• Title/Summary/Keyword: Magnetization Loss

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A Study on the Small Isolator Characteristics and Design of Mobile Phones (이동통신 단말기용 소형 아이솔레이터 특성 및 설계에 관한 연구)

  • 이영훈;권원현
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.12 no.2
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    • pp.165-175
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    • 2001
  • In this paper, it is analyzed lumped element isolators analytically by the analysis program using scattering matrixes including ferrite saturation magnetization, external direct current magnetic field and strip line length and width, designed and experimented the small isolator of mobile phone. The simulation results show that the characteristics of the isolator are affected by external R, C, length and width of strip line and ferrite width and saturation magnetization sensitivity. We proposed the isolator specification applied cellular and PCS mobile phones, experimented the isolator for cellular mobile phones. From the experimented result, isolation and return loss are measured below 20 dB, insertion loss is below 0.7 dB, bandwidth is about 44 MHz at center frequency 836.5 KHz. The implemented isolator has better performances than the conventional one.

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Fabrication and Magnetic Process of 13Cr-1.5Nb-Fe Stainless Sensors (13Cr-1.5Nb-Fe 스텐레스 센서재료의 제조 및 연자기특성)

  • 윤성호;김택기;조용수
    • Journal of the Korean Magnetics Society
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    • v.8 no.3
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    • pp.125-130
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    • 1998
  • 13Cr-1.5Nb-Fe alloy powder was fabricated by water atomization method, and ring-shape specimen of this composition was fabricated by oil press, and then sintered in the vacuum furnace. Powder shape, size distribution, composition (C, N, O, S) analysis and saturation magnetization of as-prepared 13Cr-1.5Nb-Fe alloy powder were investigated. Ac permeability and power loss was measured after forming and sintering process. Saturation magnetization and contents of oxygen of the alloy powder is160 emu/g and about 6000 ppm, respectively. 50 % volume fraction indicate particle size of 70$\mu$m. The ac permeability of sintered specimen increases with increasing sintering temperature and forming pressure. The power loss is 107 W/cc at sintering temperature of 1200 $^{\circ}C$, 12 ton/$\textrm{cm}^2$ forming pressure, and 20 KHz. It is the lowest among the prepared specimen.

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Modified Current Differential Relay for $Y-{\Delta}$ Transformer Protection ($Y-{\Delta}$ 변압기 보호용 수정 전류차동 계전기)

  • Jin, En-Shu;Kang, Yong-Cheol
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.55 no.3
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    • pp.95-101
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    • 2006
  • This paper proposes a modified current differential relay for $Y-{\Delta}$ transformer protection. The relay uses the same restraining current as a conventional relay, but the differential current is modified to compensate for the effects of the exciting current. A method to estimate the circulating component of the delta winding current is proposed. To cope with the remanent flux, before saturation, the core-loss current is calculated and used to modify the measured differential current. When the core then enters saturation, the initial value of the flux is obtained by inserting the modified differential current at the start of saturation into the magnetization cure. Thereafter, the core flux is then derived and used in conjunction with the magnetization curve to calculate the magnetizing current. A modified differential current is then derived that compensates for the core-loss and magnetizing currents. The performance of the proposed differential relay was compared against a conventional differential relay. Test results indicate that the modified relay remained stable during severe magnetic inrush and over-excitation, because the exciting current was successfully compensated. This paper concludes by implementing the relay on a hardware platform based on a digital signal processor. The relay does not require additional restraining signal and thus cause time delay of the relay.

Modified Current Differential Relay for Y-$\Delta$ Transformer Protection (Y-$\Delta$ 변압기 보호용 수정 전류차동 계전기)

  • Kang, Yong-Cheol;Jin, En-Shu;Lee, Byung-Eun
    • Proceedings of the KIEE Conference
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    • 2004.11b
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    • pp.9-13
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    • 2004
  • This paper proposes a modified current differential relay for Y-$\Delta$ transformer protection. The relay uses the same restraining current as a conventional relay, but the differential current is modified to compensate for the effects of the exciting current. A method to estimate the circulating component of the delta winding current is proposed. To cope with the remanent flux, before saturation, the core-loss current is calculated and used to modify the measured differential current. When the core then enters saturation, the initial value of the flux is obtained by inserting the modified differential current at the start of saturation into the magnetization cure. Thereafter, the core flux is then derived and used in conjunction with the magnetization curve to calculate the magnetizing current. A modified differential current is then derived that compensates for the core-loss and magnetizing currents. The performance of the proposed differential relay was compared against a conventional differential relay. Test results indicate that the modified relay remained stable during severe magnetic inrush and over-excitation because the exciting current was successfully compensated. The relay correctly discriminates magnetic inrush and over-excitation from an internal fault and is not affected by the level of remanent flux.

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High-frequency Magnetic Properties of Ni-Zn-Co Ferrites Used for Mangetic Shielding in NFC (NFC의 자기 차폐용 Ni-Zn-Co 페라이트 자성체의 고주파 자기특성)

  • Ryu, Yo-Han;Kim, Sung-Soo
    • Journal of Powder Materials
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    • v.21 no.6
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    • pp.429-433
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    • 2014
  • This study investigated the magnetic properties and frequency dispersion of complex permeability of Ni-Zn-Co ferrites used for magnetic shielding in near field communication (NFC) system. The sintered specimens of $(Ni_{0.7}Zn_{0.3})_{1-x}Co_xFe_2O_4$ composition were prepared by the conventional ceramic processing. The coercive force and saturation magnetization were measured by vibrating sample magnetometer. The complex permeability was measured by RF impedance analyzer in the range of 1 MHz~1.8 GHz. The coercive force increased and saturation magnetization decreased with increasing the Co substitution. The real and imaginary parts of complex permeability decreased and the resonance frequency increased with Co substitution, which was attributed to the increase in crystal anisotropy field and reduction in saturation magnetization. The effect of Co substitution could be found in reducing the magnetic loss to nearly zero at the operating frequency of NFC (13.56 MHz).

The Influence of Magnetic Field Orientating on Magnetization Loss of a Bi-2223 Tape (자장 방향이 Bi-2223테이프의 자화손실에 미치는 영향)

  • 한형주;김현준;류경우;최병주;최세용;나완수
    • Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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    • 2002.02a
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    • pp.271-273
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    • 2002
  • The ac loss in Bi-2223 tapes has been studied by a magnetic method. A brief overview of the theoretical background and the experimental set-up is presented. Measurements are made at 77 K in a magnetic fields. The magnitude of the ac loss indicates that filaments are fully coupled, which agrees with theory. As in other measurements, the loss in perpendicular field is larger than that in the parallel field by about a factor 10, which is close to the aspect ratio of the tape.

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A Modified Current Differential Relay for Transformer Protection (변압기 보호용 수정 전류차동 계전방식)

  • 강용철;김은수;원성호
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.53 no.2
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    • pp.80-86
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    • 2004
  • During magnetic inrush or over-excitation, saturation of the core in a transformer draws a large exciting current, which can cause mal-operation of a differential relay. This paper proposes a modified current differential relay for transformer protection. The relay calculates core-loss current from the induced voltage and the core-loss resistance; the relay calculates the magnetizing current from the core flux and the magnetization curve. Finally, the relay obtains the modified differential current by subtracting the core-loss and the magnetizing currents from the conventional differential current. Comparison study with the conventional differential relay with harmonic blocking is also shown. The proposed technique not only discriminates magnetic inrush and over-excitation from an internal fault, but also improves the speed of the conventional relay.

Hysteresis loss of YBCO thin film strip with filamentary structure (필라멘트 구조의 YBCO 박막의 자기이력 손실)

  • Park H. W;Na D. H;Kim M. J;Chang Y. S;Kim J. M;Ri H.-C;Lee Y. H
    • Progress in Superconductivity
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    • v.6 no.2
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    • pp.99-103
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    • 2005
  • For ac applications a detailed understanding of the ac power losses associated with different conductor configurations is of crucial importance. YBCO thin films were divided into parallel filaments with widths of 1, 2, and 4 mm to reduce hysteresis losses. The measured hysteresis losses show a linear relationship between the strip width and hysteresis loss as anticipated. The influence of different inter-filament separations on the hysteresis loss is investigated.

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Modified-Current-Differential Relay for Transformer Protection

  • Kang Yong-Cheol;Jin En-Shu;Won Sung-Ho
    • KIEE International Transactions on Power Engineering
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    • v.5A no.1
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    • pp.1-8
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    • 2005
  • During magnetic inrush or over-excitation, saturation of the core in a transformer draws a significant exciting current, which can cause malfunction of a current-differential relay. This paper proposes a modified-current-differential relay for transformer protection. The relay calculates the core-loss current from the induced voltage and the core-loss resistance as well as the magnetizing current from the core flux and the magnetization curve. Finally, the relay obtains the modified differential current by subtracting the core-loss and the magnetizing currents from the conventional differential current. A comparative study of the conventional differential relay with harmonic blocking is presented. The proposed relay not only discriminates magnetic inrush and over-excitation from an internal fault, but also improves the relay speed.

Simplified Modeling of Ring Resonators and Split Ring Resonators Using Magnetization

  • Jeon, Dongho;Lee, Bomson
    • Journal of electromagnetic engineering and science
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    • v.13 no.2
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    • pp.134-136
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    • 2013
  • This paper examines various aspects of the electromagnetic responses of the ring resonator located in the transverse electromagnetic cell. In addition, an equivalent circuit for the ring resonator is proposed and analyzed based on the electromagnetic phenomenon of the resonator. The equivalent circuit was simply modeled based on the concept of magnetization. A method for achieving a wider operating bandwidth of the negative permeability is provided. The ring resonator with its resonant frequency of 13.56 MHz was designed and its characteristics were examined in terms of S-parameters, effective permeability, loss rate, bandwidth, etc. The circuit and electromagnetic simulation results show an excellent agreement as well as that of theory.