Electromagnetic compatibility
The second class, susceptibility, is the tendency of electrical equipment, referred to as the victim, to malfunction or break down in the presence of unwanted emissions, which are known as Radio frequency interference (RFI).Switching devices became commonplace through the middle of the 20th century, typically in petrol powered cars and motorcycles but also in domestic appliances such as thermostats and refrigerators.ESD problems first arose with accidental electric spark discharges in hazardous environments such as coal mines and when refuelling aircraft or motor cars.After World War II the military became increasingly concerned with the effects of nuclear electromagnetic pulse (NEMP), lightning strike, and even high-powered radar beams, on vehicle and mobile equipment of all kinds, and especially aircraft electrical systems.Later, the International Telecommunication Union adopted a Recommendation providing limits of radiation from ISM devices in order to protect radiocommunications.A variety of issues such as sideband and harmonic emissions, broadband sources, and the ever-increasing popularity of electrical switching devices and their victims, resulted in a steady development of standards and laws.[3] This regulatory environment led to a sharp growth in the EMC industry supplying specialist devices and equipment, analysis and design software, and testing and certification services.In 1985, the USA released the ISM bands for low-power mobile digital communications, leading to the development of Wi-Fi and remotely-operated car door keys.Besides understanding the phenomena in themselves, EMC also addresses the countermeasures, such as control regimes, design and measurement, which should be taken in order to prevent emissions from causing any adverse effect.The control of electromagnetic interference (EMI) and assurance of EMC comprises a series of related disciplines: The risk posed by the threat is usually statistical in nature, so much of the work in threat characterisation and standards setting is based on reducing the probability of disruptive EMI to an acceptable level, rather than its assured elimination.Grounding and shielding aim to reduce emissions or divert EMI away from the victim by providing an alternative, low-impedance path.Typical antennas specified include dipole, biconical, log-periodic, double ridged guide and conical log-spiral designs.Transient or EMP signals are used to test the immunity of the DUT against powerline disturbances including surges, lightning strikes and switching noise.The Directive applies to a vast range of equipment including electrical and electronic appliances, systems and installations.Manufacturers of electric and electronic devices are advised to run EMC tests in order to comply with compulsory CE-labeling.In 2019, the USA adopted a program for the protection of critical infrastructure against an electromagnetic pulse, whether caused by a geomagnetic storm or a high-altitude nuclear weapon.
Log-periodic antennaelectromagnetic environmentelectromagnetic interferenceelectrical engineeringRadio frequency interferencelightningelectromagnetic pulseLightning rodselectricity generationshort-circuitcircuit breakersMarconiradio communicationsbroadcastelectric sparkmicrowave ovensmobile communicationserror-correctionnarrowbandbroadbandfrequency rangetransientdamped sine waveconductivecapacitivemagneticradiativeConductive couplingCapacitive couplingelectrical fieldvoltageInductive couplingmagnetic fieldelectromagnetic waveTV tuner cardS-VideoShieldedelastomericDecouplingRF chokesRC elementsline filterTransmission linewaterfall diagramswitchingspread spectrumHarmonicreverberationgigahertz transverse electromagnetic cellcomputational electromagneticscurrent clampdipolebiconicallog-periodicspectrum analyseroscilloscopetransformerElectrostatic dischargepiezo spark generatorESD pistolharmonizationInternational Electrotechnical CommissionComité International Spécial des Perturbations RadioélectriquesInternational Organization for StandardizationComité Européen de NormalisationComité Européen de Normalisation ElectrotechniquesEuropean Telecommunications Standards InstituteFederal Communications CommissionSociety of Automotive EngineersRadio Technical Commission for AeronauticsDO-160British Standards InstitutionVerband der Elektrotechnik, Elektronik und InformationstechnikEuropean lawEuropean Unionelectric and electronic devicesCE-labelinglist of EMC directivesgeomagnetic stormConducted electromagnetic interferenceCrosstalkIEEE Electromagnetic Compatibility SocietyInternational Commission on Non-Ionizing Radiation ProtectionList of common EMC test standardsTelevision interferencepublic domain materialUnited States GovernmentWayback Machine