• Title/Summary/Keyword: AC magnetic field

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The AC loss of 22.9kV/50MVA High-Tc Superconducting Power Cable (22.9kV/50MVA급 고온초전도 전력케이블의 교류손실)

  • Choi, Suk-Jin;Lee, Sang-Jin;Sim, Ki-Deok;Cho, Jeon-Wook;Lee, Soo-Gil;Yang, Byeong-Mo;Yoon, Hyung-Hee
    • Progress in Superconductivity and Cryogenics
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    • v.11 no.3
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    • pp.31-34
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    • 2009
  • An HTS power cable is generally composed of 2 layers for conducting and 1 layer for shielding. For the analysis of AC loss of an HTS power cable, 2-dimensional magnetic field analysis is carried out. The magnetization loss in HTS cable core was calculated, and the transport current loss was obtained from the monoblock equation and the elliptical Norris Equation. And the total AC loss of the cable was expected by the sum of magnetization loss and transport current loss. The variation of ac loss with respect to the gap and uncertain factor between the superconducting tapes was investigated, and the ac loss of 22.9kV/50MVA high-Tc superconducting power cable was calculated. These results well agree with those of experiment.

Angular Dependency of Magnetization Losses in Continuously Transposed Coated Conductors for Large Current Applications (대전류용 초전도 연속전위도체의 외부자장 인가방향에 따른 자화손실 특성)

  • Han, B.W.;Kim, W.S.;Lee, J.K.;Lee, S.Y.;Park, S.H.;Kim, Y.I.;Choi, K.
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.59 no.1
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    • pp.51-56
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    • 2010
  • AC loss is main issue for power applications using YBCO coated conductor. The striated YBCO CC(Coated Conductor) has been proposed by several researchers to decrease a magnetization loss. A continuously transposed coated conductor (CTCC), suggested by our research group before, could be very useful for lower magnetization loss of large current power applications. In this paper, an AC loss reduction effect by the stack, striation and transposition of YBCO CCs under a time varying external magnetic field. To estimate the reduction effects for perpendicular magnetization loss, several CTCC samples were prepared and tested. Also, we measured angular dependency of magnetization losses of various CTCC samples.

Magnetic field Reduction characteristics of double shielding wear for a worker by using AC Arc welder (교류 아크용접기를 사용하는 작업자의 이중차폐복 자계저감 특성검토)

  • Park, Jun-Hyeong;Min, Suk-Won
    • Proceedings of the KIEE Conference
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    • 2008.10a
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    • pp.73-74
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    • 2008
  • This paper analyses current densities induced inside a worker using AC arc welder when he wear a protective with double shielding cloth. Applying the boundary element method, we calculate current densities induced in organs inside a worker in case he was located at 1[cm] far from a power cable of AC arc welder. As results of study, we fined aa protective cloth, which has high permeability in inner layer and high conductivity in outer layer, can give a higher shielding efficiency.

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Magnetic field Reduction characteristics of shielding wear for a worker by using AC Arc welder. (교류 아크용접기를 사용하는 작업자의 차폐복 자계저감 특성검토)

  • Park, Jun-Hyeong;Min, Suk-Won
    • Proceedings of the KIEE Conference
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    • 2008.07a
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    • pp.1343-1344
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    • 2008
  • This paper analyses current densities induced inside a worker using AC arc welder when he wears a protective cloth. Applying the boundary element method, we calculate current densities induced in organs inside a worker in case he was located at 1[cm], 15[cm], 20[cm] far from a power cable of AC arc welder. As results of study, we find a maximum current density induced in all organs may be lower than 10[$mA/cm^2$] if he wears a protective cloth. We also know high permeability materials can lower current density more than high conductivity materials.

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Development of Education System and Modeling (교육용 시스템 개발과 모형화)

  • Park, Seong-Wook;Lee, Deuk-Kee
    • Proceedings of the KIEE Conference
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    • 2001.07d
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    • pp.2042-2044
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    • 2001
  • The jumping ring apparatus of the type described in this study is used to demonstrate and educate the effects of electromagnetic induction. Placing an aluminum ring over the core and switching on AC source causes the ring to jump in the air due to induced currents in the ring producing a magnetic field opposed to that produced in the core. If the AC current is slowly increased from zero or ring is placed over the core when AC is already flowing the ring floats due to the balance between its weight and the upward electromagnetic force. Pentimum computer is used to display this value to screen and generate control signal.

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Speed measurement algorithm for low-resolution magnetic encoder of industrial electric vehicle (산업용 전기 차량의 저 분해능 마그네틱 엔코더를 사용한 속도 측정 방법)

  • Park, Gi-Hyoung;Jeong, Se-Jong
    • Proceedings of the KIPE Conference
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    • 2011.07a
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    • pp.312-313
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    • 2011
  • Recently, many industrial electric vehicles have been developed using various ac-motor drive technologies including field oriented vector control. Generally, a magnetic encoder is installed to have resistance to vibration and dust, and it is cost-effective. However, it is difficult to get an accurate rotor speed for high performance of vector control, because a resolution of the magnetic encoder is low and its phase accuracy is poor. In order to overcome this hardware problem, this study proposes a speed measurement algorithm using moving window for low-resolution magnetic encoder. This algorithm is experimentally tested and successfully applied to traction application of industrial electric vehicle.

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Speed measurement algorithm for low-resolution magnetic encoder of industrial electric vehicle (산업용 전기 차량의 저 분해능 마그네틱 엔코더를 사용한 속도 측정 방법)

  • Park, Gi-Hyoung;Jeong, Se-Jong
    • Proceedings of the KIPE Conference
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    • 2011.07a
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    • pp.316-317
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    • 2011
  • Recently, many industrial electric vehicles have been developed using various ac-motor drive technologies including field oriented vector control. Generally, a magnetic encoder is installed to have resistance to vibration and dust, and it is cost-effective. However, it is difficult to get an accurate rotor speed for high performance of vector control, because a resolution of the magnetic encoder is low and its phase accuracy is poor. In order to overcome this hardware problem, this study proposes a speed measurement algorithm using moving window for low-resolution magnetic encoder. This algorithm is experimentally tested and successfully applied to traction application of industrial electric vehicle.

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A survey on the EMF Levels of Study and Electric Appliances in Korea (국내 전철 및 가전제품을 대상으로 한 전자장 수준 실태조사)

  • Jang, Seong Ki;Cho, Yong Sung;Lee, Seok Jo;Yoo, Seong Wha;Jung, Kyung Mi;Lim, Jun Ho
    • Journal of Korean Society of Occupational and Environmental Hygiene
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    • v.15 no.1
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    • pp.71-81
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    • 2005
  • The purposes of this study was to collect, analyze, and describe the MF exposure levels from subways in Korea and to measure and evaluate the MF levels generated from electric appliances used at general homes. The target subway lines were Seoul Metropolitan Line 1 to Line 8, Bundang Line, Incheon Line, Daegu Line, Gwangju Line, and Busan Line 1 and Line 2. We measured at each station in those subway lines and, all the train types (pantograph-equipped, motor-equipped, and common), and platform types(facing and isolating) were investigated by the distance(80, 200, 400 cm) from the train on 19 targeted subway lines using 3 magnetic field measuring devices (EMDEXII, Enertech Co.) during the survey from January till October, 2004. On the other hand, the levels of the 60Hz magnetic fields generated from 14 items of home electric appliances such as electric blankets, hair dryers, electric razors, etc. were measured at 10 general homes using 5 EMDEXII meters with a sampling interval of 1.5 second by the distance(surface, 30, 50, 100, 300cm ) from the target electric appliances. The survey results in the whole subway lines examined in this study were as follows; Seoul Metropolitan Line 4 using AC(alternating current) power source showed the highest mean value of $2.85{\mu}T$, followed by Seoul Metropolitan Line 1 running between Seoul and Incheon using AC($2.78{\mu}T$), Seoul Metropolitan Line 1 between Seoul and Uijongbu using AC($2.73{\mu}T$), Bundang Line using AC($1.79{\mu}T$), Seoul Metropolitan Line 1 connected from Yongsan using AC($1.67{\mu}T$), Seoul Metropolitan Line 1 between Seoul and Suwon using AC($0.79{\mu}T$), and so on. In general, the intensity of the magnetic field in the subway systems in Korea was significantly higher when using AC($2.14{\pm}0.91{\mu}T$) than when using DC($0.29{\pm}0.44{\mu}T$) power source. Among the home electric appliances examined, microwave ovens showed the highest mean value of $7.69{\mu}T$, followed by hair dryers($6.47{\mu}T$), vacuum cleaners($5.27{\mu}T$), televisions ($2.26{\mu}T$), electric blankets($1.38{\mu}T$), personal computers ($0.81{\mu}T$), and so on. Two items of electric appliances showed the excess value of $0.2{\mu}T$ at the distance of 30cm in the MF exposure level; electric razors $1.58{\pm}2.13{\mu}T$ and vacuum cleaners $0.48{\pm}0.44{\mu}T$. As a whole, this study showed a tendency that the shift of the MF levels according to the increase of distance from the electric appliances was lower than those of the results surveyed in UK and USA. As a result, this study is expected to suggest meaningful data for the future study in exposure assessment of magnetic fields and for the establishment of guidelines for subways and electric appliances in Korea. More detailed and large scaled exposure assessment studies should be performed continuously to get the various and useful information on health risk assessment of MFs in Korea.

Detection Property of Red Blood Cell-Magnetic Beads Using Micro Coil-Channeland GMR-SV Device (마이크로 코일-채널과 GMR-SV 소자를 이용한 적혈구-자성비드 검출 특성연구)

  • Park, Ji-Soo;Kim, Nu-Ri;Jung, Hyun-Jun;Lee, Sang-Suk
    • Journal of the Korean Magnetics Society
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    • v.25 no.1
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    • pp.16-21
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    • 2015
  • The micro device, coil, and channel for the biosensor integrated with the GMR-SV device based on the antiferromagnetic IrMn layer was fabricated by the light lithography process. When RBCs coupled with several magnetic beads with a diameter of $1{\mu}m$ passed on the micro channel, the movement of $RBC+{\mu}Beads$ is controlled by the electrical AC input signal. The $RBC+{\mu}Beads$ having a micro-magnetic field captured above the GMR-SV device is changed as the output signals for detection status. From these results, the GMR-SV device having the width magnitude of a few micron size can be applied as the biosensor for the analysis of a new magnetic property as the membrane's deformation of RBC coupled to magnetic beads.

Transport Loss Characteristic of the Bifilar Pancake Type Fault Current Limiting Coil using Coated Conductor (Coated Conductor를 사용한 무유도 팬케이크형 한류 코일의 통전 손실 특성)

  • Park, Dong-Keun;Bang, Joo-Seok;Yang, Seong-Eun;Ahn, Min-Cheol;Sim, Ki-Deok;Yoon, Yong-Soo;Nam, Kwan-Woo;Seok, Bok-Yeol;Ko, Tae-Kuk
    • Progress in Superconductivity and Cryogenics
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    • v.9 no.3
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    • pp.21-25
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    • 2007
  • Superconducting fault current limiter (SFCL) is attractive apparatus to reduce fault current in power grid. Since it is applied to the alternating current (AC) power line, the SFCL has losses in the normal operation. Recently, coated conductor (CC) is noticeable material employed for resistive bifilar winding type SFCL in many research groups. Bifilar structure is expected to have low AC loss by magnetic field offset as compared with the single tape structure in the same length. This paper reports about characteristic of bifilar pancake type coil for SFCL application in AC loss aspect. The bifilar coil is wound using CC with facing on HTS sides each other. Transport AC loss measurement and characteristic analysis of the bifilar coil using CC have been performed at 77K. The test results are compared with the Norris equations and the test results of non-inductively wound paralleled solenoid type coil which is suggested and tested in this group at present.