• Title/Summary/Keyword: magnetic switch

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Characteristics of the magnetic flux-offset type FCL by switching component

  • Jung, Byung-Ik;Choi, Hyo-Sang
    • Progress in Superconductivity and Cryogenics
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    • v.18 no.2
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    • pp.18-20
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    • 2016
  • The study of superconducting fault current limiter (SFCL) is continuously being studied as a countermeasure for reducing fault-current in the power system. When the fault occurred in the power system, the fault-current was limited by the generated impedance of SFCLs. The operational characteristics of the flux-offset type SFCL according to turn ratios between the primary and the secondary winding of a reactor were compared in this study. We connected the secondary core to a superconductor and a SCR switch in series in the suggested structure. The fault current in the primary and the secondary winding of the reactor and the voltage of the superconductor on the secondary were measured and compared. The results showed that the fault current in the load line was the lowest and the voltage applied at both ends of the superconductor was also low when the secondary winding of the reactor had lower turn ratio than the primary. It was confirmed based on these results that the turn ratio of the secondary winding of the reactor must be designed to be lower than that of the primary winding to reduce the burden of the superconductor and to lower the fault current. Also, the suggested structure could increase the duration of the limited current by limiting the continuous current after the first half cycle from the fault with the fault current limiter.

Development of Seismic Monitoring Analysis System for HANARO (하나로 지진감시 분석시스템 개발)

  • 류정수;김형규;윤두병
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2002.10a
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    • pp.330-337
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    • 2002
  • The HANARO seismic monitoring system is classified as non-nuclear safety(NNS), seismic category I, and quality class T The seismic monitoring system installed at the instrument room consists of five field sensors and one monitoring cabinet. The field sensors are composed of three triaxial accelerometers which installed at base slab, free field and overhead crane support respectively, a seismic trigger and a seismic switch at base slab. The most parts of analog system except field sensors are not produced any more, the improvement of the system is to be needed. The analog system with magnetic tape recorder is not only out-of-date model but dependent upon foreign technology. So it is difficult to get the spare parts and the cost to buy them is increased. Therefore we have improved the analog seismic monitoring system into a new digital seismic monitoring analysis system(SMAS) except five field sensors. After the installation of the new SMAS, we have carried out the site acceptance test(SAT) to confirm the field functions. The results of SAT satisfy the requirements of the fabrication technical specification. This new SMAS is operating at HANARO instrument room to acquire and analyse the signal of earthquake.

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The Study on the Mutual Characteristics Between Transmitting Efficiency of Pulse Energy and Wall Plug Consumed Power of Non-Thermal Plasma (저온 플라즈마의 펄스에너지 전송효율과 Wall Plug 소비전력과의 상호 특성에 관한 연구)

  • Jeong, Jong-Han;Jeong, Hyeon-Ju;Kim, Hwi-Yeong;Jeong, Yong-Ho;Song, Geum-Yeong;Kim, Geun-Yong;Kim, Hui-Je
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.51 no.10
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    • pp.506-510
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    • 2002
  • In this paper, we study on the mutual characteristics between transmitting efficiency of pulse energy and wall plug consumed power of non-thermal Plasma for removing environmental pollutive gas of coal plant. To obtain high pulse energy of our system, we used MPC(magnetic pulse compressor) of power switch and tested their characteristics by adjusting electrode length of reactor and charging voltage in capacitor. As a result, we obtained consumed power of wall plug and a compressed pulse of voltage 110kV, rising time 500ns. Impedance of load on increasing electrode length was decreased, but electrical efficiency was increased. These results indicate we can control critical voltage of pulse corona and electrical efficiency of economic cost in power plant.

Study on the Reduction of Vibration, Acoustic Noise of SRM by DC Excitation Commutation Method (SRM의 직류여자 전류방식에 의한 진동, 소음의 저감 대책에 관한 연구)

  • Hwang, Yeong-Mun;Jeong, Tae-Uk;O, Seong-Gyu;Chu, Yeong-Bae
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.49 no.1
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    • pp.1-8
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    • 2000
  • Switched reluctance motor(SRM) has simple magnetic structure, and requires simple power electronic driving circuit. It is very useful for wide range adjustable speed drive system. But, SRM drive generates large vibration and acoustic noise because it is commutated individually by step pulse m.m.f of each phase pole. In the vibration and acoustic noise characteristics. The considerable vibration and noise is induced by radial deforming of stator, so the frequency of dominant vibration and noise is coincident with the frequency of natural mode frequency of mechanical structure. This radial vibration force is generated in the phase commutation region. This paper suggests the new electromagnetic structure of SRM with auxiliary commutation winding which is excited by direct current. This phase and commutation winding are coupled magnetically between one phase winding and the other. Therefore, the switch-off phase current is absorbed by the another phase winding. By this interaction of phase and commutation winding in commutation mechanism, vibration and noise is reduced. And this reduction effect is examined by the test of prototype machine. As a result, SRM with DC exciting commutation winding is very useful to reduce vibration and acoustic noise.

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A Study on the Electro-magnetic Wave of Inductive Power Transfer System for Light Railway Transit (경량전철용 유도급전 시스템의 전자파 분석 연구)

  • Park, Chan-Bae;Lee, Byung-Song;Lee, Hyung-Woo
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.61 no.8
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    • pp.1210-1215
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    • 2012
  • Traction motors for driving and power conversion devices using semiconductor switch are equipped with a transportation systems such as an electrical railway system. Power conversion devices have the possibility of malfunction by external electromagnetic waves. As a result, these could affect the safe operation of the railway. Moreover, the electromagnetic waves above safe limits will be harmful to the passengers inside the railway vehicles or anyone working around the rail-track. For this reason, the importance and need about the reliability check and complement of electromagnetic waves generated from the IPT(Inductive Power Transfer) system have been suggested for the safe application of the IPT system to the railway system. In this study, prediction for the electromagnetic wave properties was conducted through FEM(Finite Element Method) analysis of 5kW-class IPT system design model. Next, the 5kW IPT system prototype was made and then the small-scaled railway vehicle was made to mount the IPT system and the energy management system. Finally, the electromagnetic waves generated from the real small-scaled IPT system were measured and analyzed, and then the reliability check of predictions by FEM analysis were carried out.

Resolution of Protein-Losing Enteropathy after Congenital Heart Disease Repair by Selective Lymphatic Embolization

  • Kylat, Ranjit I;Witte, Marlys H;Barber, Brent J;Dori, Yoav;Ghishan, Fayez K
    • Pediatric Gastroenterology, Hepatology & Nutrition
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    • v.22 no.6
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    • pp.594-600
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    • 2019
  • With improving survival of children with complex congenital heart disease (CCHD), postoperative complications, like protein-losing enteropathy (PLE) are increasingly encountered. A 3-year-old girl with surgically corrected CCHD (ventricular inversion/L-transposition of the great arteries, ventricular septal defect, pulmonary atresia, postdouble switch procedure [Rastelli and Glenn]) developed chylothoraces. She was treated with pleurodesis, thoracic duct ligation and subsequently developed chylous ascites and PLE (serum albumin ${\leq}0.9g/dL$) and was malnourished, despite nutritional rehabilitation. Lymphangioscintigraphy/single-photon emission computed tomography showed lymphatic obstruction at the cisterna chyli level. A segmental chyle leak and chylous lymphangiectasia were confirmed by gastrointestinal endoscopy, magnetic resonance (MR) enterography, and MR lymphangiography. Selective glue embolization of leaking intestinal lymphatic trunks led to prompt reversal of PLE. Serum albumin level and weight gain markedly improved and have been maintained for over 3 years. Selective interventional embolization reversed this devastating lymphatic complication of surgically corrected CCHD.

Research on Impact Sensors for Developing the Electronic Body Protector of Taekwondo (태권도 전자호구 개발을 위한 충격감지 센서 연구)

  • Ki, Jae-Sug;Jeong, Dong-Hwa;Lee, Hyun-Jun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.4
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    • pp.648-655
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    • 2019
  • This paper proposes the differential development of a Taekwondo electronic body protector. For this development, the most suitable sensor system was selected after analyzing and testing various sensor methods (magnetic sensors, electric capacity sensors, contact switch sensors, and piezo-film sensors) that could be applied in the electronic body protector, the selected sensors were distributed to the body and feet to make a more precise hit score, unlike the existing system in which all sensors are centralized on the body. Furthermore, it aims to illuminate using a lightweight film-type piezoelectric sensor on the body protector. In the case of an existing electronic body protector, all sensors and network device were concentrated on the body protector, so users need to purchase a set if they want it. On the other hand, the proposed system cloud can be used individually using a smart scoring WEP program. The effects of decreasing weight by up to 20% were compared with those of the existing system. Setting up a test facility is very difficult, so more study will be needed to analyze the effects of a hit.

A Contactless Power Supply for a DC Power Service

  • Kim, Eun-Soo;Kim, Yoon-Ho
    • Journal of international Conference on Electrical Machines and Systems
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    • v.1 no.4
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    • pp.483-491
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    • 2012
  • It is expected that, in the future, DC power service will be widely used for photovoltaic home power generation systems, since DC consuming devices are ever increasing. Instead of using multiple converters to convert DC to AC and then AC to DC, the power service could solely be based on DC. This would eliminate the need for converters, reducing the cost, complexity, and possibly increasing the efficiency. However, configuration of direct DC power service with mechanical contacts can cause spark voltage or an electric shock when the switch is turned on and off. To solve these problems, in this paper, a contactless power supply for a DC power service that can transfer electric power produced by photovoltaics to the home electric system using magnetic coupling instead of mechanical contacts has been proposed. The proposed system consists of a ZVS boost converter, a half-bridge LLC resonant converter, and a contactless transformer. This proposed contactless system eliminates the use of DC switches. To reduce the stress and loss of the boost converter switching devices, a lossless snubber with coupled inductor is applied. In this paper, a switching frequency control technique using the contactless voltage sensing circuit is also proposed and implemented for the output voltage control instead of using additional power regulators. Finally, a prototype consisted of 150W boost converter has been designed and built to demonstrate the feasibility of the proposed contactless photovoltaic DC power service. Experimental results show that 74~83% overall system efficiency is obtained for the 10W~80W load.

A CONSTRUCTION OF AN AUTOMATIC OBSERVATION SYSTEM FOR BRIGHT AND LONG PERIOD VARIABLE STARS (밝은 장주기 변광성관측을 위한 자동관측시스템 구축)

  • Yoon Joh-Na;Lee Chung-Uk;Cha Sang-Mok;Kim Yong-Gi
    • Journal of Astronomy and Space Sciences
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    • v.23 no.2
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    • pp.143-152
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    • 2006
  • An automatic observation system has been constructed at Chungbuk National University for the purpose of monitoring the bright and long period variable stars effectively. We improved the control part of 40cm telescope of the LX200 and developed n observing software ObsTool II so that the telescope, CCD camera and dome can be controlled in one software. ObsTool II is a COM (Common Object Module) based software, which can be easily reprogrammed in case that a new telescope or CCD camera is installed. Because this system has an additional function in which the telescope can switch the variable, comparison, and check stars respectively as like a photoelectric observation, we can observe the variable star even if the CCD view field does not contain the comparison star with the variable star. In order to check the system stability a W UMa type variable V523 Cas and a magnetic cataclysmic variable TT Ari have been observed with the constructed system and the results have been discussed in context with the possibility of a further application of our automatical observation system.

A New Photovoltaic System Architecture of Module-Integrated Converter with a Single-sourced Asymmetric Multilevel Inverter Using a Cost-effective Single-ended Pre-regulator

  • Manoharan, Mohana Sundar;Ahmed, Ashraf;Park, Joung-Hu
    • Journal of Power Electronics
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    • v.17 no.1
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    • pp.222-231
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    • 2017
  • In this paper, a new architecture for a cost-effective power conditioning systems (PCS) using a single-sourced asymmetric cascaded H-bridge multilevel inverter (MLI) for photovoltaic (PV) applications is proposed. The asymmetric MLI topology has a reduced number of parts compared to the symmetrical type for the same number of voltage level. However, the modulation index threshold related to the drop in the number of levels of the inverter output is higher than that of the symmetrical MLI. This problem results in a modulation index limitation which is relatively higher than that of the symmetrical MLI. Hence, an extra voltage pre-regulator becomes a necessary component in the PCS under a wide operating bias variation. In addition to pre-stage voltage regulation for the constant MLI dc-links, another auxiliary pre-regulator should provide isolation and voltage balance among the multiple H-bridge cells in the asymmetrical MLI as well as the symmetrical ones. The proposed PCS uses a single-ended DC-DC converter topology with a coupled inductor and charge-pump circuit to satisfy all of the aforementioned requirements. Since the proposed integrated-type voltage pre-regulator circuit uses only a single MOSFET switch and a single magnetic component, the size and cost of the PCS is an optimal trade-off. In addition, the voltage balance between the separate H-bridge cells is automatically maintained by the number of turns in the coupled inductor transformer regardless of the duty cycle, which eliminates the need for an extra voltage regulator for the auxiliary H-bridge in MLIs. The voltage balance is also maintained under the discontinuous conduction mode (DCM). Thus, the PCS is also operational during light load conditions. The proposed architecture can apply the module-integrated converter (MIC) concept to perform distributed MPPT. The proposed architecture is analyzed and verified for a 7-level asymmetric MLI, using simulation results and a hardware implementation.