• Title, Summary, Keyword: Transient phenomena

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A Study on Power Cable Fault Using PSCAD/EMTDC (PSCAD/EMTDC를 이용한 전력케이블 고장현상에 판한 연구)

  • Kim, Jeom-Sik;Lee, Jong-Beom
    • Proceedings of the KIEE Conference
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    • pp.868-870
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    • 1996
  • This paper describes the faun phenomena by the simulation in power system including underground transmission power cable. Studying on fault phenomena is a very important part to decide the circuit breaker, protective relay and system configuration. Simulation was carried out in several different model system depended upon cable kinds using PSCAD/EMTDC, which is one of the transient program. The simulated results show the possibility to analyze transient phenomena for the cable system.

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Study on the Transient Characteristics of the Sensor Tube of a Thermal Mass Flow Meter (열식 질량 유량계 센서관의 과도 특성에 관한 연구)

  • Kim, Dong-Kwon;Han, Il-Young;Kim, Sung-Jin
    • Proceedings of the KSME Conference
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    • pp.308-313
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    • 2003
  • Thermal mass flow meters (TMFMs) are most widely used for measuring mass flow rates in the semiconductor industry. A TMFM should have a short response time in order to measure the time-varying flow rate rapidly and accurately. Therefore it is important to study transient heat transfer phenomena in the sensor tube of a TMFM that is the most critical part in the TMFM. In the present work, a simple numerical model for transient heat transfer phenomena of the sensor tube of a TMFM is presented. Numerical solutions for the tube and fluid temperatures in a transient state are obtained using the proposed model and compared with experimental results to validate the proposed model. Based on numerical solutions, heat transfer mechanism in a transient state in the sensor tube is explained. Finally, a correlation for predicting the response time of a sensor tube is presented. The correlation is verified by experimental results.

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Analysis of the torque transient performance of the induction motor by means of phase segregation method (상분리법에 의한 유도전동기의 토오크 과도특성해석)

  • Jeong, Jong-Ho;Lee, Eun-Woong;Choi, Jae-Young
    • Proceedings of the KIEE Conference
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    • pp.247-249
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    • 2000
  • Transient phenomena cause delay in control response and must be studied and eliminated, if possible, suppressed. The difficulty in analyzing transient phenomena in ac machines comes from the large number of windings involved. But, it is possible that only one phase is used to represent three phases of the induction motor as called phase segregation method. The phase segregation method provides equivalent circuits for both the steady and transient states of induction motor. In this paper, analysis of the torque transient of the induction motor be carried out the phase segregation method and confirmed in the possibility of transientless torque control.

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A FLUID TRANSIENT ANALYSIS FOR THE PROPELLANT FLOW IN A MONOPROPELLANT PROPULSION SYSTEM (단일추진제 추진시스템의 과도기유체 해석)

  • Chae, Jong-Won
    • Journal of computational fluids engineering
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    • v.10 no.2
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    • pp.69-81
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    • 2005
  • A fluid transient analysis for the propellant flow in a monopropellant propulsion system is conducted by using the method of characteristics(MOC). It reviews algebraic simultaneous equations method and Cramer's rule method utilized to drive the compatible and characteristic equations to understand MOC extensively. The identification of fluid transient phenomena of propulsion system of Koreasat 1 is carried out through parametric studies. The valve response time is one of the dominant parameters governing the fluid transient phenomena. The results show that the shorter closing time induces the greater pressure response amplitude. And it shows that the installation of in-line orifice is effectively to limit the fluid transients in rapid valve response time and at high pressure. But it seems that the effect of orifice weakens at slow valve response time and at low pressures.

Boiling CHF phenomena in water and FC-72

  • Park, Jongdoc;Fukuda, Katsuya;Liu, Qiusheng
    • Journal of Advanced Marine Engineering and Technology
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    • v.38 no.5
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    • pp.581-588
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    • 2014
  • Extensive researches toward pool boiling characteristics have been widely investigated. However, the correct understanding of its boiling crisis by Critical Heat Flux (CHF) phenomenon during steady and transient heat transfer as a fundamental database for designing heat generation systems is still need to be clarified. The pool boiling CHFs were investigated to clarify the generalized phenomena of transition to film boiling at transient condition. The CHFs were measured on 1.0 mm diameter horizontal cylinder of platinum for exponential heat generation rates with various periods for saturated liquids at atmospheric pressure. The incipience of boiling processes was completely different depending on pre-pressurization. Also, the dependence of pre-pressure in transient CHFs changed due to the wettability of boiling liquids. The trend of typical CHFs were clearly divided into the first, second and third groups for long, short and intermediate periods, respectively. By the effect of pre-pressurization, the boiling incipience mechanism was replaced from that by active cavities entraining vapor to that by the HSN in originally flooded cavies.

Transient Phenomena Analysis and Estimation According to Unbalance Factors on Underground Power Cable Systems (지중송전계통에서 불평형 구성요소에 따른 과도현상 해석 및 평가)

  • Jung Chae-Kyun;Lee Jong-Beom;Kang Ji-Won;Lee Dong-Il
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.54 no.8
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    • pp.410-417
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    • 2005
  • This paper analyses the transient phenomena against single line to ground fault and lightning surge on underground power cable systems. For analysis in various fault conditions, several actual underground power cable systems are modeled using ATP In ground fault, the transient characteristic of the conductor and the sheath according to the fault current and the installation types of CCPU are analysed. In lightning surge strokes, the various unbalanced conditions including the length of crossbonded lead, the breakdown of CCPU and distance unbalance are considered. This paper is expected to contribute the establishment of proper protection methods against transients on underground power cable systems.

Investigation of Corrosion Fatigue Phenomena in Transient Zone and Preventive Coating and Blade Design against Fouling and Corrosive Environment for Mechanical Drive Turbines

  • Hata, Satoshi;Nagai, Naoyuki;Yasui, Toyoaki;Tsukamoto, Hiroshi
    • International Journal of Fluid Machinery and Systems
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    • v.1 no.1
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    • pp.121-139
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    • 2008
  • For mechanical drive steam turbines, the investigation results of corrosion fatigue phenomena in the transient zone are introduced, including basic phenomena on expansion line and actual design and damage experience. These results were analyzed from the standpoint of stress intensity during the start of cracking. In order to resolve such problems, preventive coating and blade design methods against fouling and corrosive environments are developed. Detailed evaluation test results are given for coating performance using a unique test procedure simulating fouling phenomena and washing conditions. Finally, the results of the successful modification of internals and on-line washing results on site are introduced.

Simulation of Submicron MOSFET Using Hydrodynamic Model (Hydrodynamic model을 이용한 Submicron MOSFET의 Simulation)

  • 김충원;한백형;김경석
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.30A no.11
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    • pp.122-131
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    • 1993
  • In this paper, we have developed a submicron Si MOSFET simulator, which is physically based on the hydrodynamic energy transport mode. The simulator was used to investigate the nonstationary transport effects and the transient phenomena in submicron Si MOSFET's. It is found that the velocity overshoot and the carrier heating are dominant transport mechanism near the drain end of the channel and the transient phenomena is more retained in a long channel MOSFET.

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Modeling and Fault Simulation of Hydro Generator Control System (수력 발전기 제어설비의 모델링과 사고 시뮬레이션)

  • Park, Chul-Won
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.29 no.4
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    • pp.102-107
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    • 2015
  • In this paper, the generator control system by using PSCAD/EMTDC was modeled and several faults simulation were performed. The generator control system is composed of generator, turbine, exciter and governor. The parameters of generator control system model were obtained from field power plant. And then, the various transient phenomena through obtained several signal of developed modeling were analyzed.

The Protection methods of Telecommunication Network from Electrical Transient Phenomena (전기적 과도현상으로부터 통신망의 보호대책)

  • Choi, Man-Ho;Kim, Hyun-Duk;Kim, Byung-Cheul
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • v.9 no.2
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    • pp.693-696
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    • 2005
  • Parallel and cross of the electrical power and telecommunication network is become accelerated, because telecommunication equipments are constructed according to road for efficient maintenance of domestic telecommunication network. The electrical power network can generate an electrostatic induction, and is itself transmission medium from electrical transient phenomenon such as lighting. So, transient phenomenon of lightning surge is induced to telecommunication network, and then it is damaged by connecting between electrical ground of electrical power network and telecommunication network. In this study, we found that cut-off of return path current by separate distance between electrical ground of electrical power network and telecommunication network, and cut-off of electrostatic induction voltage by grounding unused leads of both terminals of the electrical and telecommunication network have good effect as the protection methods of telecommunications network from electrical transient phenomena.

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