• Journal of Electrical Engineering and Technology
• /
• 제12권3호
• /
• pp.1257-1261
• /
• 2017

This paper focuses on understanding the interrupting capability of an arc contact system in a molded case circuit breaker (hereafter MCCB). We selected four types of MCCBs and analyzed the magnetic flux density distributions in the contact systems caused by the fault currents. We ascertained that the magnetic flux density profile varies according to the shape of the contact system and was asymmetric at both the ends of an arc, perpendicular to the arc column because of the magnetic grid installed in the contact system. The asymmetric difference creates a magnetic force that pushes the arc current outwards and provides an interrupting capability. We have introduced a simple analysis method for determining the interrupting capability of the contact system for an MCCB by the arc-driving magnetic flux density.

• 한국진공학회지
• /
• 제8권4A호
• /
• pp.461-464
• /
• 1999

Planar type thin film inductors have a potential for the application of miniaturized DC-DC converters. For those high current applications, the magnetic film with high current capability is required. The current capability of magnetic films is mainly determined from high saturation magnetization (4$\piM_s$) as well as large anisotropy field $(H_k)$. We fabricated a double rectangular spiral thin film inductor which consist of magnetic layer, coil and insulator. Highest inductance values as well as best frequency characteristics can be obtained from 5 MHz and quality factor exhibit about 7.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2001년도 하계학술대회 논문집
• /
• pp.231-233
• /
• 2001

Axial magnetic field(AMF) type electrodes can be increase the interrupting capability of vacuum interrupters. Depending on the design, the principle of the local axial magnetic field arrangement are different. In this paper, a new AMF contact design based on a unipolar field arrangement and its characteristics are introduced. The influence of the unipolar AMF on the arc behavior is described by high-speed video camera. In addition, three-dimensional AMF simulations have been peformed by means of a finite element analysis(FEM) program to analyze the influence of magnetic field distribution on the AMF performance. The high interrupting capability of the unipolar AMF type electrode has been confirmed by three-phase test.

• 조명전기설비학회논문지
• /
• 제21권6호
• /
• pp.85-93
• /
• 2007

본 논문에서는 철심형 영구자석 선형동기전동기(PMLSM, Steel-Cored Permanent Magnet Linear Synchronous Motor)에서 운전 특성을 고려한 설계 특성 및 전략 등에 대한 내용을 다룬다. 특히 반송장치의 운송궤적에서 요구하는 동적특성과 전동기의 동적용량(Dynamic Capability)을 고려한 동적제약조건(Dynamic Constraints) 규정을 통하여, 짧은 변위의 급가감속 왕복운전을 위한 철심형 PMLSM의 최적설계 전략을 살펴본다. 이와 더불어 동특성이 두드러진 PMLSM의 설계특성으로 열적인 특성, 디텐트력 해석 및 저감, 그리고 자계의 포화특성에 대하여 추가 고찰한다.

• 한국전자통신학회논문지
• /
• 제12권6호
• /
• pp.1057-1064
• /
• 2017

거대자기임피던스 효과를 이용한 자기센서를 사용하여 자화된 금속이물질을 감지할 수 있는 고감도 금속이물질 감지 센서를 구현하였다. 스트립 형태의 센서는 지자기의 영향으로 스트립의 축방향이 놓인 위치에 따라 초기 직류전압은 다르게 나타났지만 접지점에 연결된 스트립에서 멀어질수록 외부 자계에 대한 출력전압이 증가하며 스트립의 축 방향에는 무관함을 나타내었다. 제안하는 자기센서는 고감도 실현을 위하여 능동잡음필터를 적용하여 기저잡음의 반 이상을 제거할 수 있었고 설치된 주변 환경에서 발생하는 전자기 잡음 및 지자기로 부터의 영향을 받지 않고 자화된 금속 이물질을 검출할 수 있음을 보여주었다. 자화된 철구의 경우 5mm 이격거리에서 지름 0.8mm 까지 감지가 가능함을 실험적으로 보여주었다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2001년도 하계학술대회 논문집 B
• /
• pp.672-674
• /
• 2001

Axial magnetic field(AMF) type electrode can increase the interrupting capability of vacuum interrupters. But, this interrupting capability vary with design parameters such as shape of electrode, slits of contact, material of contact and so on. In this paper, shown arc characteristics of unipolar axial magnetic field type electrode for vacuum interrupter by design parameters such as shape of contact slits and diameter of contact. And, confirmed vacuum arc configuration by individual design parameter using high speed camera.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 초전도 자성체
• /
• pp.83-87
• /
• 2002

In order to improve the capability of magnetic circuit, magnetic materials are used for all kinds of electromagnetic energy-conversion devices. This paper presents the analysis method considering magnetic properties of the magnetic material and analyzes that the effects of magnetic materials. In addition, it is described that the requirements of magnetic materials for the improvement of electric machines. Several application examples using a metal powder in electromagnetic energy conversion devices is introduced.

• Journal of Magnetics
• /
• 제18권4호
• /
• pp.432-442
• /
• 2013

For magnetically suspended flywheel (MSFW) with gimballing capability, demerits of Lorentz force-type magnetic bearings and common reluctance force-type magnetic bearings are analyzed, a novel reluctance forcetype magnetic bearing (RFMB) including radial and axial magnetic bearing units with 4 separate biased permanent magnets and two conical stators is presented. By equivalent magnetic circuits' method, its magnetic properties are analyzed. To reduce the eddy loss, it was designed as radial poles with shoes and its rotor made of Iron-based amorphousness. Although the uniformity of magnetic flux density in the conical air gap determines mainly the additional tilting torque, the maximum additional tilting torques is 0.05Nm and the rotor tilting has no influence on its forces when the rotor tilts or the maximum changes does not exceed 14% when the rotor drifts and tilts simultaneously. The MSFW with this RFMB can meet the maneuvering requirement of spacecraft theoretically.

• Journal of Magnetics
• /
• 제18권3호
• /
• pp.339-341
• /
• 2013

The magnetic field standards, facilities and capabilities available at NPL for the calibration of magnetometers and gradiometers and the measurement of the magnetic properties of materials will be introduced. The details of the low magnetic field facility will be explained and the capabilities this facility enables for the characterisation and calibration of ultra-sensitive room temperature magnetic sensors will be presented. Building on core material capabilities that are compliant with the IEC 60404 series of written standards, the example of a standard permeameter that has been modified for the measurement of strips for real world conditions is discussed. This was incorporated into a stress machine to measure the DC properties of the soft magnetic materials used by the partners of a collaborative industry led R&D project at stress levels of up to 700 MPa. The results for three materials are presented and the changes in the properties with applied stress compared to establish which material exhibits favourable properties.

• 한국초전도ㆍ저온공학회논문지
• /
• 제24권3호
• /
• pp.52-56
• /
• 2022

Single-grain (c-normal or c-parallel) and multi-grain YBCO superconductors were prepared by a melt growth process with/without seeding. The magnetic levitation force and trapped magnetic field at liquid N₂ temperature (77 K) of the YBCO superconductors were investigated. Samples for the levitation force measurement were zero-field cooled (ZFC) to 77 K, and samples for trapped field measurement were field-cooled (FC) using Nd magnets. As for the magnetic levitation force, the c-normal, single grain sample showed the largest value, whereas the multi-grain sample showed the lowest value. The trapped magnetic field of the c-normal and c-parallel single-grain samples was 4-5 times that of the multi-grain sample. In addition, as the external magnetic field (the number of magnets) increased, the both properties increased proportionally. These results were explained in terms of the orientation dependence of the levitation forces and the magnetic field trapping capability of the YBCO superconductor.