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吳年浩(Yeon-Ho Oh),宋基東(Ki-Dong Song),鄭鎭敎(Jin-Kyo Chong) 대한전기학회 2008 전기학회논문지 Vol.57 No.1
Extra-high voltage(EHV) disconnecting switch(DS) consists of the electrical contacts and mechanical parts which actuate the contacts. When the short-circuit condition occurs, a large amount of current flows through the electrical contact in disconnecting switches and this causes considerable temperature rise due to Joule heating. If the temperature rise is higher than the melting point of contact material, the DS contact becomes melting and cannot be usable anymore. For this reason, the analysis for capability of carrying short-circuit current in DS contacts must be performed at a design stage. Here, we proposed a numerical technique for evaluating the capability of carrying short-circuit current at electrical contacts in EHV DS. In this numerical approach, the mechanical and thermal analyses were simulated to check the capability of carrying short-circuit current. First, the applied pressure at contact parts was analyzed considering the mechanical properties, and then contact resistance was calculated by an empirical equation. Finally, thermal analysis was performed with resistance variation at electrical contacts. To verify these numerical results, the distributions of temperature in DS were experimentally measured and compared with each other. The results from experiments were agreed well with those from the proposed numerical simulations.
김중경(Joong-Kyoung Kim),오년호(Yeon-Ho Oh),이지연(Ji-Yeon Lee),한성진(Sung-Chin Hahn) 대한전기학회 2009 전기학회논문지 Vol.58 No.4
Many works on the temperature distribution of power apparatus have usually done by coupled magneto-thermal analysis. Such a method can not consider the internal gas or oil flow in the power apparatus such as gas insulated switchgear, GIS bus bar, and power transformer. Moreover it can not show the internal temperature distribution of the power apparatus exactly. This paper proposes a coupled magneto-thermal-flow analysis considering Navier-Stokes equations. The convection heat transfer coefficient is calculated analytically by applying Nusselt number for natural convection and is applied to the boundary condition of proposed method. Temperature distribution of the GIS bus bar model considering thermal flow is obtained by the proposed method and shows good agreement with the experimental data.
宋基東(Ki-Dong Song),吳年浩(Yeon-Ho Oh),鄭鎭敎(Jin-Kyo Chong),趙龍成(Young-Sung Cho) 대한전기학회 2007 전기학회논문지 Vol.56 No.12
A special PM - Tube(Photo Multiplier Tube) that is using the photoelectric effect has been designed and manufactured to measure the radiation energy of arc in a gas circuit breaker(GCB). The PM-Tube, LLG(liquid light guides), ND(neutral density) filter, and a model gas circuit breaker have been combined for the reception and the transmission of the light and a simplified synthetic test facility with the arc energy measuring system has been established. In the case of SF? gas pressure 5㎏.f/㎠ and arc length 20㎜, the radiation energy increases with the arc current but it tend to be saturated in the above 20㎄. Under the arc current 20㎄, the total radiation energy has the biggest value around 8㎄ and was not exceeded 40% of the total arc energy.
宋基東(Ki-Dong Song),吳年浩(Yeon-Ho Oh),鄭鎭敎(Jin-Kyo Chong),趙龍成(Yong-Sung Cho) 대한전기학회 2006 전기학회논문지 B Vol.55 No.11
This paper presents the measured radiation intensity of high-pressure and large-current arc with the current. In order to measure the radiation intensity of large-current arc, a model circuit breaker was specially designed and manufactured and the method using an astronomical telescope was utilized after various measuring methods were investigated, A trigger system was designed and fabricated to coincide the time of desired current with the exposure time of 1㎳ of the spectroscope. A high-speed camera was used to investigate the shape and behavior of the arc and the captured results have been used to calculate the radiation energy. The calculated arc temperature with Boltzmann plot method using the measured radiation intensity have 18, 000 ~ 27, 000 K to the current 4㎄ ~ l5㎄ And also, using the calculated arc temperature and the captured arc shape the radiation energy of the current 5㎄ ~ 15㎄ were calculated with 8×10? ~ 4.0×10? W/m respectively.
宋基東(Ki-Dong Song),鄭鎭敎(Jin-Kyo Chong),吳年浩(Yeon-Ho Oh),李佑暎(Woo-Young Lee) 대한전기학회 2006 전기학회논문지 B Vol.55 No.10
After various measuring methods and system were investigated. Rogowski colis for the measurement of parameters in current zero region were designed and manufactured. Using the Rogowski coils and a 38㎸ 40㎸ VCB(vacuum circuit breaker), at last the post-arc current has been successfully measured firstly. It was found that the Rogowski coils used in this study have good characteristics and propriety to measure the parameters of current zero. We realized that the data processing for evaluating the post-arc current from the experimental results needs much more careful attention than that for building the measuring technique and system. The magnitude of post-arc current and the falling time of it to zero are proportioned to the rate of current di/dt. The magnitude of post-arc currents were around 1~3A to the interruption current of 20~30㎸ in the model VCE.
金烘?(Hong-Kyu Kim),宋基東(Ki-Dong Song),鄭鎭敎(Jin-Kyo Chong),吳年浩(Yeon-Ho Oh),朴敬燁(Kyong-Yop Park) 대한전기학회 2006 전기학회논문지 B Vol.55 No.10
To analyze the small current interruption performance for the gas circuit breakers, the gas density and electric field intensity should be calculated. In this paper, the FVFLIC method is used for the gas flow analysis and the FEM for the electric field analysis. Then, the dielectric withstanding voltage is evaluated by the empirical formulation or Streamer theory. By comparing the calculated dielectric strength with the test result, it is found that both methods show good prediction capability for the small current interruption performance. Especially, when both methods predict the same interrupting performance, the prediction is in accordance with the experimental result.