The phenomenon of electromagnetic interferences
Depending on the kind of coupling of electromagnetic disturbances the phenomenon are divided into two different groups. In case the disturbance signal is air-borne one speaks of radiated interference while in case of disturbance signals are line-carried one speaks of conducted interference.

Where the coupling is radiation
Stationary and non-stationary radio transmitters (Electrical Field)
Both stationary high-power radio transmitters and non-stationary walkie-talkies or ecommunication devices operating in the immediate vicinity of systems or equipment lead to uncontrolled electromagnetic radiation into vulnerable electronic equipment.
Parameters: Narrow-band, continuous electromagnetic interference (modulated).
Standard reference: IEC/EN 61000-4-3 

HV power supply transmission lines (Magnetic Field) 
In the close vicinity to these lines high magnetic fields can be generated and coupled into other electronic or electrical systems.
Parameters: Narrow-band with 16 2/3Hz or 50/60Hz, continuous electromagnetic interference
Standard reference: IEC/EN 61000-4-8 

Indirect lightning effects (pulsed Magnetic Field) 
Lightning strokes into HV voltage power distribution systems are causing high electromagnetic fields which are able to cause induced voltage in any low voltage distribution system, such as power mains systems. Also ecom networks, due to the extended distribution of cabling, are threatened by indirect lightning effects.
Parameters: Range of voltage some tens of kilovolts, range of current some hundreds of amps, high-energy pulses with rise times in the microsecond range.
Standard reference: IEC/EN 61000-4-9

Where the coupling is conduction
Inductive load switching results in Electrical fast transients (burst)
Electromagnetic influences produced in the neighborhood by rapid variation of voltage and current as a result of the abrupt change of a switch from a non-conductive to a fully conductive status or vice versa, e.g. switching inductive loads with mechanically moved contacts between which arcing occurs before they separate.
Parameters: Broad-band pulse interference, rise time of pulses of a few nanoseconds, small energy content and high repetition rate.
Standard reference: IEC/EN 61000-4-4 

Switching inductive or capacitive loads in power mains supply system 
Switching heavy inductive or capacitive loads in low voltage power mains supply systems are causing transients of high energy and high voltage, depending on the installation category.
Parameters: Range of voltage some up to tens of kilovolts, range of current some tens of kilo amps, high-energy pulses with rise time and duration in the microsecond range.
Standard reference: IEC/EN 61000-4-5 

Atmospheric discharges such as lightning 
Lightning strokes into high voltage power distribution systems are causing transients in low voltage power mains networks. Via coupling these transients can also be detected in data bus systems, I/O lines and any cabling in the industrial area.
Parameters: Range of voltage some tens of kilovolts, range of current some tens of kilo amps, high-energy pulses with rise times in the microsecond range.
Standard reference: IEC/EN 61000-4-5 

Power Mains supply failures 
Voltage dips and short interruptions are caused by faults in the network, in installations or by a sudden large change of load. In certain cases, two or more consecutive dips or interruptions may occur. Voltage variations are caused by continuously varying loads connected to the mains supply network.
Parameters: These phenomena are random in nature and can be characterized in terms of the deviation from the rated voltage and duration.
Standard reference: IEC/EN 61000-4-11 

Electrostatic discharge 
ESD occurs when the static electric field between two objects exceeds the dielectric strength of the air between them. The discharge is a complex event involving a local transfer of charge at the point of discharge, electromagnetic near field coupling between the objects involved, induced current flow in the object receiving the discharge and radiated electromagnetic energy from the charged object as well as from the arc of the discharge. All of these phenomenon are capable of causing malfunctions and, in some cases, damage in electronic equipment.
Parameters: The major effects are generated by the discharge current (< 100A) and voltage (< 30kV) with rise times in the nanosecond and even in the picosecond range.
Standard reference: IEC/EN 61000-4-2 

Conducted disturbances, induced by radio-frequency fields 
Conducted radio-frequency disturbance occurs from intended rf transmitters affecting cables such as mains supply lines, signal lines or earth connections between different parts of an electrical or electronic systems.
Parameters: The interference signal is a an amplitude modulated or pulse modulated signal, typically in the frequency range between 9kHz and 80MHz, sometimes extended to 230MHz.
Standard reference: IEC/EN 61000-4-6 

Harmonic current emission 
With an increasing number of electronic power supplies used in a wide range of products the aim to limit the harmonic current emission has become more and more important. It is a specific interest of the power distribution companies to keep the harmonic current emission to a considerable low level as harmonic current causes unnecessary loading of the power distribution infrastructure. This again may affect both quality and reliability of the power supply.
Parameters: Harmonic currents are measured up to the 40th harmonic of the fundamental. Limits for each harmonic are specified depending on the type of product.
Standard reference: IEC/EN 61000-3-2, IEC/EN 61000-3-12 

Voltage changes, voltage fluctuation and flicker 
During an entire duty-cycle of a product sudden voltage changes, voltage fluctuations or flicker might occur. This may effect the quality of the mains supply voltage. Flicker can be visually recognized as the illumination strength of a lamp may drop significantly even for a very short time. To keep such phenomenon to the minimum limits have been introduced for the impact of load variations to the public mains supply network.
Standard reference: IEC/EN 61000-3-3, IEC/EN 61000-3-11

Additional Phenomena - EMC in Vehicles
Apart from the basic phenomena as described here above a wide range of additional requirements can be found for special electrical and electronic systems such as vehicles. These requirements are based on the fact that within a vehicles supply system a large number of sub-systems and components are installed generating interference and at the same time being exposed to interference. Some of the phenomena that can be found on-board vehicles look similar to the ones that are specified in the basic standards of IEC. Some are specific for thes systems.

Many vehicle manufacturers have set up their own EMC requirements for both conducted and radiated immunity and emission testing. These requirements supersede the national and international standards existing for EMC testing on vehicles (e.g. ISO7637, SAE J1113, JASO).

電磁幹擾現象
根(gēn)據電磁幹(gān)擾的(dí)耦合(hé)類(lèi)型，這種(zhǒng)現象被(bèi)分成兩(liǎng)個(gè)不同(tóng)的組。如果幹擾信(xìn)號是空(kōng)氣傳(chuán)播的，可以說(shuō)是輻(fú)射幹(gān)擾，而當幹(gān)擾信號是帶綫的(dí)時，則說傳(chuán)導(dǎo)幹(gān)擾(rǎo)。

耦合(hé)輻(fú)射(shè)的地方
固定和非平穩(wěn)無綫電發射(shè)機（電場(cháng)）
固(gù)定(dìng)大(dà)功(gōng)率無綫電發射機和(hé)非(fēi)平穩的對講(jiǎng)機或(huò)移動通信設備立即係統(tǒng)或(huò)設備附近操作導致不(bù)受控(kòng)製(zhì)的電磁(cí)輻(fú)射為脆(cuì)弱的(dí)電(diàn)子設(shè)備。
參數(shù)：窄帶，連續(xù)電(diàn)磁幹擾(rǎo)（調製(zhì)）。
參(cān)考標(biāo)準：IEC / EN 61000-4-3

高壓電源傳輸綫（磁(cí)場）
在(zài)這些綫附近，可以產生高(gāo)磁(cí)場並(bìng)耦合到(dào)其(qí)他電(diàn)子(zǐ)或(huò)電氣係統中。
參數：16 2 / 3hz或(huò)50／60Hz頻帶窄(zhǎi)，連續的電磁(cí)幹擾
參考標(biāo)準：IEC / EN 61000-4-8

間(jiān)接(jiē)閃電效應(yīng)（脈(mài)衝(chōng)磁場(cháng)）
高(gāo)壓(yā)高壓(yā)配電(diàn)係統的雷(léi)擊引起了高電(diàn)壓(yā)的電磁場(cháng)，它能在任(rèn)何低壓配(pèi)電(diàn)係統(tǒng)，如電(diàn)力係統(tǒng)中(zhōng)引起感(gǎn)應電(diàn)壓。此(cǐ)外，由(yóu)於(yú)布(bù)綫的(dí)廣(guǎng)泛(fàn)分布(bù)，電(diàn)信(xìn)網(wǎng)絡(luò)也(yě)受到(dào)間接閃電效應的威脅(xié)。
參(cān)數(shù)：電壓(yā)伏(fú)數範(fàn)圍內(nèi)，目前有數百(bǎi)安(ān)培範圍，在(zài)微(wēi)秒範圍內(nèi)的高能(néng)脈(mài)衝上升時間(jiān)。
參考(kǎo)標(biāo)準(zhǔn)：IEC / EN 61000-4-9

耦合在(zài)傳(chuán)導(dǎo)的(dí)地方(fāng)
感應負(fù)載開(kāi)關導致電快速瞬變（猝(cù)發）
由於開(kāi)關(guān)從非(fēi)導(dǎo)電(diàn)到(dào)*導電(diàn)狀(zhuàng)態的突然變化(huà)而引起的電壓(yā)和電(diàn)流的(dí)快速變化，在(zài)鄰近(jìn)地(dì)區(qū)產生(shēng)電磁(cí)影響(xiǎng)，例如在(zài)機械分(fēn)離觸點(diǎn)上切換感(gǎn)應負載(zǎi)，在(zài)它們分(fēn)開之(zhī)前發生電弧。
參數：寬帶脈衝幹擾(rǎo)，對幾納(nà)秒(miǎo)脈(mài)衝(chōng)的(dí)上升(shēng)時間，小的能量含量(liáng)和高(gāo)重(zhòng)復(fù)率。
參考標(biāo)準：IEC / EN 61000-4-4

電源係統(tǒng)中開(kāi)關感性負載(zǎi)或電容性負(fù)載
在(zài)低壓電(diàn)源係統中切(qiē)換(huàn)重(zhòng)感性或(huò)容(róng)性(xìng)負載(zǎi)，會引起高(gāo)能量(liáng)和高電壓的瞬(shùn)變，這取(qǔ)決於安裝(zhuāng)類(lèi)別(bié)。
參數：電(diàn)壓有的高達幾(jī)十千伏的範圍(wéi)內，電流(liú)安(ān)培(péi)數(shù)公斤的(dí)一些(xiē)範圍，在(zài)微秒範圍內(nèi)的高(gāo)能脈衝上(shàng)升時(shí)間(jiān)和持(chí)續(xù)時(shí)間(jiān)。
參考標準：IEC / EN 61000-4-5

大氣放(fàng)電，如閃電(diàn)
高壓配電係統的(dí)雷擊(jī)導致低壓(yā)電網的(dí)瞬變。通過(guò)耦(ǒu)合，這些瞬(shùn)變(biàn)也可(kě)以在數據總綫係統(tǒng)，I/O綫和(hé)工業區的任(rèn)何(hé)布綫中檢(jiǎn)測到(dào)。
參(cān)數(shù)：電壓(yā)伏數範圍(wéi)內，電(diàn)流(liú)安(ān)培數(shù)公斤(jīn)的(dí)一些範(fàn)圍，在(zài)微秒(miǎo)範圍內(nèi)的(dí)高(gāo)能(néng)脈衝上(shàng)升時間。
參考(kǎo)標(biāo)準：IEC / EN 61000-4-5

電(diàn)源(yuán)故(gù)障(zhàng)
電(diàn)壓驟降(jiàng)和(hé)短(duǎn)時(shí)中斷是由(yóu)網絡(luò)故障，裝置(zhì)故(gù)障(zhàng)或突然大負荷變(biàn)化(huà)引起的。在(zài)某些情況(kuàng)下，可能發(fā)生(shēng)兩(liǎng)次或多次連(lián)續的驟降(jiàng)或中(zhōng)斷。電(diàn)壓變化是由(yóu)於(yú)不(bù)斷變化的負(fù)載連(lián)接到電源供應(yīng)網絡(luò)引(yǐn)起的。
參(cān)數：這些現(xiàn)象本質(zhì)上(shàng)是隨機(jī)的，可(kě)以用(yòng)額(é)定電(diàn)壓和持續(xù)時(shí)間的偏差來(lái)表征(zhēng)。
參考(kǎo)標準(zhǔn)：IEC / EN 61000-4-11

靜(jìng)電放(fàng)電
靜(jìng)電放(fàng)電發(fā)生(shēng)在兩(liǎng)個物(wù)體(tǐ)之間(jiān)的靜電電場超過(guò)它們(mén)之間的空(kōng)氣(qì)的(dí)介電(diàn)強度(dù)時。放(fàng)電是一個復(fù)雜的(dí)事(shì)件，包(bāo)括(kuò)在(zài)放電點的局部電(diàn)荷轉(zhuǎn)移，涉及對(duì)象之(zhī)間(jiān)的電磁近場(cháng)耦合，接收(shōu)物(wù)體(tǐ)的感應電(diàn)流，從(cóng)帶電物體和(hé)放(fàng)電(diàn)電弧(hú)發(fā)射電磁能量(liáng)。所有這些現象都(dū)會導致故障，在某些情況下也會損壞電(diàn)子設(shè)備。
參(cān)數(shù)：主要(yào)作用是(shì)通過電流產(chǎn)生(shēng)的（小於100A）和(hé)電壓(yā)（＜30kV）上升時間(jiān)在納秒甚至皮(pí)秒(miǎo)範圍。
標準：參照IEC/EN 61000-4-2

射(shè)頻場引起的傳導騷(sāo)擾
傳導無綫電頻率幹擾(rǎo)來自預期的射頻發射機影響(xiǎng)電纜(lǎn)，如(rú)電力(lì)供(gōng)應綫，信(xìn)號(hào)綫或(huò)電氣或(huò)電(diàn)子(zǐ)係(xì)統不同部分之(zhī)間的地(dì)綫(xiàn)連接(jiē)。
參數(shù)：幹擾信號(hào)是(shì)一個振(zhèn)幅調製(zhì)或脈(mài)衝調製信(xìn)號，通常在9kHz和80MHz的頻率之(zhī)間的(dí)頻(pín)率(shuài)範(fàn)圍(wéi)，有(yǒu)時(shí)擴(kuò)展230 MHZ。
參考(kǎo)標準(zhǔn)：IEC / EN 61000-4-6

諧波(bō)電流發(fā)射
隨著(zhuó)越(yuè)來越多(duō)的(dí)電(diàn)子(zǐ)電源應用於廣泛的(dí)產品，限(xiàn)製(zhì)諧(xié)波電流(liú)發(fā)射的(dí)目(mù)標(biāo)變(biàn)得(dé)越(yuè)來越(yuè)重(zhòng)要(yào)。由(yóu)於諧波電流(liú)對(duì)配電(diàn)網(wǎng)基(jī)礎設施造成(chéng)不必要的負荷，使(shǐ)配電網的諧波(bō)電流降(jiàng)到相(xiāng)當(dāng)低的(dí)水平是電(diàn)力企(qǐ)業的一個(gè)特殊(shū)利益(yì)。這又(yòu)可能(néng)影(yǐng)響(xiǎng)電(diàn)源的(dí)質量和可靠(kào)性(xìng)。
參(cān)數(shù)：諧(xié)波電流(liú)測量到(dào)基波的第(dì)四(sì)十(shí)諧(xié)波。每個(gè)諧(xié)波的限製取決(jué)於產(chǎn)品的類(lèi)型(xíng)。
參考(kǎo)標準：IEC / EN 61000-3-2標準(zhǔn)，IEC / EN 61000-3-12

電壓(yā)變(biàn)化，電壓(yā)波(bō)動和閃變(biàn)
在產品的(dí)整個(gè)工(gōng)作(zuò)周(zhōu)期內，可能(néng)突然發生(shēng)電壓變(biàn)化(huà)，電壓(yā)波動(dòng)或閃(shǎn)變。這(zhè)可(kě)能會影響電源供電電(diàn)壓的(dí)質量。閃(shǎn)爍可以在視覺上被(bèi)識(shí)別(bié)，因為(wéi)燈(dēng)的照明(míng)強度即(jí)使在很(hěn)短(duǎn)的時(shí)間(jiān)內(nèi)也會顯(xiǎn)著下(xià)降。為了(liǎo)使負(fù)荷變化(huà)對(duì)公(gōng)共(gòng)供(gōng)電(diàn)網絡(luò)的影(yǐng)響(xiǎng)，必(bì)須將(jiāng)這(zhè)種(zhǒng)現象保(bǎo)持在(zài)zui低(dī)限(xiàn)度。
參考標(biāo)準(zhǔn)：IEC / EN 61000-3-3，IEC / EN 61000-3-11

附(fù)加(jiā)現(xiàn)象-車輛電磁(cí)兼容性(xìng)
除(chú)了如上所述(shù)的基本現(xiàn)象外(wài)，對於特(tè)殊(shū)的(dí)電(diàn)氣和電子係統，如車輛(liàng)，也可(kě)找到廣(guǎng)泛的附加要求。這些(xiē)要求基(jī)於這(zhè)樣一(yī)個事實：在車(chē)輛供(gōng)應係統(tǒng)中，安(ān)裝了大量的子(zǐ)係統和組(zǔ)件，產(chǎn)生(shēng)幹(gān)擾，同時(shí)又受到(dào)幹(gān)擾(rǎo)。在車載車(chē)輛(liàng)上(shàng)發現的一些現象與(yǔ)IEC標準中所規定(dìng)的類似(sì)。有(yǒu)些是專為這(zhè)些(xiē)係(xì)統(tǒng)。

許多汽車製造商(shāng)已(yǐ)經建立了自己(jǐ)的(dí)EMC要求進(jìn)行(háng)傳導和(hé)輻射免疫(yì)力和排(pái)放測(cè)試。這(zhè)些要求取代現有的(dí)國(guó)家(jiā)標準和(hé)標準EMC測試車(chē)輛(liàng)（如(rú)ISO7637，SAE j1113，JASO）。