Showing papers on "Electromagnetic compatibility published in 1995"

Electromagnetic Compatibility in Power Electronics

Abstract: Introduction History of EMC standardisation efforts Description of electromagnetic disturbances Conducted EMI measurement EMI in power electronic equipment EMI filter elements Noise suppression EMI filter circuit selection and measurement EMI filter design Testing for susceptibility to power line disturbances Reduction techniques for internal EMI Transient susceptibility analysis method Bibliography Index

On the contribution of the electromagnetic field components in field-to-transmission line interaction

Abstract: Based on the transmission line approximation, three different equivalent formulations have been proposed for evaluating the interaction between an external electromagnetic field and a transmission line, The difference among these "coupling" formulations, which are summarized for the case of a lossless line, lies essentially in the representation of the source terms as a function of the external electromagnetic field components. The authors show that the contribution of a given electromagnetic field component is different depending on the particular adopted formulation, To show that, the three formulations are employed to calculate the voltages induced on an overhead line by a nearby lightning strike, and the contribution to the induced voltage of the various electromagnetic field components explicitly appearing in each formulation is emphasized. The authors conclude that it is misleading to speak about the contribution of a given electromagnetic field component to the total induced voltages without first specifying the coupling formulation one is using.

Electronic device having the electromagnetic interference suppressing body

Abstract: An electromagnetic interference suppressing body is provided for suppressing electromagnetic interference by undesirable electromagnetic waves. The body can have a conductive support element and a non-conductive soft magnetic layer provided on at least one surface. The electromagnetic interference suppressing body may be used in circuit board electronic equipment and in a hybrid integrated circuit element having an active element and a passive element mounted on a circuit board.

Electronic systems failures and anomalies attributed to electromagnetic interference

Abstract: The effects of electromagnetic interference can be very detrimental to electronic systems utilized in space missions. Assuring that subsystems and systems are electrically compatible is an important engineering function necessary to assure mission success. This reference publication will acquaint the reader with spacecraft electronic systems failures and anomalies caused by electromagnetic interference and will show the importance of electromagnetic compatibility activities in conjunction with space flight programs. It is also hoped that the report will illustrate that evolving electronic systems are increasingly sensitive to electromagnetic interference and that NASA personnel must continue to diligently pursue electromagnetic compatibility on space flight systems.

Literal solutions for the time-domain response of a two-conductor transmission line excited by an incident electromagnetic field

Abstract: Analytical solutions of the transmission line equations for a lossless, two-conductor transmission-line with incident electromagnetic field illumination are obtained. The equations for the terminal voltages are in terms of symbols, rather than numerical values. This form of the solution gives insight into the various factors that contribute to the overall, time-domain response waveshape that would be obscured in a numerical solution. The results are specialized to uniform plane wave illumination and to electrically short lines. >

FD-TD analysis of electromagnetic radiation from modules-on-backplane configurations

Abstract: The electromagnetic radiation from a modules-on-backplane configuration found in computers is analyzed by means of the finite-difference time-domain (FD-TD) technique. The issues pertaining to the effects of the modules in influencing the overall radiating capacity of the configuration are addressed. Analyses are facilitated by using simplified modules-on-backplane models and by using a voltage source as the source of electromagnetic energy at a connector between a module and the backplane. The potential for enhancement of spurious emissions by the module-on-backplane configuration is demonstrated. For modules of typical dimensions, resonance is observed at the hundreds of MHz frequency range. Comparisons between numerical predictions and measurements are conducted to validate the numerical method. >

Grounding structures for the EMC-protection of cabling and wiring

Abstract: • A submitted manuscript is the version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers.

Cable Shielding for Electromagnetic Compatibility

Abstract: The first € price and the £ and $ price are net prices, subject to local VAT. Prices indicated with * include VAT for books; the €(D) includes 7% for Germany, the €(A) includes 10% for Austria. Prices indicated with ** include VAT for electronic products; 19% for Germany, 20% for Austria. All prices exclusive of carriage charges. Prices and other details are subject to change without notice. All errors and omissions excepted. A. Tsaliovich Cable Shielding for Electromagnetic Compatibility

On the prediction of digital circuit susceptibility to radiated EMI

Abstract: The effects of radiated radio-frequency interference (RFI) on the operation of digital systems are studied by simulating the response of simple logic circuits to incident plane waves. The simulation is accomplished by combining a linear electromagnetic moment-method model of the wire structure with a nonlinear circuit model of the solid-state components. The complete model is analyzed in the linear and nonlinear regimes as an example. It is shown how a circuit simulator, such as SPICE, can be used in the analysis of an arbitrary wire network loaded with logic circuits, by the process of representing the linear wire network as a lumped-element N-port /spl pi/ network and interfacing it to the nonlinear circuit simulator. Examples are given that demonstrate the occurrence of both static and dynamic failures under various RFI-field excitations and wire structure geometries. The prediction methods presented in this paper, can be used by EMC engineers to assess the likelihood of failures in RFI-exposed digital systems,.

Electromagnetic topology: investigations of nonuniform transmission line networks

Abstract: The electromagnetic topology approach is often used to calculate the current or voltage that can appear on a transmission line network illuminated by a disturbing wave. However the lines are supposed to be parallel to a ground plane and, furthermore, the model has often been applied on canonical cases. A generalization of this formalism to treat nonuniform transmission lines is presented. Moreover, by treating a wiring installed inside a Transall airplane mockup, a comparison between theoretical and experimental results shows the validity and the interest of this approach. >

The measured and predicted electromagnetic environment at urban hospitals

Abstract: The need for electromagnetic compatibility (EMC) is crucial in health care environments, since electromagnetic interference (EMI) effects on critical care medical equipment may be life-threatening. Field strength measurements, made inside and outside five Montreal hospitals at frequencies between 30-1000 MHz, were compared to fields predicted using line-of-sight, and hybrid methods. Although measured fields generally remained below 3 V/m, EMI still caused medical equipment malfunctions at the five hospitals. The line-of-sight prediction method provided a worst-case estimate of the electromagnetic environmental hazard, predicting outside fields to within 20 dB of those measured. The hybrid method predicted fields to within 10 dB.

Noise radar with correlation receiver as the basis of car collision avoidance system

Abstract: Noise radar is suggested as the basis for development of car collision avoidance system. Laboratory model of noise radar with correlation processing of the reflected signal with bandwidth up to 200MHz, which provide the range resolution better than one meter, was created and tested. Single transmitting-receiving unit allows to measure a distance to a target and it velocity simultaneously. The tests conducted showed that the noise radar technology is the most suitable one for development of car collision avoidance system due to it relative simplicity, high sensitivity and immunity against electromagnetic interferences, as well as good electromagnetic compatibility characteristics, small sizes, light weights and low cost.

Numerical methods to evaluate the electromagnetic fields below overhead transmission lines and their measurement

Abstract: An increasing sensibility to ecological problems is seen. In the phase of planning high-voltage lines, the magnetic and electric field quantities have to be examined in order to avoid EMC problems with the surroundings of the power line. This request becomes even more important with the trend towards higher transmission line voltages. In this paper, the computation of the electric and magnetic field distribution below AC high-voltage lines is demonstrated. Advantages and disadvantages of two different methods able to evaluate the field quantities are described. The first discussed method, a semi numerical method using the laws of electrostatic techniques to simulate the three dimensional field distribution below the overhead line and second, the finite element method using specific boundary conditions to compute the two dimensional field distribution in an efficient way are under consideration. Results from both techniques are compared to measured data to verify the computed field values.

The transient electromagnetic field produced by a moving pulse of line current

Abstract: The transient electromagnetic field produced by a current pulse moving along a straight line is considered. The algorithm for constructing the components of the electromagnetic field is given. This algorithm enables us to obtain directly the space-time representation of the electromagnetic pulse and to reveal the peculiarities of its dependence on the source-current characteristics.

The simulation of circuit breaker switching using a composite Cassie-modified Mayr model

Abstract: In substation electromagnetic compatibility studies or insulation coordination studies it is desirable to obtain as accurate a representation as possible of the transients generated by faults and switching events. A method of simulating the voltage and current transients generated by gas blast circuit breaker operation using a composite Cassie-modified Mayr model of the circuit breaker arc is described. It is demonstrated that this gives good agreement with published laboratory measurements of the circuit breaker voltage and current. The transmission line modelling method is used in the construction of the simulation algorithm of the circuit breaker circuit. A method, based on describing the circuit breaker using a transmission-line model is used to decouple the nonlinear characteristics from the rest of the network. >

Common mode inductor material selection

Abstract: As government agencies continue to tighten the requirements for electromagnetic compatibility, design engineers are forced to pay closer attention to the emissions created by their products. This is particularly true for DC-DC converters. Their high switching frequencies and steep pulse slopes are an excellent breeding ground for EMI. One important component in the suppression of electromagnetic interference (EMI), is the common mode inductor. It offers a very high impedance over a wide frequency range and is an integral part of most EMI filters. This report explains the methods used in selecting materials for common mode inductors.

Marshall Space Flight Center Electromagnetic Compatibility Design and Interference Control (MEDIC) handbook

Abstract: The purpose of the MEDIC Handbook is to provide practical and helpful information in the design of electrical equipment for electromagnetic compatibility (EMS). Included is the definition of electromagnetic interference (EMI) terms and units as well as an explanation of the basic EMI interactions. An overview of typical NASA EMI test requirements and associated test setups is given. General design techniques to minimize the risk of EMI and EMI suppression techniques at the board and equipment interface levels are presented. The Handbook contains specific EMI test compliance design techniques and retrofit fixes for noncompliant equipment. Also presented are special tests that are useful in the design process or in instances of specification noncompliance.

Electromagnetic Compatibility in Medical Equipment: A Guide for Designers and Installers

Abstract: INTRODUCTION What are the Threats? Sources, Paths, and Receptors Summary EMI STANDARDS FOR MEDICAL DEVICES Emissions vs Immunity The EU and the U.S. The EU U.S. Requirements Summary THE PHYSICS OF EMI Source-Path-Receptor The Nature of Interference Interference is a Current FAT-ID Summary COMPONENTS AND CIRCUITS Passive Components Transient Devices Active Components EMI Filter Design Summary PRINTED CIRCUIT BOARD DESIGN Signal Integrity vs EMI EMI Issues in Printed Circuit Boards Digital Circuits Analog Circuits Where Analog Meets Digital PCB Partitioning and Critical Circuits PCB Construction Multilayer Board Stackup Isolated Planes Two-Layer Board Techniques Power Decoupling Signal Traces I/O Techniques Board Shielding Software Summary GROUNDING FOR EMI CONTROL What is a Ground? Different Types of Grounds Microshock Hazards - A Special Medical Grounding Concern What Makes a Good Ground? Ground Topologies Bonding Considerations Grounding Design and Guidelines Summary POWER AND POWER FILTERING Power Supplies Switching Topologies Interference in Power Supplies Controlling Interference Generation Immunity Protection Filters Summary INTERCONNECT AND MOUNTING Cables as Transmission Lines Common Mode and Differential Mode on Cables Cable Layout and Pinouts Signal Bandwidth Routing Your Cable Designing an Enclosure Summary SHIELDING AND SHIELDING MATERIALS The Physics of Shielding Estimating the Impedance of a Source Shielding Requirements Shielding Materials Where Shielding Fails Gasketing Perforations and Screens Cable Penetrations Grounding the Shield How Much Shielding is Needed? Partial Shields Local Shields Summary CABLES AND CONNECTIONS Cables as Antennas Common Mode vs Differential Mode Bandwidth Classifying Cables Cable Shielding and Connectors Cable Terminations Cable Design Recommendations Summary SPECIAL EMI PROBLEMS IN MEDICAL ELECTRONICS High Energy Interference Sources Electromechanical Devices Radio Sources Receiving Devices Leakage Current Limitations Coping with Internal Threats Coping with External Threats Summary SYSTEMS CONSIDERATIONS Identifying EMI Threats at the Site Site Preparation Maintaining Shielding Effectiveness Troubleshooting in the Field When System Fixes Will Not Work Summary Glossary Appendix A: References for EMC Publications Appendix B: Properties of Common Materials Appendix C: Constants and Conversions Appendix D: Miscellaneous Conversions

EMC aspects in a steel structure struck by lightning

Abstract: The EMC analysis of a complex steel structure struck by a direct lightning, based on a simulation model developed by the authors, is here presented. For this proposal, simulations of the resulted magnetic field, as a function of the time, in the places where the higher susceptibility equipment will be installed, considering different lightning struck points, are carried out and these results are compared with some established limits. Some conclusions are presented, pointing out the advantages of the considered EMI prediction model during the design of the electrical and electronic installations, when lightning effects should be considered.

Transient field coupling and crosstalk in lossy lines with arbitrary loads

Abstract: We extend the transient scattering analysis of a lossy multiconductor transmission line to the evaluation of the interference produced by a field illuminating the line. The external interference is described by suitable voltage wave sources that are readily computed in the time domain and do not affect the structure of the transient scattering equations. The proposed formulation fully exploits the advantages of the transient analysis based on the line matched scattering parameters, dealing effectively with low-loss lines and helping the understanding of the interference mechanism through the physical interpretation of the results. The simplicity and efficiency of our approach is evidenced by means of a numerical example of the external interferences on a realistic nonlinearly loaded highly mismatched 3-conductor interconnect.

EMC analysis in PCB designs using an expert system

Abstract: Electronic subsystems with present day's technology are quite complex and consists of many printed circuit boards. Incidentally printed circuit boards (PCBs) are the ones, which causes most of the electromagnetic interference (EMI) problems. However each sub systems must maintain electromagnetic compatibility (EMC) with other subsystems in order to perform as per the specifications in its intended electromagnetic environment and to meet international regulations. Identifying the potential problems at an earlier stage of the design cycle minimizes the need for design changes by saving time and money. A knowledge based system called EMC Expert, for predicting EMI problems and offering solutions at the design stage of the PCB is presented. EMC Expert is implemented on a HP9000/735 workstation using C++ under X-Windows/MOTIF and is used to analyze PCBs designed by DRDL/CAD centre.

Switched mode power supplies EMC analysis: near field modeling and experimental validation

Abstract: An EMC analysis of a switched mode power supplies (SMPS) is presented which shows the variation of the radiation patterns, near field spatial distributions and radiation properties as the SMPS's load is altered. Depending upon the loading, the SMPS exhibits magnetic or electric dipole behavior. Currents and fields calculated by an accurate prediction model are compared with those measured.

Tuned band reject powerline EMI filter

Abstract: This paper presents a novel concept of using frequency selective power line electromagnetic interference (EMI) filtering. The tuned EMI filtering technique has certain advantages over the conventional EMI filtering under specific interference conditions. Powerline EMI filters, in general, exhibit low pass filter characteristics. The tuned band-reject powerline EMI filter is found to offer electromagnetic compatibility (EMC) solution in the situation when a high order of power is coupled at a known frequency into the powerline. For the known interference frequency, the tuned filter is designed to offer a high order of attenuation.

An ultrawideband microwave-radar conceptual design

Abstract: The paper outlines the special considerations that characterize the design of an UWB radar for the detection of low altitude missiles over the sea. It discusses the factors which enter into the choice of frequency, and the selection of the transmitter, antenna, and receiver. Reviewed are signal processing issues concerning detection of UWB signals in noise and clutter, non-Doppler MTI based on the pulse-to-pulse change in range due to target motion, measurement of target height based on multipath time delay, and target recognition. The chief limitation of UWB radar that must be overcome before applications are viable is its poor electromagnetic compatibility (EMC).

Electromagnetic fields inside a large room with perfectly conducting walls

Abstract: This EUT report describes the development of a model which can be used for the calculation of the electromagnetic fields inside a perfectly conducting cavity. A modal analysis has been chosen for the determination of the Green's functions inside the three dimensional enclosure. Using these Green's functions, the electromagnetic fields are calculated. The Green's functions have been written as double series, which are slowly convergent near the source coordinates. Much attention is paid to the convergence properties of the series. It has been found that the convergence of the series is not only slow at the source coordinates but also at some other regions inside the cavity. An extraction technique has been used in order to improve the convergence properties of the Green's functions for a rectangular box cavity. Furthermore it has been shown that due to the presence of the multipath environment, the amplitudes of the electromagnetic fields change rapidly.

Fast-transient susceptibility of a D-type flip-flop

Abstract: Human electrostatic discharge (ESD) produces a transient current pulse with a very fast risetime, which can be a source of electromagnetic interference in digital devices. The focus of this paper is the radiated susceptibility of D-type flip-flops implemented in various CMOS and TTL logic technologies. A transient impulse was used to simulate the radiated field produced during an ESD event. A synchronized-disturbance testing methodology is developed that allows accurate control of the instant at which the disturbing signal is applied to the data input lines during an operational cycle of the circuit. The study reveals that these devices are susceptible only during certain time intervals during an operational cycle. The particular interval during which a flip-flop is susceptible is dependent on the logic state of the data input line, the implementation technology of the flip-flop, and the amplitude of the disturbing signal. The total width of the susceptibility intervals is a device parameter that can be used to determine the probability that the flip-flop will fail in the presence of random transient interference pulses. >

Stop that noise

Abstract: The authors discuss electromagnetic compatibility (EMC) and electromagnetic interference (EMI). After a brief look at the causes of EMI, they describe conductive coupling and electromagnetic radiative coupling. Career opportunities in EMC problem solving are looked at. >

Modelling for electromagnetic interference assessment in electric railway traction systems

Abstract: Electromagnetic field and circuit simulation models are described which enable a railway traction system with substations, traction drives, track signalling equipment, track and traction line to be assessed for low and audio frequency electromagnetic interference. The novel features are the derivation of frequency-dependent track and traction line impedance by the finite-element method of electromagnetic field analysis and the representation of the frequency dependency in circuit simulation by current-dependent voltage sources. Example interference spectra are given for cab signal current with audio frequency track signalling on a 3 kV DC traction system with 12-pulse rectifier substations and an inverter-fed traction drive.< >

Clock frequency coordination for electromagnetic compatibility

Abstract: A method for selecting fundamental clock frequencies in order to achieve electromagnetic compatibility in electronic products which employ a plurality of clocks. The method require first selecting an ideal frequency for each clock in the product. Then, and until the goal of avoiding coinciding harmonics is complete, the method includes the steps of computing all harmonics of all clock frequencies chosen, determining a minimum difference tolerable in the chosen frequencies and their harmonics for sufficient minimization of electromagnetic interference, and determining if the harmonics of the chosen frequencies coincide impermissibly within the frequency range. If there exists coincidence of harmonics within the predetermined minimum range, then the fundamental frequency of at least one of the clocks corresponding to an interfering harmonic must be adjusted to eliminate the interference. With the altered fundamental frequency, the steps of computing harmonics, determining if coincidence occurs, and adjusting the fundamental frequency is repeated.

Electromagnetic coupling between two half-space regions separated by multiple slot-perforated parallel conducting screens

Abstract: Considers the problem of electromagnetic coupling between two half-space regions separated by multiple slot-perforated parallel conducting screens. The fields are considered to be excited by either a transverse electric (TE) or a transverse magnetic (TM) plane wave. A characteristic mode solution is used for the computation of the fields in each half-space. Special attention is given to the power transmitted from one half-space to the other through the slots and to its functional dependence on various parameters. Numerical examples are presented for illustration and comparison. >