폴리머 housing 형 피뢰기의 개발과 특성 평가

조한구,김인성 ( Han Goo Cho,In Sung Kim ) 한국전기전자재료학회 1997 한국전기전자재료학회 춘계학술대회논문집 Vol.1997 No.0

내부쉴드 구조에 따른 컴팩트한 폴리머 부싱 설계에 관한 연구

조한구,유대훈,강형경,Cho, Han-Goo,Yoo, Dae-Hoon,Kang, Hyung-Kyung 한국전기전자재료학회 2009 전기전자재료학회논문지 Vol.22 No.5

This paper describes a study on the design of compact polymer bushing with inner control shield. In the bushing, a high electric stress occurred between field shaper and central conductor by the closely space. Also coaxial cylindrical shield has a great height along the axis to control an electric field. Consequently, all the potentials are raised axially along the field shaper and electric stress is concentrated on a part of the surface of the FRP tube near the upper end of the field shaper. In accordance, the field control can be achieved by means of the designs of such inner control shields. The floating and ring shield designs was decreased electric field concentration at critical parts of the bushing. The shield gaps is formed between field shaper and ring shield. Accordance equipotential lines extend through gaps. As a result, the resulting electrical stress are thus reduced in the range $17{\sim}23%$ in the bushing with floating and ring shield designs. Maxwell 2D simulator based on the boundary element method was also introduced in order to verify the reliability of the polymer bushing. The optimized design uses internal elements for electric stress grading at critical parts of the bushing.

계면활성제가 첨가된 염수용액에 따른 폴리머 애자의 트래킹 성능 평가

조한구,이운용,한동희,강성화,최인혁,임기조,Cho, Han-Goo,Lee, Un-Yong,Han, Dong-Hee,Kang, Sung-Hwa,Choi, In-Hyuk,Lim, Kee-Joe 한국전기전자재료학회 2005 전기전자재료학회논문지 Vol.18 No.1

Recently, polymer insulators that are used for high voltage applications have some advantages such as light weight, small size, vandalism resistance, hydrophobicity and easy making process. During outdoor service of polymer insulators, the surface of the insulating material is frequently subjected to moisture and contamination that lead to dry band arcing. Their tracking resistance, erosion resistance, end sealing and shed design are very important because dry band arcing causes degradation of polymer surface. Aging test to estimate life property of polymer insulator is executed through several international standard such as IEC 61109 and CEA tracking wheel test, but is not getting clear conclusion yet. There are two methods in the diagnosis method of polymer insulator such as off-line and on-line. The diagnosis methods in off-line are external condition analysis by the eye, contaminant analysis on surface, surface analysis, pollution withstand voltage test, power frequency flashover voltage test, lightning impulse flashover test, tensile fracture load test and flexural load test. Polymer material is also investigated it's tracking resistance by adding surface active agent in IEC 587. In this paper, the tracking performance of polymer insulator with salt solution which is added surface active agent. The diagnosis of insulator sample has been analyzed by leakage current and visual examination, STRI guide and thermal image camera.

고분자 절연재료의 트랙킹 열화에 미치는 오손액의 영향

조한구,박용관 ( Han Goo Cho,Yong Kwan Park ) 한국전기전자재료학회 1997 전기전자재료학회논문지 Vol.10 No.8

초고압 피뢰기용 ZnO 소자의 장시간 방전내량 특성 평가

조한구,윤한수,김석수,Cho, Han-Goo,Yun, Han-Soo,Kim, Seok-Soo 한국전기전자재료학회 2006 전기전자재료학회논문지 Vol.19 No.4

This paper describes the evaluation of the long duration current impulse withstand characteristics of ZnO blocks for high voltage surge arresters. Four ZnO varistors were manufactured with the general ceramic production method and the long duration current impulse withstand test, electrical uniformity evaluation test and microstructure observation were performed. All varistors exhibited high density, which was in the range of $5.42{\sim}5.46g/cm^3$. In the electrical properties, the reference voltage of samples was in the range of $5.11{\sim}5.25\;kV$ and the residual voltage was in the range of $8.314{\sim}8.523\;kV$. In the long duration current impulse withstand test, sample No.2 and No.3 failed at the 2nd and 4th shot of series impulse currents, respectively, but the rest survived 18 shots during the test. Before and after this test, the variation ratio of the residual voltage of samples survived was below 0.5 %, which was in the acceptance range of 5 %. According to the results of the test, it is thought that if the soldering method is improved, ZnO varistors would be possible to apply to the high voltage arresters like the station class and transmission line arresters in the near future.

폴리머 피뢰기의 구조에 따른 온도와 누설전류 특성

조한구,유대훈,이운용,김하나,Cho, Han-Goo,You, Dae-Hoon,Lee, Un-Yong,Kim, Ha-Na 한국전기전자재료학회 2007 전기전자재료학회논문지 Vol.20 No.3

In this paper, the ZnO surge arrester performance of power distribution class has been studied under different manufacturing conditions such as housing materials(polymeric, porcelain), interface sealants and one-body molding type. In the recent years, the polymeric ZnO surge arresters have been developed and put into operations based on their excellent characteristics. For polymeric surge arresters, the inner gas volume is extremely small, especially in solid insulation polymeric arresters there are not any gas volume inside arresters in the structure due to polymeric materials are filled into the internal gas volume. The sealing integrity is related to safe operation of surge arrester, the prime failure reason of porcelain housed arresters is moisture ingress. In this paper, the sealing integrity of polymeric surge arresters is investigated with moisture multi-aging test and ingress test. The evaluation techniques are used to inspect the sealing integrity of polymeric arresters, including leakage current, surface temperature, reference voltage and dissipation factor.

Rotating Wheel Dip Test에 의한 에폭시 절연재료의 내트래킹성과 열화 특성

조한구,Cho, Han-Goo 한국전기전자재료학회 2008 전기전자재료학회논문지 Vol.21 No.6

This paper describes the results of a study on the tracking performance of outdoor insulating materials based on the rotating wheel dip test(RWDT). And, the influence of surface degradation was evaluated through such as measurement of the flashover voltage after and before tracking test, also aspects of surface degradation using scanning electron microscopy. The time to tracking breakdown of treated filled specimen is longer than untreated filled specimen. And, after the RWDT, the surface of specimen by adding untreated filler appeared heavy erosion. It was found that the addition to surface treated filler, the better tracking resistance. In the RWDT, the breakdown specimen is not affected by the dry flashover voltage, despite the fact that the surface degradation of tracking test has different state on each specimen. This suggests that wet flashover voltage play an important role in evaluating of tracking and erosion on the surface degradation in tracking test. And, the flashover voltage of specimen under wet conditions are greatly affected by the salt concentration and degree of degradation by the RWDT Because of hydrophobicity and degree of degradation by the RWDT, the flashover voltage of treated filled specimen is higher than that of untreated filled specimen. Different types of specimen may have different hydrophobicity and their surface state under contaminated conditions may not be the same.

Series Gap Type 피뢰기의 뇌임펄스 동작책무 및 온도의존성에 관한 연구

조한구,유대훈,Cho, Han-Goo,Yoo, Dae-Hoon 한국전기전자재료학회 2009 전기전자재료학회논문지 Vol.22 No.8

This paper describes lightning impulse operating duty performance and temperature dependence of series gap type for transmission line arresters. The ageing parameters of lightning arresters are impulse current, moisture ingress, temperature ageing and so on. Especially it is important to estimate the change of electrical characteristics by lightning impulse current. In the discharge withstand test, total energy applied to the ZnO arrester each time is 4/10 ${\mu}s$, 30 kA. and in the operating duty test, the arrester has passed the test if thermal stability is achieved, if the residual voltage measured before and after the test is not changed by more than 5 %, and after the test reveals no evidence of puncture, flashover or cracking of the ZnO block. As a results, the residual voltage was in the range of 17.2${\sim}$20.3 kV and ZnO block bear up against at 2 shot of series impulse current of 30 kA. Also it was so excellent that the mechanical destruction does not occur at the 2 groups of 5 impulses current of 2/20 ${\mu}s$ 10 kA. According to the tests, it is thought that the ZnO arrester shows good stability with impulse current test. and it was found that the ambient temperature is increased resistive leakage current was increased in the range 47.3${\sim}$167.4 ${\mu}A$.

일체형 주상용 몰드 변압기의 온도분포 및 특성 비교

조한구,이운용,강택수,최인혁,Cho, Han-Goo,Lee, Un-Yong,Kang, Tack-Sou,Choi, In-Hyuk 한국전기전자재료학회 2006 전기전자재료학회논문지 Vol.19 No.12

The mold transformers have been widely used in underground substations of large building and have some advantages when compared with oil-transformer. Those advantages are low fire risk, environmental compatibility, compact size and high reliability. The mold transformer is generally known to have cooling duct between low voltage and high voltage coil. To achieve better compact structure and low loss, mold transformers made by one body molding method has been developed. Nevertheless, such kinds of transformer need better cooling method because heat radiation between each winding is still of problem. The life of transformer is significantly dependent on the thermal behavior in windings. Many designers have calculated temperature distribution in transformers and hot spot point by finite element method(FEM) to analyze winding temperature rise. In this paper, the temperature distribution analysis of 100 kVA pole mold transformer for power distribution were investigated by FEM program and the thermal analysis results were compared with temperature rise test.

열-기계적 스트레스가 폴리머 피뢰기의 전기적 특성에 미치는 영향

조한구,유대훈,Cho, Han-Goo,You, Dae-Hoon 한국전기전자재료학회 2007 전기전자재료학회논문지 Vol.20 No.6

This paper describes the results of a study on the sealing integrity of polymer housed surge arrester based on the thermal mechanical test. The polymer housed surge arrester employs silicone insulating materials for its housing, instead of the conventional porcelain housing. The polymer housed surge arresters exhibited the highest sealing integrity because it is not air volume between the FRP(fiber reinforced plastics) module and the silicone housing. In accordance, the sealing integrity of station class surge arresters is investigated with moisture ingress test. And, the influence of sealing integrity was evaluated through such as measurement of the deflection, reference voltage, leakage current. In electrical characteristics, reference voltage decreased in the range of $16.45{\sim}16.15\;kV$ with after thermal mechanical test. In contrary, despite the continued moisture ingress, the polymer housed surge arresters exhibited almost the same leakage current value and the resistive leakage current has risen slightly. As a results, It was thought that the polymer housed surge arresters shows good stability with sealing integrity.