• Title, Summary, Keyword: Short magnetic flux

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Analysis on Fault Current Limiting Characteristics of Flux-Lock Type SFCL Using Magnetic Flux Application Circuit (자기인가회로를 이용한 자속구속형 초전도한류기의 고장전류제한 특성 분석)

  • Go, Ju-Chan;Lim, Seung-Taek;Lim, Sung-Hun
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.30 no.1
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    • pp.37-41
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    • 2017
  • In this paper, the fault current limiting characteristics of the flux-lock type SFCL (superconducting fault current limiter) using magnetic application circuit were analyzed. The flux-lock type SFCL has the structure to install the magnetic application circuit, which can increase the resistance of HTSC ($high-T_C$ superconducting element comprising) the SFCL. To analyze the fault current limiting effect of the flux-lock type SFCL through the magnetic flux application circuit, the flux-lock type SFCL either with the magnetic flux circuit or without the magnetic flux circuit was constructed and the fault current limiting characteristics of the SFCL were compared each other through the short-circuit tests.

Influence of Flux Density of Electric Leakage Area by Inundation (침수에 의한 누전지역의 자속밀도 영향)

  • Choi, Woon-Shik;Kim, Tag-Yong;Kim, Jin-Sa
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.59 no.6
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    • pp.1109-1113
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    • 2010
  • Recently, important for the safety has been increasing together economic developments. The leakage only is measured by the voltage difference. This method is a way to contact the electric leakage area. It can cause electric shock at users. We propose a non-contact method to detect a short circuit in this paper. We investigate magnetic field at electric leakage area to present non-contact method. Simulated environment created a short circuit in the flooded areas. Voltage is supplied 50, 150 and 200[V]. Magnetic field was measured at 0, 5 and 10[cm]. Magnetic flux was reduced about $0.4[{\mu}T/cm]$ depending on the distance changes in the steady region. But we confirmed that magnetic flux is measured the same value depending on the distance changes in the electric leakage area.

Analysis on Air-Gap Magnetic Flux of Synchronous Generator According to Short-Circuit Types in Winding (권선단락 유형별 동기발전기의 공극자속 파형 분석)

  • Bae, Duck-Kweon;Kim, Dong-Hun;Park, Jung-Shin;Lee, Dong-Young;Lee, Sung-Ill
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.5
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    • pp.929-935
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    • 2009
  • As modem industrialized society progresses, the demand for electric power is increasing rapidly. The electric power system is getting amazingly bigger and complicated, which can easily induce serious troubles from the potential of large fault problems and/or system failure. The monitoring and diagnosis of the electric machine for the fault detection and protection has been important part in the electric power system. Most faults in the generator appear in the winding. This paper presents the air-gap magnetic flux characteristic of a small-scale 2-pole synchronous generator according to the faults in the field winding to protect the generator from the fault. The magnetic flux patterns in air-gap of a generator under various fault conditions as well as a normal state are simulated by using finite element method. These results are successfully applied to the detection and diagnosis of the short-circuit condition in rotor windings of a high capacitor generator.

Characteristics Analysis of Short Flux Path Switched Reluctance Motor

  • Ahn, Jin-Woo
    • Journal of international Conference on Electrical Machines and Systems
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    • v.1 no.2
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    • pp.38-45
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    • 2012
  • A novel kind of switched reluctance motor (SRM) with short flux path is proposed in this paper. Phase excitation in the SRM gives short flux paths, hence reducing the magnetomotive force required to drive the machine, resulting in significant reduction of copper wire and core losses compared to the typical SRM with diametric circulation of magnetic flux. To verify the performance, the characteristics analysis of a double-stator SRM, a 6/5 SRM with C-core structure, and a 4/5 two-phase SRM, which all have short flux paths, and a comparison with conventional SR motors are executed. The comparison demonstrates that the proposed motor offers some advantages in terms of torque and efficiency.

The Analysis of Current Limiting Performance in a High-$T_c$ Superconductor using Flux-Lock Concepts

  • 임성훈;최효상;김영순;이성룡;한병성
    • Progress in Superconductivity
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    • v.3 no.2
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    • pp.229-234
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    • 2002
  • In this paper, we analyzed the fault current performance in a $high-T_{c}$ superconductor(HTS) which was installed on flux-lock reactor with an external magnetic field coil covering the HTS. In this HTS fault current limiter using flux-lock concepts, the initial limiting current level can be controlled by adjusting the inductance of the coils. Furthermore, the current limiting characteristics of $high-T_{c}$ superconducting FCL can be improved by applying the external magnetic field into the $high-T_{c}$ superconductor. This paper discusses current limiting performance according to the inductance of the coil 1 in two cases with ac magnetic field coil or not and suggests the methods to improve the current limiting factor $P_{limit}$, which is defined as the ratio of the limited current $I_{FCL}$ at the current limiting phase to the prospective short -circuit current $I_{PSC}$.TEX> PSC/.

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Collisionless Magnetic Reconnection and Dynamo Processes in a Spatially Rotating Magnetic Field

  • Lee, Junggi;Choe, G.S.;Song, Inhyeok
    • The Bulletin of The Korean Astronomical Society
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    • v.41 no.1
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    • pp.45.1-45.1
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    • 2016
  • Spatially rotating magnetic fields have been observed in the solar wind and in the Earth's magnetopause as well as in reversed field pinch (RFP) devices. Such field configurations have a similarity with extended current layers having a spatially varying plasma pressure instead of the spatially varying guide field. It is thus expected that magnetic reconnection may take place in a rotating magnetic field no less than in an extended current layer. We have investigated the spontaneous evolution of a collisionless plasma system embedding a rotating magnetic field with a two-and-a-half-dimensional electromagnetic particle-in-cell (PIC) simulation. In magnetohydrodynamics, magnetic flux can be decreased by diffusion in O-lines. In kinetic physics, however, an asymmetry of the velocity distribution function can generate new magnetic flux near O- and X-lines, hence a dynamo effect. We have found that a magnetic-flux-reducing diffusion phase and a magnetic-flux-increasing dynamo phase are alternating with a certain period. The temperature of the system also varies with the same period, showing a similarity to sawtooth oscillations in tokamaks. We have shown that a modified theory of sawtooth oscillations can explain the periodic behavior observed in the simulation. A strong guide field distorts the current layer as was observed in laboratory experiments. This distortion is smoothed out as magnetic islands fade away by the O-line diffusion, but is soon strengthened by the growth of magnetic islands. These processes are all repeating with a fixed period. Our results suggest that a rotating magnetic field configuration continuously undergoes deformation and relaxation in a short time-scale although it might look rather steady in a long-term view.

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Design and Analysis of Switched Reluctance Motor with Short Flux Path (짧은 자속경로형 SRM의 설계와 특성해석)

  • Wang, Bo;Ahn, Jin-Woo
    • Proceedings of the KIPE Conference
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    • pp.81-82
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    • 2012
  • A novel kind of switched reluctance motor (SRM) with short flux path is proposed in this paper. Phase excitation in the SRM gives short flux paths, hence reducing the magnetomotive force required to drive the machine, resulting in significant reduction of copper wire and core losses compared to the typical SRM with diametric circulation of magnetic flux. To verify the performance, the characteristics analysis of a double stator SRM, a 6/5 SRM with C-core structure and a 4/5 two-phase SRM which all composed of short flux path and a comparison with conventional SR motors are executed.

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A Novel 6/5 Switched Reluctance Motor with Short Flux Path: Concept, Design and Analysis

  • Tanujaya, Marully;Lee, Dong-Hee;An, Young-Joo;Ahn, Jin-Woo
    • Journal of international Conference on Electrical Machines and Systems
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    • v.1 no.1
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    • pp.47-53
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    • 2012
  • A novel 6/5 switched reluctance motor (SRM) with short flux path is presented in this paper. The concept of this proposed motor is a novel SR motor with six stator and five rotor poles. The stator is constructed with three independent and physically separate C-core segments, and the rotor is composed of five poles. This motor, with a new selection for the number of stator/rotor poles, achieves a short flux path, which reduces the magnetomotive force required to drive the motor. To verify the performance of the proposed motor, a comparison with conventional SR motors with the same dimensions is executed. The comparison demonstrates that the proposed motor offers better performance in terms of maximum torque production. Furthermore, Finite Element Analysis (FEA) and Matlab/Simulink software are used to predict and simulate the performance of the proposed motor.

A Study on the Variation of Magnetic Field Intensity and Short Current by Coating Material of Spray in AF Track Circuits (AF궤도회로에서 코팅재에 의한 자계의 세기 및 단락전류 변화에 대한 연구)

  • Kim, Min-Seok;Oh, Sea-Hwa;Park, Yong-Gul;Lee, Jong-Woo
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.60 no.3
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    • pp.552-559
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    • 2011
  • There is a method for offering continuous information by AF track circuits. Magnetic fields are formed by current through rails in the AF track circuit systems. So, the continuous information is received by the magnetic fields on a on-board antenna. Coating materials of spray on rails are researched to decrease defects such as head check, shelling, corrugation, squats and so on in Germany. Currently, a coating method of rail construction is proposed by using the ceramics in Korea. When deciding physical characteristic of the coating material of spray, researches are required about variation of flux density and resistivity by using the coating material of spray. In case that the flux density is much lower than existing value, the information for train control is not transmitted to the on-board antenna. In this paper, inductance on rails is calculated and a model is presented about variation of the magnetic field intensity and resistivity in the AF track circuit. Standard permeability of the coating material of spray is proposed. Also, standard resistivity of the coating material of spray is presented by analyzing short current.