The first brand in Certification & Testing
About GTSMore>>  
Shanghai Global Testing Services Co., Ltd. (GTS) is an experienced certification authority focusing on providing the third party inspection, identification, test and certification service. We offer many testing services in the fields of industrial products, consumer goods, trade security, etc., involving harmful material, safety, EMC, material analysis, textile, shoes, leather, toys, and many other testing programs.
Certificate Explorer
Current Location:Shanghai Global Testing Services Co., Ltd. > Electromagnetic Compatibility >

 Electrical fast transient

Electrical fast transient

Introduction to Electrical Fast Transient

When a circuit is switched off, the current flowing through the switch is interrupted instantaneously. At the instantaneous of switching, an infinite dI/dt is generated. Some types of load, such as motors or solenoids, have considerably inductance. The voltage developed across an inductance L by a changing current I is


V = -L · dI/dt


If dI/dt is infinite, then this implies an infinitely high voltage. In reality, it doesn’t happen because the rate of the rise of voltage is limited by stray or intentional circuit capacitance.


Even so, a high instantaneous voltage, added to the circuit operating voltage, does appear across the opening switch contacts.


This causes the air gap across the contacts to break down, and a current flows again, which collapses the voltage spike, so that the briefly formed arc extinguishes. But this re-interrupts the current, so another voltage spike appears, creating a further arc.


This process repeats itself until the air gap is large enough to sustain the applied voltage without breakdown, at which point the circuit can be said to be properly switched off. The visible effect is a brief spark between the contacts, which actually consists of a whole series of microsparks, the so-called "showering arc", whose repetition rate and amplitude depend on the circuit and switch parameters.


The I(t) and v(t) inherent in each spark event propagate along the circuit wiring. If this is a mains circuit, this burst of noise can appear at other points of connection to the mains distribution ring. Also since the pulses are very fast – of the order of nanoseconds – they couple effectively to other wiring in close proximity to the circuit wiring.


Voltage peaks, typically of hundreds but occasionally thousands of volts, appear on any such coupled circuits.

Effect Of Electrical Fast Transient


It is possible for the transients to be coupled into a nearby electronics device by inductive coupling but, generally, they enter the product via the cable connections. On signal ports, the spikes are almost invariably in common mode, i.e. on all wires (or on the screen) at the same amplitude with respect to externalearth.


On the mains port, they may appear either in common mode or differentially between phases. Common mode coupling includes the protective earth wire.

Poor filtering or inadequate screen termination on each interface then lets these transients pass into the electronic circuits where they appear as interfering signals at sensitive nodes. As with other types of transient, digital circuits tend to be more susceptible, since each short pulse can appear as a valid digitalsignal.


Occurring in bursts, there is a higher probability that one or more pulses will coincide with a critical timing edge. However, analogue circuits can also be affected, typically by saturation of sensitive amplifiers. Pulse counting circuits are also susceptible if the burst masquerades as a real input.


Design Practice to Minimise Electrical Fast Transient Effect

In order to minimise the effect of electrical fast transient on electonics devices, the following steps should beadhered strictly to:

a) Internal circuit design is bandwidth limited wherever possible, and the PCB layout prevents large interference voltages from appearing within the circuit;

b) Interfaces must be filtered or screened to a structural low impedance earth so that common mode pulses are prevented from entering the circuit.

Electrical Fast Transient Testing Using IEC 61000-4-4 Standard

IEC 61000-4-4 basic standard for testing fast transient immunity. It applies a specified burst waveform via a defined coupling network to the mains connection and via a defined clamp device to any signal connection.


Only conducted coupling is used. Choice of ports for the application of the burst depends on the instructions in the product standard being used, but it is generally applied to AC and DC power ports and to signal and control ports that may be connected to cables longer than 3m.


There are many accreditated test labs around which will be able to provide the Electrical Fast Transient test according to IEC 61000-4-4 specifications for a fee. Make sure that the labs are accreditated before you embark in testing your products otherwise the test results may not be recognized by the approval bodies.


About Shanghai Global Testing Services Co., Ltd. |  Customer Service |  Law acknowledge |  Terms of use |  Contact |  Site map |  CE certification company
Tel:021-33637866  021-33637858 Technical support:vi-can
Copyright ? 2008-2012  About Shanghai Global Testing Services Co., Ltd. All Rights Reserved Add:Floor 2nd,Building D-1,No.128,Shenfu Road,Minhang District,Shanghai,China.
  • QQ咨詢

  • 點擊這里給我發消息
  • 點擊這里給我發消息
  • 電話咨詢

  • 400-618-3600
  • 服務時間
  • 09:00-19:00
A级毛片_黄,免费观看分类精品_一本道无码一级片_A级高清免费毛片av无码 奇米在线观看免费观看,奇米热免费视频在线播放,蝌蚪窝奇米网在线视频,奇米影视第四色首页在线播放| 奇米在线视频了,奇米影音先锋在线播放,奇米国产视频在线观看,奇米影视在线大香蕉| 奇米网在线观看视频不用播放器,奇米影视四色在线视频,奇米网狠狠色很很鲁在线视频,奇米影视4色在线| 奇米米奇777在线四色,奇米米奇影视在线视频,奇米在线线观看视频,奇米在线影视无播放器| k频道如何购买会员,k频道最新视频址,k频道国产网,k频道 最近更新| 奇米弟四色777在线视频,奇米色奇米先锋在线,奇米第四琪琪在线,奇米影视影音先锋在线| k频道网址导航入入口,k频道站3入口,k频道网络分享系统,手机k频道福利| 日本热码AV在线中文字幕,韩日毛片 日韩无码 中文字幕,男人的天堂片,巨乳无码在线| k频道网络视频在线882,k频道网络视频直播,k频道网址导航 最新首页,k频道福利下载| 777奇米,米奇影院第四色,777奇米影视四色,333qqqq电影网| 777奇米在线影院,奇米影院影音在线,色奇米在线,奇米影视在线免费观看| 青青青视频手机在线18年观看,青青视频,青青青在线播放2019,青青青爽在线视频观看| 奇米影院在线播放,奇米网在线免费视频,奇米小说观看在线,奇米影视播放在线| 最新的黄色网站,黄色成人网站,日本的黄色网站,欧美的性爱网站,免费的黄色网站,成人动漫网,黃色录像一级的| k频道网红在线视频,k频道国产精品在线,k频道国内主播,k频道公告网址导航| 777米奇影院在线狠狠色,奇米在线观看姐姐骚,奇米在线资源站,奇米影视777奇米在线影院| 奇米影视在线777免费播放,奇米影影视在线视频3,8888奇米在线,奇米网在线555| 奇米在线777,奇米四色在线观看,伊人在线5 奇米,奇米影视第四在线| 奇米网在线免费播放,奇米啪啪啪在线,奇米影视四色在线影院,奇米四色手机在线无需播放器| 天天色官网,日本熟女在线,任你懆视频 这里只有精品,365天天色综合,俄罗斯一级av大片在级,亚洲在线成色综合网站| k频道最新视频播放,国产糟品k频道网络视频分享系统,k频道为什么下不了,国产视频k频道一本| 奇米在线无码免费视频,奇米小说在线影院,奇米888视在线,在线奇米影视| k频道网络网址导航,k频道国产视频,k频道网址在线导航入口,k频道kpd33导航| k频道网址导航入入口,k频道站3入口,k频道网络分享系统,手机k频道福利| 他也撸影院,他也撸在线影院,大家撸才是真的撸,一个可以撸管的在线影院,老司机带你飞,老司机在线| 奇米米奇影影视先锋在线视频,奇米影院777在线儿视频,奇米琪琪在线,奇米网在线观看555| 8k频道宅男影院,k频道在线k频道福利,彩虹K频道手机在线直播,k网站频道| 奇米影视在线香蕉视频,奇米影视在线免费播放,奇米视频在线看,8888米奇四色在线| k频道在线播放国产,k频道在线直播观看,k频道宅男影yuan,k频道╠娱乐网址导航| 亚洲 欧美 中文 日韩aV 能免费看Av的网,欧美在线,国产情侣av偷拍视频,超碰免费视频| 热同性恋乱伦的影片,网红自拍av,亚洲成在人线视频天堂,av亚洲欧洲无码在线,家庭乱伦电影天堂,久久爱在线欧美| 昆明k6频道在线观看,k频道最新地址获得,k频道sina,kpd la k频道| 奇米网视频在线观看,奇米网在线兔费视频,奇米777四色在线观看,777米奇影在线伦理免费| 亚洲 色 图 成 人 小说,性感美女诱惑图片,超高清诱惑美女写真套图,丝袜美女的诱惑,日韩三级片,国产三级片| k频道在线精品视频道x,k频道kpd02,k频道入口2,最新视频k频道网络分| 最新福利天堂视频,怡红院在线观看手机版,影音先锋 AV 爱色影,日本熟妇人妻videos,天堂va欧美ⅴa亚洲va| 奇米影视先锋在线,奇米影视777在线影院,奇米影视777在线看,奇米网在线中文字幕| k频道视频导航最新2,k频道国产精品cn,昆明k6频道节目表,k频道撸撸色| k频道导航大全的网,k频道宅男影院,k频道网络视频共享系统日韩剧情,k频道在线网址导航网址在线入口| 奇米888在线观看,777奇米在线,奇米在线77me,奇米视频高清在线| 亚洲成人快播,学生妹人人摸碰,爱福利视频广场,插嫩嫩学生妹p,大香蕉天天透啪,欧美做愛坉片,美国成人视频|