aging and severe contamination.

  • PDF

ESDD 오손에 따른 송전용자기애자의 누설전류 파형의 분석 (Analysis of Leakage Current Waveforms for Transmission Line Porcelain Insulators due to ESDD Contamination)

  • 박재준
    • 전기학회논문지
    • /
    • 제61권10호
    • /
    • pp.1461-1470
    • /
    • 2012
  • This paper reports the contamination performance of transmission line porcelain insulators tested under five different contaminant conditions - clean and ESDD (equivalent salt deposit density) level (A, B, C, and D) through measurement of their leakage current under drop of potential method. To estimate the contamination for transmission line porcelain insulators, leakage current waveform and its maximum value were measured under step-up power test. In the clean insulators test, % distortion factors decreased with increasing step-up power, and as the ESDD level increased, some characteristics such as frequency analysis, harmonics and % distortion facotor could be used for contamination diagnosis of the transmission line porcelain insulators.

누설전류 측정을 통한 활선 절연물의 오손도 추정 (Estimation of Pollution Degree for Liveline Insulator with Leakage Current Measurement)

  • 심규일;최남호;박강식;한상옥
    • 대한전기학회:학술대회논문집
    • /
    • 대한전기학회 2001년도 하계학술대회 논문집 C
    • /
    • pp.1472-1474
    • /
    • 2001
  • In this paper, a method was presented to estimate the contamination degree of outdoor insulator by the measurement of surface leakage current. Contamination is one of the most important factor to determine the performance of insulator. Thus, it is very important to exam the contamination degree on the outdoor insulator. There are many limits, such as reliability of data, interval of measurement and similarity of environmental conditions, in conventional method. So, the estimation technique for contamination has been needed to monitor the accurate pollution degree of insulator in situ. In this investigation, phase difference was measured to compare the variance of phase difference with the contamination degree and relative humidity. From the result, we could confirm the capability of the estimation method.

  • PDF

Salt-fog 분무에 따른 실리콘 고무 애자의 표면열화 (Surface Degradation of Silicone Rubber Insulator by Salt-fog Test)

  • 장동욱;박영국;강성화;이용희;임기조
    • 한국전기전자재료학회:학술대회논문집
    • /
    • 한국전기전자재료학회 1999년도 추계학술대회 논문집
    • /
    • pp.509-512
    • /
    • 1999
  • The main problem in porcelain as a high voltage insulator is that the water film is felled on the insulator surface due to rain, flog, and dew. In the presence of contamination. leakage current increases which may lead to flashover that could be followed by an outage of the power system. These days, high voltage polymer outdoer insulators have been studied and widely used, because they have excellent electrical and mechanical properties, superior performance of flashover for contamination. light weight, easy installation or handling. no maintenance during service, competitive price, and so on. First of a1l the excellent performance of the silicone rubber in polluted and wet conditions is attributed to the ability of the material to maintain the hydrophobicity of the surface in the presence of severe contaminants and wet conditions. This is due to a low surface energy of the silicone rubber. But the leakage current and some surface discharge occurs on the surface of insulator when the insulator is used for a long time. So the leakage current and the surface discharge current are important lo estimate the condition of the silicone rubber surface. In this paper, the average leakage current the surface discharge current the surface rubber surface with the salt fog condition for the first stage.

  • PDF

수종의 치면열구 전색재의 전처리가 결합강도에 미치는 영향 (A STUDY ON THE INFLUENCE OF PRETREATMENT ON THE BOND STRENGTHS OF SOME PIT AND FISSURE SEALANTS)

  • 민윤경;정태성;김신
    • 대한소아치과학회지
    • /
    • 제25권2호
    • /
    • pp.277-284
    • /
    • 1998
  • For the purpose of comparing the shear bond strengths of pit and fissure sealants, and finding out the more efficient method of tooth surface treatment when the etched surface is contaminaed by saliva or moisture, an experiment was performed on 3 types of pit and fissure sealants. 120 extracted human molars were divided into 3 groups, each of which was composed of 40 specimens sealed with Helioseal, Teethmate-F and Fuji III respectively. And each groups was again divided into 4 subgroups according to tooth surface treatment. The shear bond strengths of each groups and subgroup was measured and statistically analyzed. The results obtained were as follows : 1. Shear bond strengths of nonfluoridated resin sealant, Helioseal were shown to be higher than those of fluoridated resin sealant, Teethmate-F, but, not significantly different. 2. Shear bond strengths of GI sealant, Fuji III were to be markedly lower than those of two resin sealants. 3. When there is moisture contamination, applying primer under sealant(Group IV) results in a significantly stronger bond strength of sealant to enamel than when using sealant alone(Group II) in case of all sealants. 4. When there is no moisture contamination, using primer under sealant (Group III) results in bond strength equivalent to bond strength on using sealant alone (Group I). 5. Based on the results above, it was demonstrated that the bond of sealant to tooth surface is greatly affected by saliva contamination and that the complete tooth isolation method should be fully emphasized. The application of primer is recommended when performing sealant under the environment very susceptible to saliva contamination.

  • PDF

여러 환경조건에 대한 고분자애자의 누설전류 특성 변화 (Variation in Leakage Current Characteristics of Polymer Insulator for Various Environmental Condition)

  • 박재준;최인혁;이동일
    • 한국전기전자재료학회논문지
    • /
    • 제19권2호
    • /
    • pp.169-175
    • /
    • 2006
  • This study investigated variation leakage current maximum value and waveform considering applied voltage phase angel by simulating three environmental conditions, such as fog, salt fog, and kaolin contamination .As the result of applied voltage phase angel characteristics, leakage currents presented almost in phases in the early stage regardless of environmental conditions just after applying the voltage, and the phase of leakage currents certain phase lags for the discharge of the applied voltage when surface discharges occurred due to the continuous environmental contamination. In addition, the difference in phase significantly increased according to the intensity of discharges. The change in distortion rates according to the environmental contamination presented a nearly same level just after applying the voltage. The distortion rate of third harmonic for the fundamental wave presented by the order of fog>salt fog>kaolin when surface discharges occurred due to the applied voltage for certain continued periods. In the case of the fog and salt fog, the scale of spectrums decreased according to the increase in frequencies from the results of the analysis of high frequencies. In addition, the even number frequency presented a relatively large level compared to the odd number frequency under the kaolin contamination.

HF-CT센서를 이용한 고분자애자의 오손특성 (Contamination Characteristics of Polymer Insulator using High Frequency Current Transformer)

  • 박재준
    • 정보학연구
    • /
    • 제8권4호
    • /
    • pp.1-7
    • /
    • 2005
  • Investigations of high frequency current transformer(HF-CT) waveform characteristics of the surface leakage on kaolin polluted EPDM polymer insulators have been performed. This work is part of a program aimed at examining the potential for HF-CT waveform characteristics analysis to provide information about the environment contaminants and environment condition of polymer insulators. The investigation reported examined the HF-CT waveform characteristics at high frequencies. The use of high frequency measurements for on-line applications reduces electrical inference. This work was peformed utilizing HF-CT to monitor of surface polluted discharge. It was found that HF-CT waveform frequency spectrum, magnitude depend on importantly the duration of the surface discharge activity.

  • PDF

Film Cassette의 세균 오염도와 소독에 관한 연구 (A Study on Contamination and Disinfection of Film Cassette)

  • 권대철;정경모;최지원
    • 대한방사선기술학회지:방사선기술과학
    • /
    • 제23권2호
    • /
    • pp.55-61
    • /
    • 2000
  • In July 2000, a bacteria infection on film cassette contact surface was examined at the diagnostic radiology department of the S. hospital. The objective of this study was to assess the contamination level on film cassette contact surface as a predictor of patient to prevent from nosocomial infection. The study showed that the laboratory result was identified non-pathologic bacterial in the four different cassette size of the contact surface. The study concludes that presence of a bacterial infection wilt prevent a using antiseptic technique on film cassette contact surface. Also the education of nosocomial infection for radiographer will be required.

  • PDF

철도차량 객차외측면 오염도 조사ㆍ분석 연구 (A Study on the Investigation and Analysis of the Passenger Car Surface Contamination)

  • 김용기;정우성;박덕신;이덕희
    • 한국철도학회:학술대회논문집
    • /
    • 한국철도학회 2000년도 춘계학술대회 논문집
    • /
    • pp.543-550
    • /
    • 2000
  • This study investigated and analysed the surface contaminant of the passenger car. Because the surface contaminants change the paint color of the passenger car, it is necessary to cleanse them for prolongating the maintenance period, Analysis method of the contaminant according to the kind of the passenger car, the line and the part of the train are systemized. Contamination mechanism and deterioration reason of paint colors on the surface of passenger car are studied. We expect that results of this study could contribute to providing of a fundamental research data, which is necessary for the development of a low-pollution passenger car cleanser.

  • PDF