• Title, Summary, Keyword: Gas circuit breaker

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A Study on A Gas Circuit Breaker Development Using Simplified Synthetic Testing Facility (간이합성시험설비를 이용한 가스차단기 개발에 관한 연구)

  • Chong, Jin-Kyo;Kim, Gyu-Tak
    • Proceedings of the KIEE Conference
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    • pp.902-904
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    • 2007
  • A $SF_6$ gas circuit breakers are widely used for short circuit current interruption in EHV or UHV power system. During a $SF_6$ gas circuit breaker development, Simplified synthetic testing facility is used. This paper shows how simplified synthetic testing facility is used for a SF6 gas circuit breaker development.

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Analysis of Dielectric Breakdown of Hot SF6 Gas in a Gas Circuit Breaker

  • Kim, Hong-Kyu;Chong, Jin-Kyo;Song, Ki-Dong
    • Journal of Electrical Engineering and Technology
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    • v.5 no.2
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    • pp.264-269
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    • 2010
  • This paper presents the analysis of the dielectric characteristics of a hot $SF_6$ gas in a gas circuit breaker. Hot gas flow is analyzed using the FVFLIC method considering the moving boundary, material properties of real $SF_6$ gas, and arc plasma. In the arc model, the re-absorption of the emitted radiation is approximated with the boundary source layer where the re-absorbed radiation energy is input as an energy source term in the energy conservation equation. The breakdown criterion of a hot gas is predicted using the critical electric field as a function of temperature and pressure. To validate the simulation method, breakdown voltage for a 145kV 40kA circuit breaker was measured for various conditions. Consistent results between the simulation and experiment were confirmed.

Study of the Compressible Nozzle Flow in a Gas Circuit Breaker (가스차단기의 소호노즐 내부에서 발생하는 압축성 유동에 관한 연구)

  • Jung Sung-Jae;Kim Heuy-Dong
    • Proceedings of the KSME Conference
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    • pp.123-126
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    • 2002
  • Very frequently the compressible flow in an extinction nozzle of gas circuit breaker is simulated under no arc assumption, which can be reasonable for both high and low current breakings. In the present study, computations are performed to investigate the major features of the compressible flows inside the arc extinction nozzle of gas circuit breaker. A fully implicit finite volume scheme is applied to solve the two-dimensional, steady, compressible, Wavier-Stokes equations. The computed results are validated with the previous experimental data available. Several types of turbulence models are explored to reasonably predict the complicated flows inside the arc extinction nozzle. The obtained results show that the shock wave boundary layer interaction inside the nozzle significantly influences the whole performance of the gas breaker.

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Influence of SF6/N2 Gas Mixture Ratios on the Lightning Streamer Propagation Characteristics of 22 kV MV Circuit Breaker

  • Gandhi, R.;Chandrasekar, S.;Nagarajan, C.
    • Journal of Electrical Engineering and Technology
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    • v.13 no.4
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    • pp.1663-1672
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    • 2018
  • In recent times, gas insulated medium voltage (MV) circuit breakers (CB) form a vital component in power system network, considering its advantages such as reduced size and safety margins. Gas insulation characteristics of circuit breakers are generally measured by lightning impulse (LI) test according to IEC standard 60060-1 as a factory routine test. Considering the environmental issues of $SF_6$ gas, many research works are being carried out towards the mixture of $SF_6$ gases for high voltage insulation applications. However, few reports are only available regarding the LI withstand and streamer propagation characteristics (at both positive and negative polarity of waveform) of $SF_6/N_2$ gas mixture insulated medium voltage circuit breakers. In this paper, positive and negative polarity LI tests are carried out on 22 kV medium voltage circuit breaker filled with $SF_6/N_2$ gas mixture at different gas pressures (1-5 bar) and at different gas mixture ratios. Important LI parameters such as breakdown voltage, streamer velocity, time to breakdown and acceleration voltage are evaluated with IEC standard LI ($1.2/50{\mu}s$) waveform. Weibull distribution analysis of LI breakdown voltage data is carried out and 50% probability breakdown voltage, scale parameter and shape parameter are evaluated. Results illustrate that the $25%SF_6+75%N_2$ gas filled insulation considerably enhances the LI withstand and breakdown strength of MV circuit breakers. LI breakdown voltage of circuit breaker under negative polarity shows higher value when compared with positive polarity. Results show that maintaining the gas pressure at 0.3 MPa (3 bar) with 10% $SF_6$ gas mixed with 90% $N_2$ will give optimum lighting impulse withstand performance of 22 kV MV circuit breaker.

A Study On The Arc Resistance of $SF_6$ Gas Circuit Breaker ($SF_6$ 가스차단기의 아크저항에 관한 연구)

  • Chong, Jin-Kyo;Lee, Woo-Young;Kim, Gyu-Tak
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.56 no.9
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    • pp.1566-1570
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    • 2007
  • [ $SF_6$ ] gas circuit breakers are widely used for short circuit current interruption in EHV(Extra High Voltage) or UHV(Ultra High Voltage) power systems. To develop $SF_6$ gas circuit breakers, the arc resistance value is necessary to compare experimental results to numerical ones. The arc resistance value can be obtained from a breaking test with a $SF_6$ gas circuit breaker. The direct testing or synthetic testing facility is widely used to verify the breaking ability for $SF_6$ gas circuit breakers. We employed the simplified synthetic testing facility to test a $SF_6$ gas circuit breaker prototype. The arc resistance characteristic was measured and calculated under the various experimental conditions. This arc resistance value can be used for verifying the numerical results from arc simulation in a circuit breakers.

Analysis of Withstand Voltage between Arc Contacts of High Voltage SF6 Gas Circuit Breaker n Making Operation (초고압 SF6 가스 차단기 투입 시 아크접촉자 내전압 특성 연구)

  • Kim, In-Gil;Lee, Joo-Hyun;Jung, Hyung-Su;Park, Jae-Yoon
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.61 no.4
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    • pp.601-605
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    • 2012
  • The non-controlled closing of High-voltage SF6 gas circuit breaker can cause transient current and overvoltage in the field. The controlled closing technology is an effective way to reduce transient current and voltage, prevent equipment failures, and improve power quality. For the development of controlled closing, it is obviously necessary to determine the withstand voltage between arc contacts of High-voltage SF6 gas circuit breaker in making operation. This paper focuses on decrease of pressure and density of SF6 gas that can affect withstand voltage between arc contacts in making operation. The dielectric strength between arc contacts could be improved by minimizing the decrement of pressure and density of SF6 gas obtained by simulation and test and moreover the rate of decrease of dielectric strength (RDDS) of arc contacts could be foreseen.

Analysis of the Cold Gas Flow in Puffer Type Circuit Breaker (Puffer식 차단기 내의 냉가스 유동 해석)

  • Kim, Hong-Gyu;Sin, Seung-Rok;Jeong, Hyeon-Gyo;Kim, Du-Seong;Gwon, Gi-Yeong
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.49 no.4
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    • pp.233-239
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    • 2000
  • There are many difficult problems in analyzing the gas flow in puffer type circuit breaker such as complex geometry, moving boundary, shock wave and so on. To predict the interruption performance accurately, these should be considered in the simulation. In this paper, the analysis procedure of the cold gas flow in the circuit breaker is presented. Euler equation is solved by FVFLIC method which is an explicit time difference scheme for an unsteady flow computation. Moving boundaries are treated with a cell elimination-addition technique. The pressure and density in front of piston are calculated from the rate of the cell volume change. The presented method is applied to the real circuit breaker model and the pressure in front of the piston is good agreement with the experimental one.

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Investigation of Small Current Interruption Performance for New Type of Interrupting Chamber in SF$_{6}$ Gas Circuit Breaker (신차단방식 SF$_{6}$ 가스 차단기의 소전류 차단성능 연구)

  • Song, Won-Pyo;Kweon, Ki-Yeoung;Lee, Jae-Sung;Song, Ki-Dong;Kim, Maeng-Hyun;Ko, Hee-Seok
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.54 no.11
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    • pp.519-526
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    • 2005
  • This paper presents computer simulation results for developing new type of SF$_{6}$ Circuit Breaker in terms of cold gas flow after small current interruption. This cold gas flows down a nozzle into the chamber of a circuit breaker. There are many difficult problems in analyzing the gas flow due to complex geometry, moving boundary, shock wave and so on. When predicting the dielectric capability of a gas circuit breaker after interruption, the gas pressure and density distributions due to the cold gas must be considered in addition to the electrical field imposed across the gas. A self-coded computational fluid dynamics (CFD) program is used for the simulation of cold gas flow in order to evaluate the electrical field characteristic across open contacts and transient characteristics of insulations after small current interruption.

A Study on A Hot Gas Velocity Measurement in GCB Using Small-Gap (Small-Gap을 이용한 가스차단기에서의 열가스 속도측정에 관한 연구)

  • Kim, Hong-Kyu;Song, Ki-Dong;Park, Kyong-Yop;Hong, Jung-Pyo;Chong, Jin-Kyo
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.55 no.3
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    • pp.155-158
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    • 2006
  • $SF_6$ gas circuit breakers we widely used for short circuit current interruption in EHV or UHV power system. For a $SF_6$ gas circuit breaker development, the hot gas velocity measurement is necessary during $SF_6$ gas circuit breaker's trip operation. Small-gap flashover characteristics are used for this hot gas velocity measurement. This study sho was the hot gas velocity measurement results during $SF_6$ gas circuit breaker' trip operation.