Electromagnetic Reinforced Carbon Fiber Composite Case and Its Electromagnetic Pulse Protection Performance

We adopt the technology of electromagnetic strengthening carbon fiber composite material to improve its electromagnetic protection ability, and use it to prepare the sample of carbon fiber composite cabinet, through the test, it has good electromagnetic pulse protection performance. Based on the carbon fiber composite structure design and electric connection design of the interlamination and gap electromagnetic enforcement. The HEMP protection performance was tested under the GB/T18039.10-2018 standard and the results showed that the HEMP shielding efficiency were above 65 dB. The carbon fiber composite cabinet had the lightweight ,high strength，HEMP shielding and anti-severe environment characteristics. The carbon fiber composite cabinet has a project value and application prospect

Aircraft electromagnetic compatibility

Illustrated are aircraft architecture, electromagnetic interference environments, electromagnetic compatibility protection techniques, program specifications, tasks, and verification and validation procedures. The environment of 400 Hz power, electrical transients, and radio frequency fields are portrayed and related to thresholds of avionics electronics. Five layers of protection for avionics are defined. Recognition is given to some present day electromagnetic compatibility weaknesses and issues which serve to reemphasize the importance of EMC verification of equipment and parts, and their ultimate EMC validation on the aircraft. Proven standards of grounding, bonding, shielding, wiring, and packaging are laid out to help provide a foundation for a comprehensive approach to successful future aircraft design and an understanding of cost effective EMC in an aircraft setting

Avionics system design for high energy fields: A guide for the designer and airworthiness specialist

Because of the significant differences in transient susceptibility, the use of digital electronics in flight critical systems, and the reduced shielding effects of composite materials, there is a definite need to define pracitices which will minimize electromagnetic susceptibility, to investigate the operational environment, and to develop appropriate testing methods for flight critical systems. The design practices which will lead to reduced electromagnetic susceptibility of avionics systems in high energy fields is described. The levels of emission that can be anticipated from generic digital devices. It is assumed that as data processing equipment becomes an ever larger part of the avionics package, the construction methods of the data processing industry will increasingly carry over into aircraft. In Appendix 1 tentative revisions to RTCA DO-160B, Environmental Conditions and Test Procedures for Airborne Equipment, are presented. These revisions are intended to safeguard flight critical systems from the effects of high energy electromagnetic fields. A very extensive and useful bibliography on both electromagnetic compatibility and avionics issues is included

Power quality and electromagnetic compatibility: special report, session 2

The scope of Session 2 (S2) has been defined as follows by the Session Advisory Group and the Technical Committee: Power Quality (PQ), with the more general concept of electromagnetic compatibility (EMC) and with some related safety problems in electricity distribution systems. Special focus is put on voltage continuity (supply reliability, problem of outages) and voltage quality (voltage level, flicker, unbalance, harmonics). This session will also look at electromagnetic compatibility (mains frequency to 150 kHz), electromagnetic interferences and electric and magnetic fields issues. Also addressed in this session are electrical safety and immunity concerns (lightning issues, step, touch and transferred voltages). The aim of this special report is to present a synthesis of the present concerns in PQ&EMC, based on all selected papers of session 2 and related papers from other sessions, (152 papers in total). The report is divided in the following 4 blocks: Block 1: Electric and Magnetic Fields, EMC, Earthing systems Block 2: Harmonics Block 3: Voltage Variation Block 4: Power Quality Monitoring Two Round Tables will be organised: - Power quality and EMC in the Future Grid (CIGRE/CIRED WG C4.24, RT 13) - Reliability Benchmarking - why we should do it? What should be done in future? (RT 15

Evaluation of Lightning Induced Effects in a Graphite Composite Fairing Structure

Defining the electromagnetic environment inside a graphite composite fairing due to lightning is of interest to spacecraft developers. This paper is the first in a two part series and studies the shielding effectiveness of a graphite composite model fairing using derived equivalent properties. A frequency domain Method of Moments (MoM) model is developed and comparisons are made with shielding test results obtained using a vehicle-like composite fairing. The comparison results show that the analytical models can adequately predict the test results. Both measured and model data indicate that graphite composite fairings provide significant attenuation to magnetic fields as frequency increases. Diffusion effects are also discussed. Part 2 examines the time domain based effects through the development of a loop based induced field testing and a Transmission-Line-Matrix (TLM) model is developed in the time domain to study how the composite fairing affects lightning induced magnetic fields. Comparisons are made with shielding test results obtained using a vehicle-like composite fairing in the time domain. The comparison results show that the analytical models can adequately predict the test and industry results

A Waveform Relaxation Solver for Transient Simulation of Large-Scale Nonlinearly Loaded Shielding Structures

This article introduces an algorithm for transient simulation of electromagnetic structures loaded by lumped nonlinear devices. The reference application is energy-selective shielding, which adopts clipping devices uniformly spread along shield apertures to achieve a shielding effectiveness that increases with the power of the incident field, thereby blocking high-power interference while allowing low-power communication. Transient simulation of such structures poses a number of challenges, related to their large-scale and low-loss nature. In this work, we propose a waveform relaxation (WR) scheme based on decoupling the linear electromagnetic structure from its nonlinear terminations. In a preprocessing stage, the electromagnetic subsystem is characterized in the frequency domain and converted into a behavioral rational macromodel. Transient simulation is performed by refining estimates of the port signals through iterations. The proposed scheme combines a time partitioning approach with an inexact Newton–Krylov solver. This combination provides fast convergence also in those cases where standard WR schemes fail due to a strong mismatch at the decoupling sections. Numerical results on several test cases of increasing complexity with up to 1024 ports show that the proposed approach proves as reliable as HSPICE in terms of accuracy, with a speedup ranging from one to three orders of magnitude

Radio Frequency Interference /RFI/ design guide for aerospace communications systems

Radio frequency interference design guide for aerospace communications system

디지털 엑스선 장비의 고압 케이블과 인접 신호 케이블간 Crosstalk 원인 및 대책

학위논문 (석사) -- 서울대학교 대학원 : 공학전문대학원 응용공학과, 2021. 2. 남상욱.The term medical equipment refers to the devices used for disease prevention, diagnosis, and treatment of humans or animals. These types of equipment are different from general electronic devices in terms of their intended purposes of use. This means that it is more important to diagnose and treat accurately and quickly rather than use superior performance or cutting-edge technologies. Clearly, the application of the latest technologies that emerge following advancements in the information technology industry cannot be ignored, but the stability and reliability of products are separate issues. Digital radiography (DR) is a system that consists of numerous circuits, cables, and electronic components. Because of its large scale and very complex structure, DR can potentially degrade the performance or damage other electronic devices owing to electromagnetic interference (EMI). In particular, noise mixed in high-voltage pulses for X-ray sources generated by the high-voltage generator (HVG) will propagates throughout the system, and cause EMI problems and malfunctions. Therefore, electromagnetic compatibility (EMC) for medical equipment products is a field directly related to product reliability. This study analyzes the causes of noise generated by the HVG used in DR systems. In addition, we suggest a solution for EMI noise reduction. This EMI noise couples with an adjacent cable through a high-voltage cable. Most of the EMI noise is reduced because the high-voltage cable in the DR system is shielded and has a high-optical coverage of 95\%. However, as the amplitude of the X-ray pulse reaches several tens of kV and the receptors load impedance is high enough in these typed of applications, it can be coupled to the adjacent signal cable and cause system malfunction. Therefore, in this study, we analyze the mechanism of coupling in the shielded cable, and determine the cause of the noise source and the type of coupling using equivalent circuit analysis. As a countermeasure to noise, we propose a method that satisfies both low cost and high reliability.의료기기는 사람이나 동물에게 단독 또는 조합하여 사용되는 장치를 말하며 질병 예방, 진단 및 치료에 목적을 두고 있다는 점에서 타 전자제품과는 차이가 있다. 이 말은 단순히 성능적으로 우수하고 다양한 최신 기술이 적용되는 것이 중요한 게 아니라 얼마나 정확하고 신속히 진단을 내리고 치료를 할 수 있느냐가 핵심이라는 것이다. 물론 IT 업계에서 매년 쏟아져 나오는 최신 기술을 적용하는 것도 무시할 수 없지만 제품의 안정성, 신뢰성과는 또 다른 이야기이다. Digital Radiography(DR)는 수많은 회로와 cable, 전장부품들로 이루어진 시스템으로 규모가 크고 구조가 매우 복잡하여 전자기 장애(EMI)로 인한 성능 저하나 타 전자기기에 피해를 줄 가능성을 많이 내포하고 있다. 특히 X-ray source 역할을 하는 high-voltage generator(HVG)로부터 발생하는 고전압 pulse는 DR 장비 전체로 퍼져 나가며 EMI 문제를 일으키고 오동작을 유발하곤 한다. 따라서 의료기기 제품에 있어 전자파 적합성(EMC)은 곧 제품의 신뢰성과 직결된 분야이다. 본 프로젝트 리포트는 DR 시스템에 사용되는 HVG에서 발생하는 noise의 원인과 high-voltage cable을 경로로 인접 cable까지 coupling 되는 EMI noise에 대한 정도 및 저감 대책을 분석하였다. High-voltage cable은 약 95%의 높은 Optical coverage로 shielding 처리가 되어 있어 상당 부분의 EMI noise가 저감된다. 그러나 X-ray pulse의 크기는 수십 kV에 달하고 noise의 주파수 또한 낮지 않기 때문에 인접한 signal cable로 시스템 오동작을 유발할 만큼 충분한 수준으로 noise가 유입될 수 있다. 따라서 본 프로젝트 리포트에서는 먼저 shielded cable에서 coupling이 발생하는 mechanism을 살펴보고 noise source의 경로 및 발생 원인, 그리고 등가회로 분석을 통한 coupling의 종류를 알아본다. 마지막으로 이에 대한 noise 저감 대책은 비용과 신뢰성 모두를 만족하게 할 방법을 제안한다.Abstract i Contents iii List of Tables v List of Figures vi 1 INTRODUCTION 1 1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1.1 Digital Radiography System . . . . . . . . . . . . . . . . . . 2 1.1.2 High-voltage Generator . . . . . . . . . . . . . . . . . . . . 3 1.1.3 High-voltage Cable . . . . . . . . . . . . . . . . . . . . . . . 4 1.2 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2 THEORETICAL BACKGROUND 7 2.1 Coupling Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.1.1 Capacitive Coupling . . . . . . . . . . . . . . . . . . . . . . 7 2.1.2 Inductive Coupling . . . . . . . . . . . . . . . . . . . . . . . 9 2.2 Effect of Shield . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 2.2.1 Structure of the Braided Shield . . . . . . . . . . . . . . . . . 13 2.2.2 Transfer Parameter . . . . . . . . . . . . . . . . . . . . . . . 15 2.2.3 Effect of the Shielding Condition . . . . . . . . . . . . . . . 20 2.3 Conduction Noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 2.3.1 Common-mode Noise . . . . . . . . . . . . . . . . . . . . . 29 2.3.2 Rectifier Diode Noise . . . . . . . . . . . . . . . . . . . . . . 30 3 ANALYSIS 33 3.1 Equivalent Circuit of Capacitive Coupling . . . . . . . . . . . . . . . 38 3.2 Equivalent Circuit of Inductive Coupling . . . . . . . . . . . . . . . . 38 3.3 Equivalent Circuit of Shield Interruption . . . . . . . . . . . . . . . . 41 4 EVALUATION 47 4.1 Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 4.1.1 Coupling Noise . . . . . . . . . . . . . . . . . . . . . . . . . 47 4.1.2 Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 4.2 Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 5 CONCLUSION 67 Abstract (In Korean) 71 Acknowlegement 73Maste

Mitigation Solutions for the Magnetic Field Produced by MFDC Spot Welding Guns

Among the different welding technologies, portable welding guns are one of the most critical devices in relation to human exposure to electromagnetic fields. This paper focuses on medium frequency (MF) direct current guns proposing two actions aimed to the mitigation of the magnetic field generated during the welding process. The first action consists in the adoption of a passive shield for the on-board MF transformer. The analysis points out that the transformer alone produces a magnetic field that can exceed the prescribed limits. Therefore, a suitable mitigation system is identified. The second action aims to mitigate the predominant magnetic field that is generated by the electrodes of the welding gun. The analysis of the field waveforms shows that the rise time of the welding current pulse is the main parameter affecting the exposure index. The effect of the increase of the rise time is investigated through experimental and numerical analyses. The results prove that a small increase of the rise time causes a significant reduction of the exposure level. It is noteworthy that the two mitigation actions can be adopted on both existing and newly developed welding guns as they do not require any structural modification of the welding device