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Issue 104 web.pmd

1. Choppers Shielding screening the power converter s output cable Keith Armstrong The EMC Journal Issue 100 May 2012 pages 32 38 available from the archives at www theemcjournal com 99 EMC Design of High Frequency Power Switchers and Choppers Suppressing RF noise in DC inputs outputs and DC Links Keith Armstrong The EMC Journal Issue 101 July 2012 pages 30 38 available from the archives at www theemcjournal com 108 EMC Design of High Frequency Power Switchers and Choppers More PCB issues plus high performance filtering Keith Armstrong The EMC Journal Issue 103 November 2012 pages 27 34 available from the archives at www theemcjournal com 109 EPRI Trouble Shooting Guide for Low Voltage ASD Motor Systems TR 11097 final report November 1998 free download http mydocs epri com docs public TR 111097 pdf 110 Banana Skin number 618 Not using mains filters to save cost cost US 54 million Banana Skins are a regular column in the EMC Journal and can be read current issue plus archives at www theemcjournal com 111 Webinar Cost Effective EMC Design by Working With the Laws of Physics Keith Armstrong November 27 2012 www interferencetechnology com watch our webinar on cost effective emc design by working with the laws of physics 112 The Ground Myth Dr Bruce Archambeault Ph D IBM Distinguished Engineer FIEEE 18 Nov
2. EMC EMI specialists signal integrity specialists technicians printed wiring layout professionals applications engineers PCB design engineers system designers test engineers and anyone who works with digital logic at high speeds 2OMHz to 20GHz and beyond 8 CST European User Conference The 8 CST European User Conference will be held in Stuttgart Germany April 23 25 2013 This conference offers you a great opportunity to advance your simulation skills and exchange ideas with other users More information about this event including the preliminary agenda and online registration is available at www cst com euc Call for Contributions We are interested in your work with the CST STUDIO SUITE product family If you would like to contribute to this event share your experience and discuss your questions in a forum of your peers please submit a text abstract of between 100 and 200 words to events cst com CST honors your contribution to the EUC by offering a discount of 50 on the attendance fee for an accepted presentation Please note that in order to qualify for this discount the final abstract has to be received by 28 02 2013 and the finished presentation by 31 03 2013 EMC China 2013 23 25 October EMC China 2013 will be held from 23 25 October 2013 at Shanghai Everbright Convention amp Exhibition Center www emcexpo com June 2013 High Speed Digital Design 17 18 June 2013 Advanced High Speed Signal P
3. 72 In practice it is easy for such installations to suffer from the accidental addition of earth ground bonds over their operational lifetimes defeating this inductor and potentially causing interference problems to suddenly start to occur for no obvious reason Such installations need careful maintenance To ensure that there are no other earth ground connections some designs of power converters will need their chassis frames enclosures etc galvanically isolating from their support metalwork and other local metalwork including the shields of The EMC Journal January 2013 any cables connecting to them causing problems for cable shielding effectiveness Isolated power converter chassis frames enclosures etc should be made touchproof for safety reasons The mains power distribution network single phase shown for simplicity Either add series inductors in all mains power phases and in series with the neutral if one is used as here effective in reducing the frequencies of both DM and CM series resonances and or add a lower power series inductor in the single dedicated earth ground connection only effective in reducing CM series resonant frequencies but not DM Figure 7 12 4 Using series inductors instead of a mains isolating transformer Even where series inductors and or shunt capacitors have been added to successfully reduce the series resonant frequencies to below the noise sp
4. LF isolating transformers can provide valuable benefits for EMC that are not available from HF isolating transformers So although they are large heavy and costly components especially because of the high price of copper these days they can sometimes be the lowest cost EMC mitigation solution To help achieve cost effectiveness in our EMC work see 11 12 and section 1 4 of 13 we should therefore ensure that LF isolating transformers are considered early in the design process along with all the other EMC design and mitigation issues Later in this Section I give an example of the many very costly incidents that have been caused by leaving EMC design issues to the end of a project In section 7 3 in 72 and later I showed how a power converter s DM and CM noise currents were steered by the capacitors and inductors in its input and output filters and by their low impedance bonding to the power converter s chassis frame enclosure etc which is designed to provide a low impedance over the frequency range to be controlled by the filters The result of this noise current steering is that they flow mostly in the power converter s assembly with so little DM and CM noise current flowing outside of the converter that the limits for conducted noise emissions are met and also to help comply with the limits for radiated noise emissions by reducing the noise that is radiated from any cables Where an AC mains pow
5. Ohms g mae MHz Figure 4 Self resonant frequencies for different capacitor values Any two terminal capacitor will show a minimum impedance at self resonance Figure 4 This is given by 1 2n VLC where C is the actual capacitance and L is the combined inductance of the package and the vias pads and tracks which connect to it Above this frequency it s not its capacitance value but its self inductance which determines the performance Figure 4 shows the impedance of several values of capacitors From this it s clear that for values above around 100nF and frequencies above 10MHz the impedance and hence loss of circuit effect is rising with frequency due to inductance Decoupling Digital decoupling applications are normally most important in the VHF range and above where clock harmonics on the power rails can cause high levels of emissions or where incoming RF or transient interference can create undesirable disturbances Decoupling local to each IC prevents this noise from circulating widely in the power distribution network but practical components are acting as inductors in this region so the actual capacitance value is less critical than the inductance Package size and shape and PCB layout are the most important parameters the capacitance must simply be large enough to keep the impedance at self resonance low A secondary reason from the EMC perspective for decoupling is to prevent significant voltage ripple
6. actual earth ground electrodes for safety reasons should be called electrical Bonding Networks or BNs or electrical Common Bonding Networks or CBNs as per the terminology in IEC 61000 5 2 which is concerned with good practices in cabling and earthing grounding No electronic DC power rails such as zero volt rails OVs should ever be called earth or ground rails and nothing should ever be said to be at earth or ground potential No circuit diagrams should ever use the words Earth or Ground or their related symbols unless they really do mean an actual metal rod that is stuck a few metres into the soil or the marine equivalent Serious problems caused by the confusion arising from the jargon use of the words Earth or Ground have been well known for decades especially in system circuit and EMC design Figure 7 13 1 is copied from slide 42 of 112 and I have seen its creator Dr Bruce Archambeault of IBM use it many times in similar presentations and articles in earlier years amore BEHAL Gawea oe Fp reese gt aoe A aout 3 aisle cash Hour THa TG phe ne G E Afiuhp He z i PUTER T UHA GUNE T r a ae oe mTOR CAJE Ferur fou Go CHA sits GPa Grom gt eee D Ger C gt Er oe yw y GF seeme EEE ee 4teuveo wrae A non A 2 stone Showa os p an DIVORCE Ad s kee QReusp gneve D Gi l orma RFqipanp Ee JANHD n F iki 2 JEI l Faezan CEET T Stevmry From Slide 42 of The Ground Myth
7. 2011 LED Lighting Products by the EMC Administrative Co operation Working Group which can be downloaded from http ec europa eu enterprise sectors electrical files emc ms campaign fourth_en pdf Also of interest are www youtube com watch v FNIM JXUPc and www emcrules com 2011 07 radio interference from led lighting html Dinex Lighting reckon that their LED lighting has Zero EMI emissions www ioonline net ioonlinetest dinexlighting aspx presumably because their luminaires are simply strings of LEDs requiring external power control that will create EMI emissions The problem of emissions above 30MHz from modern lighting technologies was somewhat anticipated by http www ofcom org uk static archive ra topics research topics emc 8056cr2 pdf 53 Only 50 of consumer electronics sold in the EU complied with the EMC Directive in 2009 10 A total of 159 products were evaluated 49 LCD televisions 8 Plasma televisions 39 Blu Ray players and 63 DVD players Overall technical compliance with the requirements of the harmonised standards was low at 50 For emissions only 72 were compliant and for immunity only 69 were compliant There were wide variations in the level of compliance between products Declarations of Conformity DoC were obtainable for only 81 of products Of these only 80 were correct with 15 containing major deficiencies 15 Compliance rates differed widely between tested product
8. Bruce Archambeault Ph D IBM Distinguished Engineer FIEEE 18 November 2008 https ewh ieee org r6 phoenix phoenixeme PCB Design pdf Figure 7 13 1 Some of the many types of symbols for different grounds humorous Regular readers of this series might remember Figure 7 2 4 in Section 7 2 of 72 where I first introduced the concept of noise current diversion by working with the laws of Physics which make noise currents prefer to flow in the loops with the lowest overall impedances that cause the least emissions Well I have duplicated Figure 7 2 4 as Figure 7 13 2 so that you don t have to look it up Figure 7 13 2 shows the typical way we use input and output filters and RF bond local metal structures to use them as RF References to help divert noise currents generated in the power converter s devices so that they prefer to flow in small low Z local loops and not in the mains power distribution network harmonics ASE A P 9 So iz iki Figure 7 13 2 Example VSD fitted with filters and RF bonded to an RF Reference These two figures 7 2 4 and 7 13 2 use the local metal structures as the RF Reference simply for reasons of saving cost by using existing metal structures for EMC purposes Converters that contain their input filters LF rectifiers DC Links output switchers choppers and any LF or HF isolation transformers HF rectifiers output filters etc within a single
9. Radio and Moyne Shire Council over the location of radio masts Mr Howard who lost a Victorian Civil Administrative Tribunal VCAT appeal on the matter has been granted leave to appeal to the Supreme Court of Victoria Two Ace Radio transmission masts on a property opposite Mr Howard s house on Blighs Road were built 126 metres and 58 metres closer to his house than the original planning permit specified The towers are also 11 metres taller than the original specification and have 15 guy wires instead of eight Permission to vary the position was given verbally by a Moyne Shire officer Ace Radio which owns Coast FM and 882 3YB and Moyne Shire Council are named as respondents in the case due to be heard in May Mr Howard has a document from the Minister for Planning Justin Madden that says Changes to a planning permit can not be verbally approved under Victorian planning legislation The permit was retrospectively amended on June 16 this year after the towers had been built following a review by VCAT Mr Howard said the towers were causing interference with his telephone fax computer and radio as well as affecting his animals The revised siting of the masts put them closer to power lines that connect to Mr Howard s house which he believed to be a factor in the interference Independent testing commissioned by Ace Radio and carried out by EMC Technologies showed electromagnetic interference was occurring in the hou
10. and costly high power UPSs to power their entire production line only to find that the UPSs were less reliable than the raw mains supply they had been using We must remember to always ask for trustable evidential proof The EMC Journal January 2013 of any every specification or feature that we need from anything that we purchase and never make assumptions no matter which supplier we deal with 7 13 Noise suppression with floating power networks or floating electronics 7 13 1 Converters powered from floating AC power networks insulated neutrals Ships and other vessels generally use mains supplies that do not have the neutral of their mains power supply directly bonded to their earth ground structure see 60 and some land based installations also use this practice This is known as an IT power network nothing to do with Information Technology and is often described as a floating mains supply It is a common mistake that even appears in some standards for example EN IEC 61800 3 to assume that mains filters require a connection to an earth ground and so cannot be used with floating mains power networks A safety technique used with earthed grounded mains power network is that they open fuses or circuit breakers to remove electrical power from a circuit that has suffered from an insulation fault However in some especially aggressive environments such as marine insulation faults are quite commo
11. as line reactors which are often used to decrease the mains harmonic emissions from power converters These series inductors were mentioned in Section 7 2 and shown on Figures 7 2 3 and 7 2 4 in 72 and will be discussed in more detail in the future section on suppressing mains harmonic emissions In this situation they are used to reduce the frequencies of any resonance with network CM capacitances until they are so low that they are well below the lowest frequency emitted by the power converter and so do not influence its emissions But all series chokes reduce the mains power supply voltage to some degree which can reduce the power available from the converter can make it too inefficient by wasting more heat and also might cause an increased rate of undervoltage tripping due to sags or dips in the supply An alternative to large heavy costly high power line reactors is to fit a series inductor in the earth ground connection to the power converter This appears in series with the CM current and so has the desired effect of reducing CM resonant frequencies but of course it does not have to carry the converter electrical power so can be smaller lighter and cost less Earth ground inductors can only work when fitted in series with the one single conductor connecting the power converter s chassis frame enclosure etc to the earth ground structure of the site or vessel as shown in Figure 7 12 4 also see Figure 7 3 7 in
12. become popular Blocking the 3G signal shuts down the devices but it s hardly a sensible solution as it aggravates commuters However shifting to a licensed band will be expensive both in terms of the equipment it will require and the frequencies in which it can operate Links http english caijing com cn 2012 11 20 112296950 html www scmp com news china article 1084297 shenzhen metro shuts 3g service day after trains inexplicably stop Taken from Pocket Wi Fi hotspots paralyse Chinese metro lines Using free band to run trains oddly didn t turn out well By Bill Ray in The Register http www theregister co uk 2012 11 21 wi_fi_knockout goback 2 Egde_3828357_member_188377735 also at www theregister co uk 2012 11 21 wi_fi_knockout and very kindly sent in by both Les McCormack and Chris Zombolas Another link is http tinyurl com bwag9 96 50 High Power Microwave Missile Disables Computer Systems in Boeing Test Aerospace company Boeing has successfully completed initial testing on a non explosive missile that emits high powered microwaves to disable computer and electrical systems The Counter Electronics High Power Advanced Missile Project CHAMP was tested at the Utah Test and Training Range by members of Boeing Phantom Works the U S Air Force Research Laboratory and Raytheon Ktech In the initial test CHAMP was fired at a two story building built on the test range and emitted a
13. by the use of Institutional Review Boards IRBs Makers of both these devices appear to have hired private companies of medical professionals IRBs to evaluate their devices and to qualify them for use on patients Examination by an IRB is not the equivalent of FDA approval but can be used by the unscrupulous to defraud the gullible or desperate View the entire Congressional letter online Taken from FDA Congressional Sub Committee Take Action Against Alternative Energy Medicine Devices Interference Technology eNews December 27 2007 www interference technology com For more information also see Congress Asked to Investigate Quack Devices Device Watch www devicewatch org reg inslee pdf http en wikipedia org wiki List_of_topics_characterized_as_ pseudoscience http www camlaw blog com promo speaking legal boundaries and ethics in energy work G4 Radio Mast EMI Case Headed to Court A farmer in Purnim a township in Victoria Australia is on his way to the Supreme Court in his battle against broadcasting company Ace Radio over the location of transmission masts Independent testing carried out by EMC Technologies showed electromagnetic interference was occurring in the house and the farmer claims the radio towers are interfering with his telephone fax computer and radio and affecting his animals PURNIM farmer John Howard is on his way to the Supreme Court in his battle against Ace
14. covered by IEC 62271 from the Scope and separation of the requirements for power stations from those for substations IEC 61000 6 1 and 2 These are the IEC Generic immunity standards and enough National Committees support the need for maintenance for it to go ahead but the response was surprisingly small 8 countries out of 38 It may be that few products are now assessed under the Generic standards because applicable product or product family standards exist IEC TR 61000 2 5 This is about the classification of electromagnetic environments and is of importance not only for regulatory EMC where products must cope with the environments in which they are intended to be used but also for the far more difficult subject of EMC and functional safety where the conventional concept of meeting prescribed immunity levels breaks down and must be replaced by risk assessment The EMC environment changes with time maybe more dramatically than would be prudent Power Line Communication PLC and the consequences of the Digital Dividend spring to mind The proposed maintenance will more thoroughly address the power frequency characteristics of environments due to changes induced by PLC and embedded generation IEC 61000 4 11 This standard deals with voltage dips short interruptions and voltage variations immunity tests The responsible committee has put forward a number of proposals to simplify the standard and make its provision
15. energy store Like the DC Link suppression capacitors discussed in Section 7 6 in 99 the lower their shunt impedance at the frequencies of interest the better their DM noise suppression It may be necessary to parallel a number of different technologies for e g batteries supercapacitors and high value metallised film capacitors to achieve the required DM suppression across the whole frequency range of converter noise Continuous on line double conversion isolating UPSs are generally effective at low frequencies say up to 100kHz but models with higher frequency specifications are available and I have seen some UPS products that specified no less than 80dB attenuation for both DM and CM noise at all frequencies from DC to 1GHz Obviously we pay extra for such specifications and most commodity UPSs do not even include noise attenuation specifications in their data sheets so we should always assume such performance to be quite poor until we have seen independent evidence that proves otherwise It is important to beware that some M G Sets and UPS s generate so much noise they make EMC worse overall or create poor power quality e g by emitting excessive harmonic or inter harmonic waveform distortions or are too unreliable Someone who worked at a 24 7 365 continuous steel strip production mill once told me that after losing costly production due to mains interruptions and outages they installed very large powerful
16. guidelines intended to improve consistency between standards some of which have just grown over many years without a sideways look at other standards The proposed guidelines are motherhood and apple pie so can hardly attract much negative comment but the first draft has already been revised The devil is likely to be in the detail so until actual implementation is attempted any potential difficulties may remain hidden CISPR D A New Work proposal has been issued on the measurement of emissions from vehicles boats and internal combustion engines below 30 MHz This refers to both magnetic and electric field emissions but it is far from clear how reproducible results can be obtained for electric field emissions CISPR F Interpretation sheets Two Interpretation Sheets are in process one on retrofit extra low voltage LED lamps and one on wall dimmers CISPR H Although it was expected that this sub committee would be disbanded because the Secretary had retired and no new candidate was forthcoming at the last moment China and Korea offered candidates It was decided to accept the offer from Korea CISPR I VHF LISN CISPR I has been looking at ways of improving the reproducibility of emission measurements and has experimented with adding a LISN Line Impedance Stabilizing Network to each cable exiting the EUT Equipment Under Test This LISN has to work at frequencies above the range of the existing LISN specif
17. is content that they especially wish to hear Similarly listeners will listen to fieldstrengths well below the international limits even if the result is audio which is covered in static and noise For this reason the area in which listeners expect to be able to receive AM at night is almost the same as the area in which they can receive it during the day and is very much bigger than the technical limit of AM coverage Third the failure mode of DRM is as with all digital systems dramatic The transition from working perfectly to not working at all is fairly sudden even considering that DRM 1s designed to provide a measure of graceful degradation for longer than some other digital systems Thus listeners who previously received a degraded interfered with AM service at night now received nothing At other times given the dramatic fluctuation in interfering signal strength listeners found the radio services dropping out or burbling or becoming metallic in sound and taking some while to restore despite any actions they took Taken from Interference Stymies Radio Test in Interference Technology Magazines on line newsletter http 72 29 76 194 interfer interference stymies radio test 05 27 09 04 36 PM and from http downloads bbc co uk devon pdfs project mayflower summary report pdf 2 James C Klouda RFI expert Jim it will be recalled recognized at a very early stage the need fo
18. it is bound to end up co incident with a converter noise emission frequency but only when it causes us the greatest possible trouble cost and embarrassment Increasing the line ground capacitance is a rather obvious thing to do so I won t say any more about it here other than to mention that the capacitors used should be appropriately Y rated for safety reasons and should cope with the ripple current from the AC supply and its harmonic and inter harmonic waveform distortions which can be up to 30 in some offshore platforms see 54 plus the noise voltages created by the emissions from electronic equipment for the anticipated operational lifetime despite their worst case exposure to the physical and climatic environment shock vibration humidity temperature etc and reasonably foreseeable lapses in maintenance If you think I m being a bit alarmist about the importance of ensuring the high reliability of capacitors fitted to a mains distribution network please read 113 This reference is to a case study of the catastrophic failure of power factor correction capacitors on board the Queen Mary that left that vessel with thousands of passengers and crew on board in the pitch dark and without any electrical power drifting entirely at the mercy of ocean tides currents and winds for about an hour We can increase the inductance of the power converter s mains input by adding series inductors commonly known
19. local and remote control of the amplifier The display provides operational presentation of Forward Power and Reflected Power plus control status and reports of internal amplifier status Special features include a gain control forward RF sample port and a reflective RF sample port for precise power measurements Tel 44 0 1908 282766 aruksales arworld us www arukltd co uk em CI A Member New comprehensive catalogue from Kemtron Th Kemtron the leading UK manufacturer of RFI EMI shielding solutions has published a comprehensive new catalogue in response to customer demand The 144 page printed catalogue has proved popular with customers who have limited Internet access or who prefer the convenience of a paper version that they can bookmark add notes or use as a working reference tool Managing director David Wall said We have had a fantastic response from customers in countries like Germany India and Turkey as well as the UK They welcome the fact that they can have a printed catalogue when so many suppliers only offer information on the Web The catalogue provides detailed product overviews technical specifications application informa tion and design considerations for Kemtron s range of RFI EMI shielding solutions as well as background information on EMC and useful design tools Optical Coax eme 7 When copper can perform EMI issues Sentinel and point2point fibre optic link
20. memory cards this week released a fix to an issue that kept their cards from working fully with the Nikon D800 and D800E The problem according to an Eye Fi representative is caused by noise coming from inside the camera specifically from the D800 s unique new USB 3 connector Posted on Monday the update works around the issue by changing the card s broadcast channel Eye Fi s Direct Mode allows a direct connection to devices that can t create a Wi Fi hotspot Early last month reports surfaced of an issue with Eye Fi s WiFi connected SD cards when used in the full frame Nikon D800 and D800E digital SLRs Although the two products were said by their makers to be compatible users found themselves unable to use Eye Fi s Direct Mode and in some cases to use any of the card s Wi Fi capabilities at all Now Eye Fi has issued a fix and a statement from Eye Fi co founder Ziv Gillat published by The Phoblographer suggests that radio frequency interference from the D800 body is to blame By default said Gillat Direct Mode broadcasts on channel six In the D800 due to noise that s coming from the USB 3 interface we needed to broadcast on channel 11 Nikon s D800 is the first DSLR with USB 3 0 connectivity but Eye Fi has discovered that it can interfere with the default channel used by its Wi Fi connected flash cards Although the problem prevented use of Direct Mode with the D800 and D800
21. more representative of the real world This initiative is welcomed and should be encouraged CISPR 11 It is intended to make a thorough revision of CISPR 11 and a simplification of the requirements for emissions above GHz will be treated as a separate project CISPR 13 20 22 and 24 These are still being amended out of necessity to cope with new developments but CISPR has decided to withdraw CISPR 13 and 22 on 2017 03 05 5 March 2017 This clear the way for CENELEC to agree to withdraw EN 55013 and EN 55022 CISPR 15 The FID for the 8th edition has been delayed Meanwhile new proposed improvements are being lined up for future changes Two Interpretation Sheets have been produced and further work is expected on emissions from LED lamps and associated equipment CISPR 32 EN 55032 Maintenance to create a second edition of CISPR 32 has begun with the extremely optimistic schedule CD 2013 01 CDV 2014 01 FDIS 2015 01 The danger is that the quality of the text might be sacrificed in the quest for speed so that there would be continual doubt about what the standard actually means In addition it seems that there is one CD which in fact has already appeared but five CDVs which will be presented separately at the CDV stage and then combined The CD describes clauses of the standard as sections More revision work is expected in 2013 Other developments Consistency of approach CISPR is seeking to adopt clear
22. so this may be a temporary effect New Section of IEC 61000 4 It is proposed to produce a new Basic EMC standard Electromagnetic Compatibility EMC Part 4 XX Testing and measurement techniques radiated fields in close proximity immunity test applicable to the immunity of equipment to radiated electromagnetic energy coming from intentional radio frequency RF transmitters e g mobile phones used in close proximity to other equipment The frequency range covered is to be 9 kHz to 6 GHz The need to develop a basic standard is because this topic needs to be addressed as a horizontal standard by rather than in product standards which would very likely differ undesirably Reconfirmation of IEC 61000 3 11 The maintenance committee has found no reason to update this standard and recommends reconfirmation presumably for five years EMC classes A and B The attempt by CISPR to clarify the definitions of these classes has failed because of established inconsistencies of use that preclude clarification However it seems to me that definitions that I have proposed in previous Columns could be used in future without being applied retroactively At least they could be a guide for newcomers to EMC Trend It seems that the EMC scene is not getting simpler as it appeared to be a few years ago largely due to the rapid development of new technologies So there should be ample material to review in the coming year J M
23. the morning was quiet and I almost felt guilty for invoicing them for that time Almost I was just glad I pursued the shielding question Taken from Chapter Chatter by Todd Robinson Associate Editor EEE Electromagnetic compatibility magazine Volume I Quarter 3 2012 page 8 http ieeexplore ieee org stamp stamp jsp arnumber 06347045 G4 Nikon D800 Wireless Memory Card Issues Caused By RF Interference Eye Fi the manufacturer of SD memory cards and SDHC cards with Wi Fi has released a solution to an issue that prevented their cards from working with the Nikon D800 and D800E In early October Eye Fi confirmed a compatibility issue that impacted the use of Direct Mode in the Nikon D800 Though the two products were marketed as compatible consumers were unable to use Eye Fi s Direct Mode and in some cases unable to use any of the card s Wi Fi capabilities as all According to an Eye Fi representative the company determined the issue was caused by interference emanating from the unique USB 3 connector inside the camera The update provided by Eye Fi changes the card s broadcast channel to prevent further interference issues By default Direct Mode broadcasts on channel six In the D800 due to noise that s coming from the USB 3 interface we needed to broadcast on channel 11 Ziv Gillat Eye Fi co founder said More details from Imaging Resource Makers of the Eye Fi wireless
24. thing of the past particularly because there is always a desire to have the maximum capacitance in the smallest size Greater than 90 loss of capacitance at rated voltage is not uncommon in the general market place But this can be avoided for some parts by specifying 2C1 BZ or 2X1 BX dielectrics rather than standard commercial X7R 2R1 These options have a more tightly controlled VCC at the expense of absolute capacitance value in a given package see Figure 1 again although observe that a worst case capacitance drop of 25 30 is still to be expected Safety issues VCC is not just a problem with respect to circuit functionality there can be legislative implications for certain equipment even if you fully understand VCC EN 61010 1 2010 Safety requirements for electrical equipment for measurement control and laboratory use advises that for voltages up to 15kV equipment is considered hazardous live if it can discharge gt 45uC and 2mA For above 15kV the same applies for energy levels gt 350mJ If we consider a hypothetical high voltage laboratory power supply of 8kV with an accessible capacitive circuit then the 45uC rule restricts us to 5 6nF at 8k V Figure 3 Let s assume the circuit in question requires a minimum of 2nF to function correctly we know there will be some instability in the capacitor so we specify 5 x 3640 10kV InF parts Unfortunately the capacitors turn out to lose 75 of their value under 8kV so we end u
25. to fix a low frequency conducted emissions problem was a new offshore gas drilling rig which cost US 500 million to build It suffered from two separate EMC problems one of which caused its large and powerful cranes to go out of control causing very real safety hazards After four months without drilling and a great deal of lost production a power quality expert was called in who quickly fixed the safety problem by installing a IMW isolating transformer After both issues were resolved the manufacturers of the rig counted the real costs of the EMC problems which exceeded US 54m Figure 7 12 5 shows the noise generated by the worst of the 700kW 3 phase drives fitted to its cranes before and after fitting the 1MW isolating transformer to that crane drive OH Figure 7 12 5 Example waveforms from a generator with a 700kW 3kHz AC motor drive load Marine vessels and offshore platforms aircraft non electric trains and road vehicles all have the problem that their AC power supplies come from generators which have between three and five times the source impedance of an onshore high voltage grid connected transformer having the same power rating So the non linear currents that electronic equipment draws from mobile AC power supplies generally causes three to five times the level of DM voltage disturbances that they would when powered from the AC mains power in a fixed installation on land But this problem was caused by CM cu
26. to increase the apparent CM impedance of the AC mains power supply to help to discourage CM noise currents emitted by the power converter from flowing in the mains supply network But we have a problem at lower frequencies where CM chokes behave inductively rather than resistively see Section 5 2 6 in 5 because their inductance can series resonate with the CM capacitance that naturally arises in the mains distribution The EMC Journal January 2013 network the stray capacitance between mains cables and earth ground structures Series resonant current loops have very small impedances just the resistance of their conductors Because the CM capacitors in the mains filter have relatively high impedances at low frequencies most of the CM noise current can end up flowing in part of the supply distribution network possibly causing interference instead of circulating locally as we want Also if the mains filters fitted to other equipment connected to the same mains supply have capacitive CM inputs instead of the inductive resistive inputs provided by series CM chokes such as used in Figure 7 12 1 this extra capacitance can add to the distribution network cables capacitances to create lower resonant frequencies So we can see that in real applications mains filters can be significantly less effective at certain frequencies than EMC laboratory tests would imply and can even amplify noise emissions rather than suppress them T
27. 112 resulting in a loss of occupant survival space in the lead car of about 63 feet about 84 percent of its total length Nine people aboard train 112 including the train operator were killed Emergency response agencies reported transporting 52 people to local hospitals Damage to train equipment was estimated to be 12 million Investigation Synopsis The National Transportation Safety Board s investigation found that the Metrorail automatic train control system stopped detecting the presence of train 214 the struck train which caused train 214 to stop and also allowed speed commands to be transmitted to train 112 the striking train until the collision This loss of detection occurred because parasitic oscillation in the General Railway Signal Company GRS Alstom Signaling Inc Alstom track circuit modules was creating a spurious signal that mimicked a valid track circuit signal thus causing the track circuit to fail to detect the presence of train 214 The investigation found that the track circuit modules did not function safely as part of a fail safe train control system because GRS Alstom did not provide a maintenance plan that would detect anomalies in the track circuit signal such as parasitic oscillation over the modules service life and prevent these anomalies from being The EMC Journal January 2013 interpreted as valid track circuit signals The investigation examined two near collisions in 2005 nea
28. 7 This Report complements IEC TR 61000 3 6 in dealing with voltage fluctuations due to loads on MV HV and EHV systems It is of course advisory IEC 61000 3 8 This standard specifies emission levels frequency bands and disturbance levels for mains signalling ripple control which is mainly used by electricity suppliers not in Britain but extensively elsewhere There are three frequency bands defined for use in Europe 3 kHz to 9 kHz 9 kHz to 95 kHz and 95 kHz to 148 5 kHz The upper band stops just short of the LF long wave broadcast band in Europe Controversy has recently arisen because some countries outside Europe want the bands extended to 500 kHz because they do not have LF broadcasting It isn t clear why different frequency ranges cannot be specified for different continents or ITU Regions IEC 61000 3 9 This was intended to be a standard for emission limits for interharmonics currents at frequencies not related to the power frequency but a controversial alternative approach has been developed measuring harmonic currents with a bandwidth equal to the power frequency so that harmonics and any interharmonics are added together This has been shown to result in equipment that does not cause any problem in practice nevertheless exceeding the limits After a very long discussion over several years a solution to this has appeared which may be adopted during 2013 If so IEC 61000 3 9 will be deleted f
29. 950s high voltage circuit breakers began being manufactured with a guaranteed fault clearing time of two cycles at 60 Hz or less and at a modest premium over three cycle breakers This was a substantial improvement and many were installed But due to the inertia of its moving parts there are finite limits to the operating speed of electro mechanical protective relays So with the invention of the transistor there was an immediate interest in utilizing these static no moving parts components in new designs of transmission line protective relays as they held the promise of saving another full cycle 16 67 milliseconds off the overall operating time of the relay circuit breaker combination Beginning in the late 1950s General Electric and Westinghouse designed and built static terminals whose designs were thoroughly tested on model power system simulators These simulators were vital proof testing tools to examine all varieties of single phase double phase line ground line line and three phase faults at various distances on two and three terminal lines They did operate The EMC Journal January 2013 much faster and were beginning to be widely deployed Then the transistor components in these static terminals began to fail and with no apparent connection to any high current short circuit event at or near the substation What a mystery Even more troubling was the fact that the failures we
30. Association The Trade Association for the EMC Industry Web www emcia org audits to achieve and maintain certification Previously CESG was the only UK organisation able to certify products Now that TUV SUD is one of three accredited testing facilities in the UK authorised to issue TEMPEST Certificates the certification process is faster and more agile Jean Louis Evans Managing Director of TUV SUD Product Service said Our appointment as a TEMPEST Certification Test Facility is testament to TUV SUD s pedigree in TEMPEST and EMC conformance testing The combination of our impartiality familiarity with an extensive range of ICT products experience of working with many governments and NATO as well as our international presence makes our expansion into the TEMPEST certification domain a simple transition The EMC Journal Free to readers worldwide January 2013 Issue No 104 Published every other month First Issue March 1995 Editorial amp Publishing Director Alan E Hutley alan hutley nutwooduk co uk Technical Consultant Dave Fynn alan hutley nutwooduk co uk Advertisement Sales Director Lynne S Rowland lynne theemcjournal co uk About TEMPEST TEMPEST is a general term for naturally occurring and unintentional electromagnetic emanations from equipment and systems which can result in the spatial and conducted recovery of sensitive information from a distance TEMPEST certification is based
31. E bodies there was no risk of data loss images were still written to the flash card even if they could not be transmitted wirelessly Some users have reported more general problems with Wi Fi beyond the Direct Mode though and Eye Fi s fix doesn t specifically address this Nor could problems in other modes be addressed by firmware if the problem is indeed caused by RF interference on specific channels as the channel is set by the access point not the client Of course if you are having problems beyond Direct Mode and have access to the router it would seem logical that configuring it to use channel 11 if too many adjacent networks aren t already using that channel would be likely to help the situation More details on the firmware update can be found on the Eye Fi website Taken from www interference technology com nikon d amp 00 wireless memory card issues caused by rf interference 12 19 2012 and also from Imaging Resource D800 compatibility problems caused by RF interference says Eye Fi by Mike Tomkins posted Wednesday November 21 2012 at 7 31 PM EST www imaging resource com news 2012 11 21 d800 compatibility problems caused by rf interference says eye fi Also of interest is the Nikon Rumors site http nikonrumors com 2012 11 20 eye fi cards now compatible with the nikon d amp 00 camera aspx Survival of the Fittest EMC in Electric Power Substations When a short
32. I was clear on this we went to their 10 engineering laboratory grabbed some overbraid and shielded the signal lines assuring both ends of the shield were well bonded to the connectors Back at the testing laboratory the test engineer and the head engineer from my client s company were both weary after many failures So starting at a low level 100 amperes injected current they slowly worked their way up to the test limit of 150 amperes After passing at 140 amperes the test engineer said Okay are you ready for 150 amperes the full test level We all assured him that we were ready When the test engineer initiated the test we immediately heard a large BANG We watched in stunned disbelief as sparks flew and smoke escaped from each connector My client looked like he was ready to change careers hanging his head in defeat At that point the test engineer turned to me and apologetically said Oops That was 1 550 amperes Now that I knew the reason for the sparks and smoke I turned to the customer engineer and said Wait this may be okay Check the unit Is it still working After a moment he said Yep It s working fine I told the customer engineer that I could get off his payroll at that point since his unit appeared to pass at 10 times the test level But he would have none of that He told me that I was to sit there and watch the rest of the four hours of testing The rest of
33. IG S l Ld E _ ee he l L T A i i ar a an CU oe a p n i ELT roo re AT Eis d pi W ry a a q j i be V L i i 7 72 a ah uf mi als Fat plate i aj i SX un Eiri u hae i a li A ar Miz THE NEW SGIRiz EMC amalhyser Ideal for Self test self certify strategy e 10 KHz 3Ghz e Full or pre compliance testing e Optional pre selector e Optional tracking generator output e Standard limits pre loaded e 200Hz 9KHz 120 KHz amp 1MHz RBW e Realtime display of Pk QP and Ave detectors for up to 20 peaks e Simple output of results to other Windows applications e USB interface A superb EMC test instrument for an affordable price Laplace Instruments Ltd 44 0 1692 40 20 70 www laplaceinstruments com What s In This Issue 5 News and Information 2 Voltage Coefficient of Capacitance By Matt Ellis Syfer Technology and Tim Williams Banana Skins Elmac Services John Woodgate s Column 25 EMC design of high frequency power switchers and choppers The EMC benefits of LF mains isolating Know Your Standards transformers plus noise suppression for floating power networks and floating electronics Product Gallery By Keith Armstrong Cherry Clough Consultants Advertisers Index A we Guts er Clc Za ACADEMY the jou rnal c Compatibility Industry Asso g TS EMC Training for In
34. Issue 104 January 2013 See page 18 See page 8 s 5 pm hi A Fh B th r 1 j a a i a B p i E f S yh Fh BTh E Ss aes p a Oe CIE a r 7 a l 1 F 1 B E j in a A oe N i is i a L l l k E n H fi q p J E ij L J b 47 F a S fas FF O an el ee Go S E i More speed More insight More intelligence The R amp S ESR is the new test receiver for standard compliant EMC testing Save time The R amp S ESR time domain scan makes EMC measurements faster than ever before allowing you to dedicate more time to your main mission 1 Find everything The realtime spectrogram and the persistence mode seamlessly display the spectrum so you can detect and analyze sporadic or hidden emis sions and their cause 1 Work flexibly The R amp S ESR combines a test receiver and full featured spectrum analyzer in a single instrument giving you all the tools you need for your measurement task 1 Simplify measurements The R amp S ESR combines functionality with clear structure for easy navigation on the convenient touchscreen Want to know more Convince yourself visit www rohde schwarz com ad esr Tequency 12 6375000 F E fi r pT fs pet ARE a Fh e D pm i a i i i J d a a l Visz Y Cl 1 E T gt E KS nenn ae EREE EN Ee k Ea rir i rari U
35. January 2013 32 Safety Approved low value capacitor May need several spaced no further apart than 4 10 at fmax Figure 7 13 5 Indirectly RF bonding a floating power converter to its local earth ground Because it only has to provide a low Z path for higher frequency noise currents the capacitor values can be reduced so that they do not compromise the correct operation of the insulation failure detection systems whilst still providing useful RF noise suppression For more detail on suppressing floating power converters with indirect RF bonding capacitors see Section 7 13 2 below bearing in mind that this section is not concerned with floating AC supplies with their insulation failure detection systems When using cable shields armour instead of output filters as discussed in Section 7 5 in 92 capacitive RF bonding could be used for the output cable s shield armour fitted either at the power converter s output or the load s e g a motor terminal box or both Capacitive shield armour RF bonding will not be as effective as a proper 360 shield bonding described in full detail in Section 4 6 in 5 but may be good enough if the lead lengths of their RF bonds are kept very short Such shield armour bonding capacitors should be safety approved and rated for the full phase to phase voltage and the values of the capacitor s used where a floating converter drives an earthed grounded load such as a motor
36. VE 10 700us AC DC DIPS INTERRUPTS and VARIATIONS COMMON MODE and both AC and IMPULSE MAGNETIC FIELDS Covering all international standards IMU3000 combines Surge voltages up to 8k V with EFT up to 6kV to make IMU3000 the automatic choice for manufacturers and test labs Packed with new features IMU3000 is setup simpler and faster A wide range of accessories extend I MU3000 application beyond the ordinary Ethernet interface enables control communication and custom report generation Tel 44 0 1494 444255 sales emcpartner co uk www emcpartner co uk EMCIA Member New RF radiation meter The new NIM series RF radiation meter from Link Microtek has been specifically designed to enable plant managers and safety professionals to take quick and easy measurements of emissions from industrial sources such as RF heat sealers RF induction heaters and semiconductor fabrication equip ment Manufactured by Narda Safety Test Solutions the NIM unit provides a straightforward means of ensuring compliance with the permissible exposure limits laid down in the ICNIRP international standard The battery powered meter features an isotropic dual element probe that simultaneously measures electric and magnetic fields both of which are required for equipment operating below 300MHz Users can toggle between E field and H field readings at the press of a button and the instrument features automatic zeroing at power on and e
37. Woodgate B Sc Eng C Eng MIET MIEEE FAES Email desk nutwooduk co uk Web www jmwa demon co uk J M Woodgate 2013 The EMC Journal January 2013 IEC 61000 3 series As threatened last time we continue our review with Part 3 of IEC 61000 whose Sections include two of the most important EMC standards applying in Europe now and under active consideration no doubt with many changes in the Americas Derived national standards apply in several other countries IEC TR61000 3 1 We start on a low note in 1998 this was supposed to be a Technical Report giving an overview of the whole series It was abandoned in 2011 after zero progress IEC 61000 3 2 This is one of the two controversial emission standards on low frequency conducted disturbances those known to their friends and enemies as mains harmonics It is a product family standard with a huge family and applies to everything that has a household type mains plug or draws up to 16 A per phase OK I know the risks of absolute statements somewhere someone may make a product so abstruse that it would never be used on the public electricity supply so doesn t have to meet this standard It divides products into four classes A to D where Class A applies to most product types Class B applies to mostly hand held power tools used for short periods only Class C applies to lighting equipment which has a complicated definition it imposes s
38. allocated may be very much clearer of interference and so the difference between daytime and nighttime reception will be less marked it is possible that the frequency allocated to BBC Radio Scotland 810 kHz is one such example However a difference between the daytime and nighttime coverage of the transmission will always present a problem even if the nighttime coverage is greater than the claimed AM coverage at the moment This is for three principal reasons First the enormous area which appears to be served by DRM during the day means that the contrast between the nighttime and daytime coverage is even greater and potentially affects even more people Mediumwave transmitters are typically planned on the edges of cities so that the main centre of population is comfortably within the nighttime coverage area of the AM However if DRM is capable of serving a widearea then it stands to reason that neighbouring centres of population previously outside both daytime and nighttime coverage will now be daytime only Second whilst the nighttime coverage of DRM is greater than the equivalent clean AM coverage it is apparent that the technical limit of AM coverage is not the same as the limit at which listeners will stop listening to it Thus listeners will tolerate much more crosstalk from interfering sources than is catered for in international planning standards even The EMC Journal January 2013 more so if it
39. an be managed Techniques for avoiding or reducing the impact of power quality issues are well known and the cost of their deployment relatively easily determined However assessing the potential cost impact of power quality PQ issues is difficult because for example the incidence of problems the response of equipment and the effect on process continuity are statistical in nature and are difficult to quantify Although there have been numerous case studies there has been so far no consensus on how the calculation or assessment of these costs should be approached This report provides a methodology for examining the economic framework for The EMC Journal January 2013 PQ It will enable all interested parties to establish costs and benefits of PQ improvement and mitigation measures in a consistent and open manner Studies in the USA In year 1993 Clemmensen 46 provided the first ever PQ cost estimate for U S manufacturing sector The estimate derived that annual spending on industrial equipment due to PQ problems could sum up to 26 billion dollars for the U S manufacturing sector It was estimated that for every manufacturing sales dollar l 5to 3 US cents 1e L53 390 are spent to mitigate PQ problems A few years later in 1998 Swaminathan and Sen 46 in a Sandia National Laboratory report estimated that U S annual power interruption cost reaches 150 billion This estimate was based on a 1992 Duke Pow
40. arget simulator uses low loss optical fibre to create the distance between the radar and the target there is almost no difference between the amplitude of a close by and far away target reflection To create a more real world simulation the system can be fitted with an optional variable attenuator that varies the level of reflection as a function of the distance New Manager for Chomerics New Business Unit Pentair has formed a new global business unit called Pentair Equipment Protection to bring together its three renowned brands of Schroff McLean and Hoffman This umbrella unites all components systems and service schemes related to the protection and cooling of electronics and electrical assemblies so customers now have a very large range of products know how and services available to them For more than 50 years Schroff has been associated around the world with electronics packaging solutions for test and measurement industrial automation defence transportation and communications systems Products range from cabinets cases The EMC Journal January 2013 and subracks to power supply units backplanes and complete systems for a variety of bus based specifications Similarly McLean has enjoyed a reputation for over 30 years as a source of quality cooling products including fans air conditioners and custom electronics cooling equipment The Hoffman brand is known in the market for enclosure systems providing secu
41. burst of high power microwaves that knocked out rows of personal computers and electrical systems inside the building The television cameras set up to record the test were also disabled CHAMP hit a total of seven targets with high power microwaves over a one hour time period According to Keith Coleman CHAMP program manager for Boeing Phantom Works the successful completion of testing marks a new era in modern day warfare where the technology may be 13 used to disable the enemy s electronic and data systems before any troops or aircraft arrive Boeing hopes that the project will change modern warfare by defeating electronic targets with little or no collateral damage Taken from www interference technology com high power microwave missile disables computer systems in boeing test 10 23 2012 for more info visit www boeing com Features 2012 10 bds_champ_10_22_12 html Nine people killed in train collision 12m damage due to spurious parasitic oscillation Abstract On Monday June 22 2009 about 4 58 p m eastern daylight time inbound Washington Metropolitan Area Transit Authority Metrorail train 112 struck the rear of stopped inbound Metrorail train 214 The accident occurred on aboveground track on the Metrorail Red Line near the Fort Totten station in Washington D C The lead car of train 112 struck the rear car of train 214 causing the rear car of train 214 to telescope into the lead car of train
42. by earthing grounding it had actually improved the local RF Bonding and allowed noise currents to flow in lower impedance more local loops that caused less interference But because of confusion caused by the use of jargon terminology the EMC benefits were mistakenly thought to have somehow had something to do with the earth ground electrode stuck in the soil acting as a sink of some kind which is actually impossible in this universe Ah I feel better now and can get on with the rest of this little article 7 13 2 Isolated converters powered from DC power networks Isolated DC powered electronics are typical of many automotive marine and aircraft applications where the chassis hull fuselage etc of the vehicle is used as the battery return conductor a very bad EMC practice which dates from pre electronic times but seems impossible to get away from The DC supply is connected to the chassis hull fuselage etc but the RF References of electronic units cannot be directly connected to them in case bad connections between metal parts allows large battery currents to flow through the electronics probably causing damage or even a fire The solution that allows the return current paths to flow with the smallest loop areas which is the best for EMC is to RF bond the electronics RF Reference e g its metal chassis frame enclosure PCB OV plane etc to the vehicle s chassis hull fuselage etc using capacitors and their c
43. categories ranging between 20 and 56 Blue ray players available mainly from major companies score significantly better than DVD players large low cost segment both in technical and administrative compliance However there is no similar tendency in the case of Plasma LCD TVs The generally poor results for DVD players and for the immunity of plasma TVs have substantially reduced the overall compliance of all tested categories to 34 Country of origin could not be determined for 11 of the samples Taken from Report on the Joint Cross Border EMC Market Surveillance Campaign 2009 10 on Consumer Entertainment Electronics Products the 3 EMC Market Surveillance Campaign by the EMC Administrative Co operation Working Group which can be downloaded from http ec europa eu enterprise sectors electrical files emc ms campaign third_en pdf 50 EMC Crime It is becoming common worldwide for criminals to jam wireless datacomms in factories bringing production to a halt They only stop jamming when paid to There was a paper on this at Hanover EMC this year Kindly sent in by Dipl Ing Werner Grommes on 14 June 2012 Banana Skins Banana Skins are kindly compiled for us by Keith Armstrong If you have any interesting contributions that you would like included please send them together with the source of the information to keith armstrong cherryclough com Although we use a rather light h
44. circuit occurs in a transmission substation usual definition voltages above 100 000 volts the resulting fault current is spectacular In some substations it may be as high as 80 000 amperes 11 Let s assume the fault was caused by the flashover of a porcelain insulator supporting a section of the high voltage power line a few towers away from the substation due to a buildup of sea salt The protective relays monitoring this transmission line detect this abnormally high current and close their trip contacts which then cause both the high voltage circuit breakers connected to this transmission line to open and thus clear the fault But while the fault exists this high current is flowing from the tower to ground then through the earth back to the substation And since there is a finite non zero resistance to true earth ground this causes the entire substation ground matt voltage to rise However this is a 60 Hertz voltage and adequate insulation in control circuits and electromechanical protective relays for this well recognized ground potential rise has been defined for years in protective relay standards e g ANSI C37 90 It is the time to clear interrupt high fault currents and particularly three phase faults that determine how long a given electric utility or an interconnection of several utilities can remain stable after the fault has cleared In the late 1
45. cking out three times that amount They add that once eight of either kind come into range then the Metro s signalling system stops 2 4GHz is reserved globally for unlicensed ISM Industrial Scientific and Medical use largely because it was considered worthless as it gets absorbed by water and because the band is rife with interference from microwave ovens However radio is a lot cleverer these days and Wi Fi is squeezing every cent out of the spectrum while Bluetooth dances around it and numerous door locks remote controls and other consumer devices fill any gaps which remain Originally it was the unlicensed nature of the band which made it so popular but these days it is also the low cost of the kit International standardisation means a Wi Fi router Bluetooth headset or just a radio chip can be sold anywhere providing massive economies of scale There s also the freedom from regulatory process Set up a link at 5 8GHz and in the UK you ll have to fill in forms and register each transmitter but do the same thing at 2 4GHz and there s zero paperwork making deployment quicker and cheaper The combination of these things drove Shenzhen Metro to connect up its signalling system at 2 4GHz only to discover that it is now polluted with customer connections And Shenzhen is far from alone in its plight as the same band is used by metro systems all over China which will similarly fail once Mi Fi devices
46. d very costly indeed The common mistake of course is to confuse the RF Reference terminal of a mains filter with the earth ground electrode that is stuck a few metres into the soil or the metal hull of a vessel that provides the exact same function by being in direct large area contact with a body of water lying on the surface of our planet e g lakes rivers seas It isn t helped by the fact that most if not all mains filters and many other types too incorrectly identify their RF Reference terminal with the IEC symbol for earth ground and sometimes actually label it as Earth or Ground And most data sheets application notes articles guides and books describe the RF Reference terminal of a mains filter as its Earth or Ground terminal This isn t the only situation in which the confused jargon associated with the terms Earth or Ground in circuit and EMC design has caused costly mistakes which is why in all my articles training courses guidebooks and textbooks I always strongly recommend never using the terms Earth or Ground for anything that is not actually an earth ground electrode metal rod stuck in the soil or its marine equivalent metal hull or structure of a vessel such as a ship or drilling rig o1l gas production platform etc that is in direct large area contact with a river lake or sea All of the conductors and conductive structures that are connected together and usually but not always connected to
47. device with a 15cm range of a pacemaker if possible as your device can interfere with the pacemaker e To minimise possible interference with a pacemaker use your device only on the side of your body that is opposite the pacemaker Do not use your device in a hospital or near medical equipment that can be interfered with by radio frequency If you use medical equipment contact the equipment manufacturer before using your device to determine whether or not the equipment will be affected by radio frequencies emitted by the device If you use a hearing aid contact the manufacturer for information about radio interference The radio frequency emitted by your device may interfere with some hearing aids Before using your device contact the manufacturer to determine whether or not your hearing aid will be affected by radio frequencies emitted by the device Turn off the device in potentially explosive environments Turn off the device in potentially explosive environments instead of removing the battery e Always comply with regulations instructions and signs in potentially explosive environments e Do not use your device at refuelling points petrol stations near fuels or chemicals of in blasting areas The EMC Journal January 2013 e Do not store or carry flammable liquids gases or explosive materials in the same compartment as the device its parts or accessories Turn off your device when on an aircraft You
48. dustry by Industry www theemcjournal com www emcia org www emcuk co uk www emcacademy org Every effort has been made to ensure that the information given in this Journal is accurate but no legal responsibility is accepted for any errors omissions or misleading statements in that information caused by negligence or otherwise and no responsibility is accepted in regard to the standing of any firms companies or individuals mentioned or for any advice or information given by them The EMC Journal January 2013 _AC POWER SPP is Special Waveform z Power Line irregularity ti t Output l Simulation Function he Aw Crest Factor can be set from 1 1 to 1 4 Output Modes AC DC or AC DC Bl ATIII AT Jiii HTT TTIT HHI AC DC IIIT Single phase 500VA to 9kVA AC 1 to 300V 1 to 999 9Hz DC 1 4 to 424V 3 phase option NEW PCR LE Series Fg a 1 eens y 2 www telonic co uk info t elim BS 792 338 TWT Amplifiers from TMD Delivering the Power the power in microwaves for HIRF SSN Complying with RTCA DO 160G Amplifiers achieving up to test criteria to meet the latest and above 10 000 V m with EMC test requirements A Q par Angus antennas Si From 1 40 GHz ON up to 40 kW www tmd co uk 2013 TMD Technologies Ltd News Electromagnetic Testing Services unveil New 3m Semi Anechoic Chamber Electromagnetic Testing Services ETS are pleased to annou
49. e are no more Sections of Part 3 but there might be in future Next time we look at IEC 61000 5 series and perhaps the 61000 6 series as well J M Woodgate B Sc Eng C Eng MIET MIEEE FAES Email desk nutwooduk co uk Web www jmwa demon co uk J M Woodgate 2013 19 REMC A microwave vision company f Total Shielding amp Anechoic Solutions HETT ald f gt e il j sz m j t Ly World class experience in shielded chamber design manufacture installation testing and maintenance 3m compact 3m 5m amp 10m solutions Antenna measurement chambers Emissions amp immunity High performance shielded rooms for EMC Tempest EMPP and MRI Masts turntables amp controllers Mode stir For more information please contact Tel 44 0 1942 296190 www rainfordemc com sales rainfordemc com Touch the future A constantly evolving market needs new ideas and new technologies A graphical user interface with intuitive touch panel that every mobile device user will recognise makes IMU3000 the most popular addition in every EMC laboratory Extend test capability with on site upgrades reduce service costs and increase system availability Users can exchange pre calibrated modules on site to make the most of IMU3000s innovative time and money saving features Have the tester you want Choose from any combination of ESD EFT CWG RINGWA
50. e value some well documented some less so We all know about tolerance and temperature coefficient of capacitance they are clearly defined in dielectric classification codes and part numbering systems Where things become less clearly defined is for VCC or Voltage Coefficient of Capacitance COG NPO CG BP ie temperature range No DC voltage applied Rated DC voltage applied 0 30 ppm C 15 20 15 15 15 20 R 15 30 25 Figure 1 Capacitance change versus temperature and voltage for common ceramic dielectrics The effect of VCC Dielectrics used in MLCC MultiLayer Ceramic Capacitors generally fall into two categories stable and ultra stable or class II and class I Class I are typically COG or NPO these are very stable with temperature and voltage so you get what you asked for but with a relatively low permittivity so you don t get as much capacitance voltage product in a given volume as with other dielectrics Class II are more variable and the lack of definition of VCC is where problems can occur VCC is a function of the properties of the dielectric material and the voltage stress applied typically in volts per micron The effect is negative and non linear becoming asymptotic toward the limit of dielectric strength In effect most of the loss occurs long before the part reaches its operational voltage limit even with de rating there will be significant capacitance loss See f
51. earted approach to draw attention to the column this in no way is intended to trivialise the subject Malfunctions due to incorrect EMC procedures could be life threatening The EMC Journal January 2013 Never a dull moment About 360 new EMC standards documents have been circulated since last time but many are not the stuff of which review articles are made Nevertheless there are enough hot topics to keep us amused CISPR meetings in Thailand CISPR and its sub committees met in November 2012 A very surprising document was submitted to CISPR H committee by ITU It includes a statement that emissions from unintentional radiators should be restricted to a level 20 dB below the receiver thermal noise No mention of distance and no mention of any values of receiver thermal noise There seem to be few unresolved highly controversial issues in CISPR at present It could be a welcome lull before issues related to the actual use of CISPR 32 and or CISPR 35 by people not involved in their development arise Smart grid We are still getting many long documents some with pretty and far too arty graphics but it is difficult to see that real progress is being made No doubt the subject is large and complex but it should emphasize practicalities Maintenance The fact that standards need continual maintenance is often criticized but if they were set in stone it would greatly inhibit the introduction of new better and less c
52. ectrum of the power converter without causing any of the problems mentioned above we still have a resonant power network structure that will amplify any CM noises at its resonant frequencies Noises at these low resonant frequencies might exist in the mains distribution network either emitted by larger power converters due to their lower switching chopping frequencies or caused by lightning surges most of the energy in a lightning stroke is contained in the spectrum below 10kHz or surges caused by electrical faults Generally speaking there is more energy available from continuous and transient noises on power distribution networks at lower frequencies So tuning the network resonances to lower frequencies by increasing the series inductances at a converter s mains or earth ground terminals might well reduce its noise emissions to the supply network but could make the power converter more likely to suffer interference even damage due to the increased levels of noise and or overvoltage surges at the network s resonant frequencies So a less complicated solution with far fewer unwanted side effects is to use a large costly mains isolating transformer dedicated to the power converter and located immediately adjacent to it LF mains isolating transformers can use special design techniques e g increased physical segregation of primary and secondary windings and or adding one or more interwinding shields RF bonded to the loca
53. ember 2008 http ewh ieee org r6 phoenix phoenixemc PCB Design pdf 113 Report on the investigation of the catastrophic failure of a capacitor in the aft harmonic filter room on board RMS Queen Mary 2 while approaching Barcelona 23 September 2010 Marine Accident Investigation Board Very Serious Marine Casualty Report Number 28 2011 December 2011 www maib gov uk cms_resources cfm file QM2Webreport pdf Eur Ing Keith Armstrong CEng FIET SMIEEE ACGI phone fax 44 0 1785 660 247 keith armstrong cherryclough com www cherryclough com The EMC Journal January 2013 Free Information from Advertisers Listed below are the Advertisers in the current issue showing the page number where the company s advertisement appears together with their web address and email AR Europe OBC www ar europe ie info ar europe ie CST UK IBC www cst com emc info uk cst com Instrument Plastics Page 7 www instrumentplastics co uk sales instrumentplastics co uk Kemtron Page 24 www kemtron co uk info kemtron co uk Laplace Instruments Page 3 www laplace co uk tech laplace co uk PPM Page 21 www point2point co uk sales ppm co uk Rainford EMC Systems Page 19 www rainfordemc com sales rainfordemc com Rohde amp Schwarz UK IFC www rohde schwarz com contact uk rohde schwarz com Schurter Page 24 www schurter co uk sales schurter co uk Telonic Page 4 www telonic co uk info telonic co uk TMD Page 4 www tmd co uk wecare tmd c
54. emission frequency but then any variation in capacitance will shift this resonant frequency by VAC with greater than expected results for the emission Conclusions VCC is an important component characteristic which is often overlooked and can cause significant problems in certain applications Voltage de rating running a capacitor significantly below its rated voltage will limit the degree to which capacitance value degrades but this generally involves a trade off with package size The same is true of choosing an ultra stable dielectric such as COG NPO Standard off the shelf components will vary in their performance so it is best to seek the advice of your supplier at the initial design stage to avoid the need for corrective action Matt Ellis is with Syfer Technology Norwich Tim Williams is with Elmac Services Wareham superio www schurter com emc_news standard and custom EMC line filters for 1 and 3 phase systems filters for AC and DC applications various chokes and pulse transformers power stage modules for galvanic isolated control of GBT Drives 6 SCHURTER ELEGTRONIG COMPONENTS wer wos rae The long awaited catalogue WWW co uk 44 0 1376 348115 info kemtron co uk EMC design of high frequency power switchers and choppers The EMC benefits of LF mains isolating transformers plus noise suppression for floating power netw
55. er distribution network feeds two or more items of equipment spread over a site or vessel the DM impedances of the phases can become different from each other due to unequal loading and the CM impedance between the phases and the earth ground which is usually quite high kQ possibly even MQ can become quite low 10s of Q possibly even less due to the stray capacitances of the long cables and the CM filters in other equipment Resonance effects in the mains power distribution can also cause unbalanced DM impedances between its phases and the CM The EMC Journal January 2013 impedances between phases and earth ground can become very low indeed at resonant frequencies Such impedance characteristics associated with a mains power distribution network can degrade the performance of a power converter s mains filter see 109 For example when the CM impedance of the mains supply is low the ratio between the impedance of the local noise loop 1 e the one that is good for EMC achieved by shunt capacitors in the mains filter and the impedance of the external noise current loop in the mains supply the loop that is bad for EMC might not be as high as we would like Figures 7 12 1 and 7 12 2 try to show this problem single phase shown for simplicity RF Reference PCB OV plane chassis frame enclosure vehicle chassis Most DM and CM noise currents flow locally in the low Z Inevitably some o
56. er outage cost survey in the U S that manipulated industrial electricity sales as the basis for the estimate Later in year 2001 EPRI s Consortium for Electric Infrastructure to Support a Digital Society CIEDS 47 produced a report based on a Primen survey in the United States The report identified three sectors of the U S economy that are particularly sensitive to power disturbances e The Digital Economy DE telecommunications data storage and retrieval services biotechnology electronics manufacturing and the financial industry e Continuous Process Manufacturing CPM paper chemicals petroleum rubber and plastic stone clay and glass and primary metals e Fabrication and Essential Services F amp ES all other manufacturing industries plus utilities and transportation facilities Root Causes From 500 EPRI PEAC Investigations Bectromagetic interference 2 Sher 02 Load imersction E ap Sevitching Transients fae Grounding E ia Harmonics iii 2 Voltage fags A Swell ry Ant o i 25 a 40 Be aUh Parcent of Total Breakdown of the power quality found in more than 500 EPRI investigations 14 These three sectors collectively lose 45 7 billion a year due to outages and another 6 7 billion a year due to other PQ phenomena It is estimated that the U S economy losses between 104 billion to 164 billion due to outages and another 15 billion to 24 billion due to PQ phenomena So
57. ering 10 kHz 6GHz with powers up to 2 5kW is based on proven technology and the amplifiers are robust enough to meet the arduous conditions of EMC test applica tions Hundreds are in daily use in EMC labs and test houses all over the world The company also manufactures a range of unique quadrature hybrids couplers directional bridges and low power amplifier modules to supply the requirements of system designers New sales channels have been established on every continent and local representatives can be found on the new Vectawave website www vectawave com contactus Tel 44 0 1983 821818 sales vectawave com www vectawave com New 1200 page catalogue Pentair Equipment Protection the global business unit encompassing the Schroff Hoffman and McLean brands has brought out a comprehensive new catalogue detailing the entire range of Schroff products Over its 1200 pages the catalogue presents key technical information on cabinets cabinet accessories cases subracks power supplies cooling units and systems and backplanes for a variety of bus technologies Several new products are featured including a military approved version of the Varistar cabinet the minipac small case a europacPRO subrack for industrial and harsh environments and power supplies for MicroTCA and CompactPCI Serial systems For the first time the catalogue also covers selected products from the Hoffman and McLean ranges such as o
58. ewsletters by Dan Hoolihan Associate Editor IEEE Electromagnetic compatibility magazine Volume I Quarter 3 2012 page 22 http ieeexplore ieee org stamp stamp jsp arnumber 06347047 49 Oops that was a 1 550 Amp Lightning test not 150 Amp Pat Andr of Andr Consulting Inc shared a story that reminds us that it is good practice to ask more questions even if the answers seem obvious to get the needed solution As usual the story is told from Mr Andr s perspective While consulting for a client I was approached by a different company who was performing lightning testing at the same laboratory as my client s This company was having a great deal of difficulty passing a lightning test When I saw the unit and the test they were trying to pass my first question was Can you shield these cables I was told no The unit was small and although the test levels were not very high the size of the transient suppression required to pass this test would not have fit inside the box So We tried several other filtering techniques with very little success Therefore in desperation I questioned the client more about the shielding issue with the thought of approaching their customer and requesting if we could shield the signal cables in question They told me it was not the customer who said they could not shield the cables but another consultant who was worried about ground loops What Once
59. fessional staticdetails php course 216 Instrument PLASTICS LIMITED SPECIALISTS IN THE MANUFACTURE OF QUALITY ASSURED COST EFFECTIVE FILTERS EMC RFI Shielded Display Filter Windows Panels OPTOLITE CLEAR HSR OPTOLITE EMC SHIELDED WINDOWS OPTOLITE GLASS amp PLASTIC LAMINATED WINDOWS OPTOLITE COLOUR OPTOLITE INFRA RED FILTERS OPTOLITE BACKLIGHTS CIRCULAR POLARISING FILTERS LINEAR POLARISING FILTERS LIGHT CONTROL FILM ENHANCEMENT FILTERS DIFFUSERS Custom made to your requirements Instrument Plastics Ltd 33 37 Kings Grove Industrial Estate DOM be th ISO 0 REGISTERED FIRM Maidenhead Berkshire SL6 4DP UK wn E Tel 44 0 1628 770018 TAL Fax 44 0 1628 773299 Email sales instrumentplastics co uk Web www instrumentplastics co uk Banana Skins Editor s note I receive many potential Banana Skins and no doubt they are just the topmost tip of the EMI iceberg Keep them coming but please don t be disappointed if your contribution doesn t appear for a while or at all A special New Year edition of Banana Skins this time 8 pages Gai EM environment limitations in the safety information for a new smartphone Do not use your device near other electronic devices Most electronic devices use radio frequency signals Your device may interfere with other with other electronic devices Do not use your device near a pace maker e Avoid using your
60. fthe DM and CM noise currents will still flow over large areas but we design to ensure their loops we create with fuselage bulkhead levels are too low to cause filtering and RF deck hull fixed significant interference bonding installation s structural metal mesh whatever Figure 7 12 1 The intended situation mains filtering and RF bonding provide low Z local paths for noise generated by the power converter Figure 7 12 1 1s a copy of just the mains side of Figure 7 3 8 from 72 with a little more detail added to the AC mains supply to indicate a power distribution network It tries to show how by using a comprehensive mains filter single stage filter shown most practical filters will have two stages or more see Figure 7 3 9 in 72 we design so as to create small area local low impedance paths for DM and CM noise currents across their whole frequency ranges Then by Faraday s Law of Magnetic Induction one of Maxwell s four famous equations the noise currents will prefer to flow in the local loops we have created rather than flow in the mains distribution network where they can cause conducted and radiated emissions problems For more on this important EMC design technique which works with the laws of nature rather than against them and so achieves the greatest cost effectiveness see 32 33 85 and 111 Figure 7 12 1 also shows how we like to use CM chokes in our mains filters
61. gure 7 12 3 only shows a single phase system It also ensures that the power converter s external power supply has a high CM impedance from DC up to some low ish frequency perhaps several hundreds of kHz even one or two MHz for a low kW rated transformer decreasing in frequency as the power rating increases helping its mains filter to achieve its designed noise suppression whatever the impedance characteristics of the power distribution network over this frequency range The AC mains power distribution network single phase shown for simplicity At low frequencies an isolating mains transformer adds a very large series CM impedance Transformer design techniques e g interwinding screen s RF bonded to the RF Reference can increase this _ impedance and or increase its effective frequency range Figure 7 12 3 Using a mains isolating transformer Because the main problem is that RF suppressing CM chokes are predominantly inductive at low frequencies and so can series resonate with the CM capacitances naturally present in the power distribution network and or other equipment connected to it there are three alternatives to fitting a large and costly transformer as discussed above a Dampen the converter s mains filter b Increase the inductance of the power converter s input c Add line ground capacitance to the network Selecting mains filters so that they do not resonate when supplied or loaded w
62. h ground structures and compromise the correct operation of the insulation failure detection systems on the floating mains power distributions So for safety reasons the floating converter metalwork that the mains filters are RF bonded to must be made touchproof to prevent personnel from suffering electric shocks This can add extra design complexity and cost but it is certainly a much preferable solution than trying to use power converters and other electronic equipment without any mains filters at all Figure 7 13 4 provides a simpler view of the arrangement of the filtered floating power converter sketched in Figure 7 13 3 Everything within the dotted box is galvanically isolated from all earthed grounded structures and could be hazardous live due to leakage currents from filters and the power switching devices Figure 7 13 4 A simpler view of the floating power converter technique When using floating power distributions and floating power converters higher frequency noise emissions can be a little more difficult to control than when everything is directly bonded to the earthed grounded metal support structures These high frequency noise emissions can often be usefully reduced by connecting one or more low value capacitors from the floating RF Reference that has been created see Figure 7 13 3 to the local metal support structure which is usually earthed grounded as shown in Figure 7 13 5 The EMC Journal
63. h the results and of course it is allowing us to grow and develop the business REMC s European Sales Manager Paul Duxbury added We were really pleased that ETS chose to work with us on this project this new chamber represents a significant investment and development of their capabilities It is one which will bring them and their customers benefit for many years www etsemc co uk www rainfordemc com TUV SUD Product Service appointed by CESG to support National Security Certification Scheme TUV SUD Product Service has been appointed by CESG the UK s National Technical Authority for Information Assurance as a TEMPEST Test Facility under the CESG Formal TEMPEST Certification Scheme CFTCS TUV SUD Product Service has been evaluated according to the criteria of the CFTCS and has met the standard to be accredited to evaluate and certify products on behalf of CESG The CFTCS ensures that compromising emanations from Information amp Communications Technology ICT equipment are within the limits defined in NATO standards As well as submitting products for testing by TUV SUD manufacturers will have to undergo regular TEMPEST production Front Cover Hero image Electromagnetic Testing Services Rainford EMC Systems page 5 Circle top Vectawave Technology page 20 Circle middle Link Microtek page 20 Circle bottom EMC Partner page 20 Secretariat for EMCIA emcia Electromagnetic Compatibility Industry
64. he result can be real life interference problems and these issues were all previously discussed in sections 7 3 3 7 3 7 7 3 12 and 7 3 13 of 84 Complex i e frequency dependa nt distributed CM impedances shown lumped for simplicity ina equivalent CM circuit ar a Converter noisy Series and shunt CM impedances associated with the mains power distribution network and other equipment connected to it Series and shunt CM impedances associated with converter s mains filter and local RF bonding At some frequencies power distribution impedances might interact with the converter s input impedances allowing more CM noise to circulate in the external distribution network CM noise currents shown here Exactly the same happens with DM noise currents not shown possibly causing significant interference Figure 7 12 2 CM impedances in the power distribution can degrade mains filter CM attenuation at some frequencies Figure 7 12 2 reduces the above discussion to a set of lumped complex impedances trying to show that at certain frequencies the effects of the mains distribution and other equipment connected to it can cause mains filters to be less effective at certain lower frequencies Fitting an LF isolating transformer as shown in Figure 7 12 3 restores balance to three phase DM impedances which helps to keep mains harmonic emissions low and DM filters operating optimally but note that Fi
65. he trial was held in southwest England using the frequency of BBC Radio Devon and was codenamed project Mayflower Volunteer listeners reported favorably on the quality of daytime broadcasts but attempts at broadcasting after sunset were another story Nighttime changes in the atmosphere allow for distant off shore signals to interfere with DRM which in turn ceases to decode the signal causing an interruption in reception BBC spokesman said that the problem would require re planning the transmission network and or the building of new transmitters Industry analysts have concluded that the switchover from analog radio broadcasts is still some time away The entire 11 page report on Project Mayflower has been posted online http downloads bbc co uk devon pdfs project mayflower summary report pdf From the official report Given the additional interference to medium wave services from distant interferers which is apparent at nighttime the nighttime coverage was always expected to be smaller than the daytime coverage Indeed the DRM coverage at night is larger than the equivalent clean AM coverage at night It is important to note that the frequency we were using for DRM at Plymouth is particularly susceptible to interference from distant transmissions although it is not atypical of the situation that occurs on many AM frequencies assigned to BBC Local and network radio in the UK In some areas the frequency
66. ied in CISPR 16 so it called VHF Very High Frequency LISN It may actually be required to work above 300 MHz the upper limit of the VHF band This has resulted in a request to CISPR A to work on the specification validation and application of the new device The intention appears to be to apply it mainly to power cables EN TS 50217 This guide to in situ measurements of emissions is proposed for withdrawal as it is covered by CISPR 16 2 3 EN 55016 2 3 17 IEC EN 62488 This is a four part standard for PLC for power system applications Part 1 contains text on EMC matters that has not been reviewed by CENELEC and this will be addressed In IEC the ACEC committee is responsible for EMC reviews but there does not seem to be a running record of which documents have been reviewed The 62488 document was not reviewed in the period May November 2012 IEC TC77 Secretary Anew Secretary has been appointed This may have interesting consequences as the previous incumbent was very pro active and was not averse to controversy IEC 61000 6 7 EMC and functional safety A draft was circulated which evoked 39 pages of comments from national committees I first wrote 39 ages which may be prophetic Comments include critiques of the basic approach that specific limits can be set which ensure functional safety A recent meeting of the committee made significant progress partly due to an unusual attendance pattern
67. ig 2 Let s take EIA X7R for example at K tolerance The TCC Temperature Coefficient of Capacitance is 15 over the specified temperature range the tolerance is 10 so running at the extremities of the specification we may face a variation from nominal capacitance of 23 5 This will most likely be negative so if we assumed a nominal value of 100nF we now only have 76 5nF But what about when we apply voltage The VCC is not defined look closely at Figure 1 and the EIA definition of X7R and so there is no onus on the manufacturer to put this in the datasheet We will assume that our part is The EMC Journal January 2013 Possible VCC j Pd j u lis oO a lis 5 p E E o v F E i v Figure 2 Capacitance change versus voltage stress across dielectric 100V rated and we are going to use it at 80V Using a relatively conservative design this will produce a voltage stress between the electrodes within the body of the component of 3 2V um which will result in a drop in capacitance of around 40 see Figure 2 factor in the effect of temperature and the 10 tolerance and we could end up with only 40nF when we specified 100nF in the first place Bad as it sounds this is by no means the worst it gets With the pressures of price and size reduction manufactures of MLCCs are forever reducing dielectric thickness for end users voltage de rating is becoming a
68. in any modern home office or train Ga Action taken against Alternative Energy Medicine devices After reports in the national media spearheaded by the Seattle Times about the widespread fraud and health perils inflicted on American patients by the makers of electrical devices touted as miracle cures for serious diseases such as cancer and AIDS the Food and Drug Administration FDA has banned importation of the EPFX This desktop device is manufactured in Hungary by William Nelson a federal fugitive who fled the country in 1996 when faced with felony fraud charges Another electrical device under investigation is the PAP IMI Pap lon Magnetic Inductor a 260 pound electric pulsing machine that s been linked to patient injuries and deaths The latter is the invention of Prof Panos Pappas a Greek inventor and non physician Both these devices are based on the belief that the human body consists of energy fields and that altering those fields can improve or restore health Apart from the obvious dangers of subjecting the ill and injured to electrical charges physicians note the perils of delaying or rejecting medical care that might have helped Now the U S House of Representatives Committee on Energy and Commerce s Subcommittee on Oversight and Investigations has instructed the FDA to provide all relevant records on these devices their makers and distributors Of particular concern is the loophole posed
69. ing their operational lives in such a situation Editor Only 17 3 of LED lighting products sold in the EU complied with EMC Directive in 2011 Eighteen national market surveillance authorities MSAs involved in EMC ADCO participated in the campaign which was conducted between the Ist of January and the 30th of June 2011 A hundred and sixty eight 168 products were obtained and evaluated Ninety one 91 LED lighting equipment products were of Chinese origin whereas the origin of sixty five 65 products could not be determined Technical compliance with harmonised standards The notion of compliance is to be understood as compliance with an applicable harmonised standard The results of the technical compliance with the applicable harmonised standards showed large differences e Rather low compliance with the emissions limits 61 5 of the tested one hundred and sixty six 166 products were found to be compliant e There was a better level of compliance with the immunity limits 91 5 of the tested forty six 46 products were found to be compliant Within this market surveillance campaign an additional study on harmonic current emissions EN61000 3 2 was carried out When applying the same harmonic limits as those for compact fluorescent lamps one out of two samples 46 of the assessed LED lighting equipment failed This is clear evidence for the need of a prompt amendment of EN61000 3 2 Administrat
70. itation system s control panel and his 5 watt walkie talkie transceiver was clipped to the belt at the center of his back When he pressed the Push to Talk button on his microphone his back and the radio s antenna was much less than 1 metric meter from a static transformer differential relay for the unit s step up transformer The relay had been designed to meet the then current RF immunity level in IEEE Std C37 90 2 10 volts meter The EMC Journal January 2013 That standard also included in boldtype a Caution statement alerting users to maintain a separation distance of at least one metric meter between a transceiver s antenna and any sensitive equipment However with less than half that separation distance the RF field strength at the relay was much higher than 10 V m The relay incorrectly operated and the turbine generator tripped off line The next revision of IEEE standard C37 90 2 1995 raised the required immunity level to 35 V m which is the RF field strength from a 5 watt transmitter s antenna at a distance of 50 centimeters 6 inches where it remains today In spite of repeated attempts by electric utility engineers who are members of their county s IEC TC 95 delegation the immunity level specified in IEC standard 60255 26 for measuring relays and relay systems remains at 10 V m In the late 1970 s a vacuum tube based automatic synchronizing relay failed catast
71. ith complex impedances in real life as distinct from the resistive 5002 impedances that are used in all EMC test laboratories for mains sources and loads was covered in Sections 7 3 7 and 7 3 8 of 84 so I won t repeat that material here When we are constructing our own mains filters we need the damping information given in Chapters 5 2 8 and 5 2 9 of 3 Items b and c in the above list both have the same aim and may be applied individually or together to reduce the resonance frequency of the distribution network so that it is much lower than the lowest noise frequency fyw emitted by the power converter which is its lowest switching chopping frequency There are two main concerns with manipulating the resonances caused by the interactions between the impedances in the power distribution network and those in the converter s mains input 1 This type of approach is unsuitable where the configuration of the power network could change unless so much line ground capacitance or series inductance is added that in all possible configurations the series resonant frequencies are much lower than fyw ii We should not try to be too clever by carefully tuning the series resonances to lie between two of the line spectra in the converter s noise emissions Natural variability in the capacitance of the power distribution network and its connected equipment could cause this frequency to change over time and Murphy s Law tells us that
72. ittest EMC in Electric Power Substations by John T Tengdin P E OPUS Consulting Group j t tengdin ieee org Co Chair IEEE Power and Energy Society PES Working Group C2 Substations published in the IEEE Electromagnetic Compatibility Magazine Volume l Quarter 2 http ieeexplore ieee org stamp stamp jsp tp amp arnumber 6244983 Ga Pocket Wi Fi hotspots paralyse Chinese metro lines Shenzhen Metro is blaming customer W1 Fi for disruptions to its service The subway system for the city of Shenzhen in Guangdong province China depends on the unlicensed 2 4GHz band to link up its signalling systems Following network failures in October and a trial blocking of 3G signals earlier this month the Shenzhen tube operating company wrote to China s regulator asking for permission to block the signal Caijing magazine 1 reports that permission has now been refused leaving Metro bosses at a loss on how to resolve the issue which has seen two lines of the network repeatedly shut down and threatens other systems around China Customer Mi Fi devices create Wi Fi hotspots that are backhauled over China Mobile s 3G network and they re very popular particularly in Shenzhen which the South China Morning Post tells us accounts for 80 per cent of sales 2 That s the legit kit which only nudges the 100mW legal cap but engineers trying to keep the network running reckon black market devices are ki
73. ive compliance The overall administrative compliance was only 28 8 and mainly regarded the CE marking and the Declaration of Conformity DoC requirements Almost 9 of the assessed LED lighting equipment did not carry the CE marking whereas almost 24 were either not CE marked or did not carry a correct CE marking format and size as required Declarations of Conformity were available for 125 74 4 of the assessed LED lighting equipment with almost half of them having major deficiencies e g missing reference to the Directive incorrect Directive identification of the product incorrect standards not issued by the manufacturer and or authorised representative etc Overall for 67 39 9 of these products an acceptable Declaration of Conformity was presented General In general the level of compliance of the LED lighting equipment with the technical and administrative requirements was considered insufficient Overall only 29 17 3 of the products were in line with both technical and administrative requirements The assessment of the technical documentation and of the immunity requirements were performed on an optional basis the results of this assessment have not been taken in account in the overall level of compliance This means that the overall level of compliance could be lower 1f both requirements had been assessed Taken from Final Report on the 4 Joint Cross Border EMC market Surveillance Campaign
74. l RF Reference etc to increase the frequency range over which they provide high CM impedance Remember they only need to provide high CM impedance up to the frequency at which the RF CM chokes start to behave predominantly resistively see Section 5 2 6 in 5 When using an isolating mains transformer it may be possible to reduce the cost of the power converter s mains filter s CM The EMC Journal January 2013 filtering circuits possibly even eliminating them entirely A mains isolating transformer might also prove to be sufficient on its own without any mains filter at all to prevent the CM noise from a power converter s mains input from circulating widely in the power distribution and exceeding limits or causing interference Of course without an associated DM mains filter an isolating transformer would do little possibly nothing for the power converter s DM noise emissions or the resulting mains waveform distortion but this is often not as much of a problem as the CM noise emissions anyway Where a power converter is fitted with a mains filter that deals with CM noise as well as DM the majority of problems with widely circulating CM currents occur at lower frequencies below 150kHz In this case experience seems to show that the normal type of construction for an isolating transformer is adequate for controlling CM currents in this frequency range A recent example of using a mains isolating transformer
75. le from the archives at www theemcjournal com 13 The EMC design of SMP switch mode power and PWM pulse width modulated power converters Keith Armstrong The EMC Journal Issue 93 March 2011 pages 26 34 available from www theemcjournal com 14 Keith Armstrong s earlier articles are available from the archives at www theemcjournal com 15 Textbooks by Keith Armstrong and others are available from www emcacademy org books asp 32 Key knowledge for the efficient design of electronic products and their EMC that we were never taught at university Keith Armstrong ANSYS Next Generation Signal Integrity and EMI Simulation Seminar 23rd March De Vere Milton Hill House Oxford download via http www ansys com en_uk Downloads SIUK or direct from Wwww ansys com staticassets ANSYS 20UK staticassets Keith_Armstrong _Presentation_ANSYS_March_23 202011 pdf 33 Maxwell s equation Quantum Electrodynamics and good installation practices for SI PI and EMC Keith Armstrong The EMC Journal Issue 91 November 2010 pages 32 46 54 A brief look at offshore power quality Ian C Evans EMC UK 2011 conference session on EMC in Buildings and Infrastructure October 11 2011 http www emcuk co uk conference 60 Guidance Notes on Control of Harmonics in Electrical Power The EMC Journal January 2013 Systems American Bureau of Shipping Publication Number 150 May 2006 from www eagle org eagleE
76. lone articles each covering a single topic the issue of suppression is so large that it is impossible to publish it all in a single issue However I have mostly succeeded in compartmentalising individual suppression topics in each article 7 12 EMC benefits of AC mains LF isolating transformers Where a power converter shares an AC mains power distribution network with other electronic equipment which are probably fitted with mains filters a number of EMC issues arise that might be best dealt with by fitting the converter with a dedicated LF mains isolating transformer In earlier articles in this series I called mains transformers Low Frequency LF transformers to distinguish them from the High Frequency HF transformers that can be used to provide galvanic isolation at the switched or chopped outputs of power converters Nominal mains power frequencies range from 16 2 3Hz through the more familiar 50Hz and 60Hz to the 400Hz generated by the electrical generators fitted to aircraft engines One of the main reasons for using switched mode power conversion technologies is to achieve galvanic isolation for safety reasons with lower cost and weight by replacing the large heavy costly LF isolating transformers used in traditional linear power converters with much smaller HF transformers The EMC issues associated with HF isolating transformers were discussed in section 6 of this series in 66 However
77. manufacturer LEONI AG Prior to that he developed his extensive technical knowledge and understanding of the automotive electronics market working as an electrical engineer for EMI em CI A Member An Open Invitation To Our Readers Hursley EMC Services have relocated a few hundred yards to a new 10 000 sq foot purpose built laboratory in Chandlers Ford Hampshire They are planning an Open Day event in March date to be confirmed for all interested parties to view their new improved facilities Readers of the EMC Journal are therefore invited to contact Hursley EMC if they wish to attend For further information and to register your attendance please contact Anna Pettit on 02380 271111 or e mail anna hursley emc co uk News and Information University of Oxford High speed Digital Engineering and EMC Led by Dr Howard Johnson author of High Speed Digital Design A Handbook of Black Magic this programme offers a number of short courses delivered by some of the world s leading digital design experts Celebrating 20 years of High Speed Digital Engineering at Oxford Dr Howard Johnson will return to Oxford for the 20th and final time in June 2013 to teach his courses High Speed Digital Design Advanced High Speed Propagation e High Speed Noise and Grounding Signal This will be the last time Dr Howard Johnson s courses are available in Europe For digital logic engineers system architects
78. may have to be a compromise between the value needed to control the lowest noise frequency to be controlled fn and the value above which the leakage current is considered excessive by the relevant safety standards or which compromises the operation of the insulation failure detection circuits on the floating power distribution This is pretty much the same set of design compromises as when adding noise suppression capacitors as sketched in Figure 7 13 5 It is of course very important indeed to always ensure that all relevant safety standards are fully complied with and that the product system or installation will be safe over its anticipated lifecycle There is a way to completely eliminate the safety and construction problems of having to float power converters and their filters when using floating mains supplies as well as avoiding the compromises and non idealities of capacitive cable shield RF bonding fit the converter with an isolating LF mains transformer as discussed in Section 7 12 above With a co located LF isolating transformer in series with the power converter s mains input the converter s chassis frame enclosure etc and all of its associated filters and cable shields armour can be directly RF bonded to the local earth ground metal structure and use it as an RF Reference without compromising the floating mains distribution in any way except for the small CM leakage current from primary winding to secondary and
79. me extracts from the Introduction to Economic Framework For Power Quality CIGRE CIRED Joint Working Group C4 107 June 2011 ISBN 978 2 85873 157 2 available from http www scribd com doc 71715649 467 Economic Framework for Power Quality Also see THE ECONOMICS OF POWER QUALITY A SYSTEMATIC FRAMEWORK FOR THE ASSESSMENT by Jos Luis Guti rrez Iglesias The Members of JWG C4 1071 and Alex McEachern CIR ED 19th International Conference on Electricity Distribution Vienna 21 24 May 2007 Paper 910 http www cired be CIREDO7 pajs7CIREDZO07 _0910_paper pdf Earth s magnetic field reversal possible knocking out satellites Could we be witnessing the start of a reversal of Earth s geomagnetic field That s the tentative suggestion from computer models created by Peter Olson and Renaud Deguen of John Hopkins University in Baltimore Maryland Nature Geoscience DOI 10 1038 ngeol506 A reversal could expose us to solar winds capable of knocking out power grids Taken from Magnetic reversal in the 60 Seconds column of New Scientist 7 July 2012 page 7 www new scientist com The geological record shows that the earth s magnetic field has reversed many times in the past so it is expected to reverse again in the future When it changes it seems to change quite quickly with a period of low or zero field inbetween Many satellites would also be exposed to increased radiation shorten
80. metal enclosure use that enclosure or an internal chassis or frame as their RF Reference and have no need for an external RF Reference If you remembered Figure 7 2 4 without me having to tell you you might also remember that the figure that preceded it was of course Figure 7 2 3 which I have duplicated in this article as Figure 7 13 3 9 a ipi a ee ee Figure 7 13 3 Example VSD fitted with filters and RF bonded together Notice that Figure 7 13 3 shows no connections to earth or The EMC Journal January 2013 ground because earth or ground electrodes rods stuck in soil etc have no relevance at all for the noise emissions generated by any electronic devices such as the power converters that are the subject of this series So there are no EMC problems at all in using mains filters on power converters that are powered by floating mains power distribution networks However there can be some practical issues that need to be taken into account Because the filters fitted to the inputs and or outputs of power converters must be RF bonded to the converters metalwork usually their chassis frames or enclosures using them as RF References to provide small low Z current paths when using floating mains supplies this metalwork must not connect directly to the earthed grounded structure of the vessels or sites This is so that the filters leakage currents will not flow into the eart
81. n done during the rig s original design and construction by properly suppressing the power inputs and motor outputs of all of the crane motor drives He said that much of the rig is still suffering the full force of the CM voltage noise caused by the absence of mains filters on any of its variable speed motor drives including the 700kW drives for the cranes Figures 7 12 5 through 7 12 7 are only associated with one of the crane motor drives the other motor drives associated with cranes pumps and other functions all still creating similar types of CM noise on the power distribution but had not been seen to cause the safety problems with crane control that meant the rig could not be operated The manufacturer of the rig had made many similar offshore drilling rigs beforehand and never fitted any of their variable speed motor drives with mains filters because they said they were not needed and so they saved their cost Well like most such bad EMC engineering cost cutting decisions it only took one EMC problem to cost very much more than all the money that had ever been saved by deviating from good EMC design principles for the sake of reducing costs Quite possibly the reason why they had crane control problems on this rig when they hadn t seen any similar problems on previous rigs was because of a change in the design of the electronic control equipment and or silicon die shrinks for most all of the integrated circui
82. n and the power networks would fail too often When controlling a vessel like a ship an interruption in the power that impairs the control can cause huge safety risks e g running onto rocks So they use floating mains power networks fitted with sensors to measure the normally high impedance between each phase or neutral and the earth ground of the vessel or site to determine when insulation failures have occurred and be able to fix them before another one happens Mains filters have leakage currents in their earth ground labelled terminals which would prevent the insulation failure detectors from working correctly The common mistake goes on to say that in such situations the only mitigation possible is to ensure that all the other equipment on the site is immune enough to the noise suffered by the power distribution system which 1s easier said than done if they can t use mains filters This mistaken approach ignores the possibility of interference with other equipment on other vessels or off site and with radio receivers used anywhere so is far from being any kind of real EMC solution Anyway as the offshore drilling rig example above showed see Figures 7 12 5 6 and 7 it can be very difficult to predict whether unfiltered power converter noise emissions will cause interference problems with the rest of the system until everything is installed and operating By which time of course any fixes will be time consuming an
83. nce that the installation and calibration of a new 3m Semi Anechoic chamber at their facility near Stebbing Essex has recently been completed The new chamber which is housed in a newly built extension greatly enhances the facilities at ETS and means that full compliance radiated emission 30MHz 18GHz and radiated immunity 80MHz 6GHz measurements can now be performed without the need of the Open Area Test Site The chamber has a large 2m wide by 2 1m tall access door 2m diameter turntable and floor loading of 1000kg m This means that larger EUT s which previously could only be tested on the OATS can now be handled with relative ease and in the comfort of an indoor environment The installation of the new chamber which was designed manufactured and installed by Rainford EMC Systems began in mid October and following calibration was completed in late November Since early December the chamber has been in constant use by customers George Vasilla Managing Director of ETS commented that We chose to work with Rainford EMC Systems on this new chamber due to their experience and track record of providing chambers Throughout the entire project from concept to completion we had a really good relationship with them and were able to continue our normal day to day operations with only minimal disruption All the staff at ETS and the customers who have so far used the new chamber are very impressed wit
84. o uk 8 amp 9 October 2013 The Racecourse Newbury Make a Note in Your Diary Now www emcuk co uk Make the Connection Find the simple way through complex EM systems with CST STUDIO SUITE Components dont exist in electro If you re more interested in microwave gi magnetic isolation They influence components or signal integrity analysis their neighbors performance They are affected by the enclosure or structure around them They are susceptible to outside influences S i we ve a wide range of worked applica e lt tion examples live on our website at With System Assembly and Modeling CST STUDIO SUITE helps optimize component and system performance Involved in emc emi analysis You can read about how CST techno logy is used for EMC EMI analysis at Get the big picture of what s really going on Ensure your product and components perform in the toughest of environments Choose CST STUDIO SUITE Complete Technology for 3D EM A Revolutionary Solution For Laser Powered Field Measurements Beas es h a J Lis a Modulated And CW Electric Field Measurements Are Faster Fasier And More Accurate AR s new series of laser powered electric field analysers have an extremely high sample rate and can precisely measure pulsed electric fields in the microsecond range That doesn t just mean they re fast it means they re much more accurate than any other kind of field monitor equipmen
85. on testing to demonstrate conformity with verifiable and repeatable standards specified by CESG and is underpinned by an effective quality management system The new scheme seeks to achieve assurance based on compliance at every stage of a product s life from its initial design onwards It supports the Government s UK Cyber Strategy ensuring that TEMPEST services comply with the updated NATO SDIP 55 standard and is compatible with the EU s TASG4 04 standard www tuv sud co uk Production amp Circulation Director Pam A Hutley pam nutwooduk co uk nutwood UK LIMITED Nutwood UK Ltd Eddystone Court De Lank Lane St Breward Bodmin Cornwall PL30 4NQ Tel 44 0 1208 851530 Fax 44 0 1208 851630 Web www theemcjournal com Nutwood UK Limited January 2013 The EMC Journal January 2013 News and Information AR Europe announces new distribution agreement with Eastern Optx AR Europe is proud to announce their new exclusive distribution agreement with Eastern Optx a New Jersey based company that designs and manufactures fibre optical delay systems This new product line includes radar target simulation systems radio altimeter test sets and channel replicators The Eastern OptX products are available for the European market through the AR Europe sales channels from December Ist 2012 At present this agreement applies to the entire AR Europe channel excluding the German and Italian markets With i
86. on the power rails from exceeding the ICs DC operating thresholds This may require a minimum value of total capacitance in the system Since it s usual for a decoupling regime to have many capacitors in parallel it becomes a straightforward matter to calculate e g using Figure 2 or similar data by how much to increase the overall required capacitance given a particular DC rail voltage and capacitor rating to allow for the VCC The EMC Journal January 2013 Filtering The situation with filter capacitors is somewhat different Here lower frequency applications are more typical For both supply conducted emissions and conducted immunity the bottom frequency is 150kHz for commercial applications and considerably lower for military and aerospace In the kHz region supply filtering is largely a matter of getting the maximum capacitance in the smallest space for a given voltage with secondary issues such as leakage current and surge protection also being important In signal line filtering an additional aspect is that the capacitor should not affect the desired signal bandwidth so there can be a critical trade off between this limitation and the lowest effective filtering frequency In either case there is real pressure on the MLCC characteristics and it will be important to evaluate the effect of VCC on the filter s performance A necessary consequence is that pre compliance design EMC testing should be done with worst case DC
87. onnections that achieve low enough impedances at the lowest frequency to be controlled i e at f n and also at the highest frequency to be controlled i e at f aS sketched in Figure 7 13 6 Metal chassis hull deck bulkhead fuselage etc for which we use the IEC symbol that ooks something like this Capacitor RF bonds spaced apart by no more than A 10 at Jmax all around the perimeter of the electronic unit Low capacitors with very short connections between the unit s RF Reference and the metal chassis hull fuselage etc Figure 7 13 6 Capacitive RF bonding for isolated electronics powered from a non isolated DC power network These capacitors should be spaced no further apart than 4 10 at the highest frequency to be controlled fax Another way of stating this is lt 30 f in air with fay in MHz giving the maximum spacing in metres whereas in GHz gives the spacing in millimetres max References for this article only 5 EMC Design Techniques for Electronic Engineers Keith Armstrong Armstrong Nutwood UK Nov 2010 ISBN 978 0 9555118 4 4 from www emcacademy org books asp 11 When the going gets tough smarter design wins Keith Armstrong The EMC Journal Issue 81 March 2009 pages 21 24 available from the archives at wwww theemcjournal com 12 BOM cost and profitability Keith Armstrong The EMC Journal Issue 82 May 2009 pages 32 34 availab
88. orks and floating electronics One of a number of Stand Alone articles on the EMC design of switch mode and PWM power converters of all types By Keith Armstrong Cherry Clough Consultants Ltd www cherryclough com Issues 93 101 of The EMC Journal carried the preceding parts of this Stand Alone series my attempt to cover the entire field including DC DC and AC DC converters DC AC and AC AC inverters from milliwatts mW to tens of Megawatts MW covering all power converter applications including consumer household commercial computer telecommunication radiocommunication aerospace automotive marine medical military industrial power generation and distribution in products systems or installations Hybrid amp electric automobiles electric propulsion traction green power e g LED lighting and power converters for solar PV wind deep ocean thermal tidal etc are also covered Issues 93 95 used a different Figure numbering scheme from the rest for which I apologise I generally won t repeat material I have already published instead providing appropriate references to the EMC Journal 14 and my recently published books based on those articles 15 so that you don t get bored by repetition 7 Suppressing RF emissions from inputs and outputs I began Section 7 in Issue 98 72 and so far it has continued up to Issue 103 108 Despite my aim to only publish stand a
89. ostly techniques which clearly should not be hampered The following standards are some of those in the course of maintenance IEC 61000 3 3 The revision to create Edition 3 attracted no negative votes at the CDV stage so automatically goes forward to publication with no FDIS voting stage IEC 61000 4 6 This revision has reached the CDV stage with significant doubt about some fundamental technical issues which is most undesirable National committees need to look more carefully at CDs now that time scales for the completion of products are being made ever shorter Although there were 23 pages of comments several of a technical nature the revision will proceed directly to publication with no FDIS vote because 29 countries out of 32 voted for it including some that submitted numerous comments This is surely a situation that creates considerable concern IEC 61000 4 30 This is at the CD stage and illustrates the point I make above three important national committees have simply expressed support but there are 34 pages of comments from ten other national committees It does not seem likely that a large proportion of these comments are without foundation A second The EMC Journal January 2013 CD has been produced IEC TS 61000 6 5 This is a Generic TS on immunity in power station and substation environments and it has been decided to convert it to a standard Planned changes include the deletion of switchgear
90. p with only 1 25nF We can t just add more capacitors in parallel because it will push us over the 45uC limit we could matrix parts in series and parallel to reduce the voltage stress and keep the nominal capacitance low but this will take up a lot of space and be costly A more stable capacitor is required Stored charge 100 45uC Voltage kV oS 0 1 Capacitance nF 1 10 100 Figure 3 Stored charge of 45uC for voltage and capacitance Luckily some X7R materials are more stable than others and if requested more suitable capacitors can be manufactured Syfer can manufacture a 3640 InF 10kV which will have less than 50 capacitance drop at 8kV using this in the previous example would provide a residual capacitance at operational voltage of around 2 6nF as opposed to 1 25nF which would allow the circuit to function correctly and even allow for a reduction in component count from 5 to 4 The EMC Journal January 2013 The effect on EMC design What does this effect mean for EMC related design issues There are two principal widespread uses for MLCCs that are relevant to EMC interface filtering and decoupling Whether a change in capacitance has a serious effect on either of these applications depends more than anything on frequency This is because EMC applications cover a broad bandwidth and the capacitor may be being used either above or below its self resonant frequency Stable X7R dielectric Impedance
91. pen frame racks for datacom applications outdoor cabinets for wall pole or ground mounting and both indoor and outdoor air conditioners for industrial systems In addition users will find comprehensive gt PENTAIR service options and project examples for each product in the ServicePLUS pages This easy to use catalogue is clearly laid out in colour coded sections and makes generous use of colour pictures line diagrams and tables It can be obtained by visiting www schroff co uk and clicking on the Catalogue Request button Tel 44 0 1442 218726 keith reynolds pentair com www schroff co uk AR introduces new family of 400 MHz Solid State RF Amplifiers AR REF Microwave Instrumentation has introduced a new family of solid state RF amplifiers that instantaneously covers the 10 kHz 400 MHz frequency range with both 200 watt and 400 watt models The amplifiers are designed to deliver all the power required for applications using MIL STD DO 160 and other automotive standards These models can be used independently or with AR s RF conducted immunity generators when specific tests require higher powers than our standard CI Systems can generate Model 200A400 and Model 400A400 the 200 and 400 watt models respectively each utilize the highly linear devices in all high power stages to reduce distortion and improve stability Each model is equipped with a Digital Control Panel DCP which provides both
92. r device may interfere with the aircraft s electronic navigation instruments Your device may interfere with automotive equipment Electronic devices in your car may malfunction due to radio interference from your device Contact the manufacturer for more information Do not store your device near magnetic fields e Your device may malfunction or the battery may discharge from exposure to magnetic fields e Magnetic stripe cards including credit cards phone cards passbooks and boarding passes may be damaged by magnetic fields e Do not use carrying cases or accessories with magnetic closures or allow your device to come into contact with magnetic fields for extended periods of time Taken from the Safety Information section of the User Manual of the latest model of a popular and highly regarded smartphone purchased in September 2012 Notice that the smartphone user is required to be knowledgeable about EM environments and potentially explosive atmospheres and to be continually monitoring their EM environment for magnetic fields with no maximum level specified Also the requirement to not use the phone near other electronic devices gives no guidance on what is too near If the word near means the same as in the normal EMC emissions and immunity standards that are used to provide compliance with the EMC Directive this effectively means the user instructions do not permit the smartphone to be used
93. r testing electronics and receivers for radio frequency interference Interestingly his first real world application of his EMC background was at the start of his EMC career in the early 1950 s He had just graduated from the Illinois Institute of Technology and took a job at Chicago Aerial Survey in Chicago There was interference to anew aerial camera aboard a US Air Force bomber The camera caused interference to the bomber s autopilot programming Jim was called and after review of the situation had shielding installed by the manufacturer s camera This solved the problem and there were no further EMC issues with the autopilot system From that point on he became the RFI expert The EMC Journal January 2013 Taken from Completed Careers by Don Hierman Associate Editor IEEE Electromagnetic compatibility magazine Volume I Quarter 3 2012 page 58 http ieeexplore ieee org stamp stamp jsp arnumber 06347052 45 Beer Blacks Out TV In a reprint of a United Press International Dispatch dated May 31 1962 it was stated Rochdale England Television sets in the neighborhood of the Dog and Partridge pub are back to normal now that they discovered that the trouble was caused by beer Engineers found interference was caused every time the barkeeper drew a beer from one of the pub s seven spigots so they neutralized the spigot Taken from 50 25 10 Years Ago A Review of EMC Society N
94. r the Rosslyn Metrorail station that were the result of a loss of train detection The track circuit in that case failed to detect the presence of stopped trains between the Foggy Bottom and Rosslyn stations Tests on the circuit modules from the Rosslyn event conducted in 2009 as part of the Fort Totten investigation showed that the Rosslyn modules exhibited parasitic oscillation and archived data showed that the Rosslyn track circuit had experienced this problem from as far back as 1988 the earliest time from which data were available In response to the Rosslyn event WMATA developed and issued technical bulletins requiring the use of an enhanced circuit verification test procedure However none of the WMATA technicians interviewed as part of this investigation was familiar with the enhanced procedure Taken from Collision of Two Washington Metropolitan Area Transit Authority Metrorail Trains Near Fort Totten Station Washington D C June 22 2009 Railroad Accident Report NTSB RAR 10 02 National Transporta tion Safety Board Washington DC 2010 www ntsb gov doclib reports 2010 RAR1002 pdf The costs of poor power quality a CIGRE CIRED report Many professionals including industry regulators consultants system and installation designers maintenance managers production managers and financial managers are concerned about the impact of the costs of poor power quality on businesses and how these costs c
95. re and reliable protection to sensitive electrical and electronic control systems in industrial applications For more information visit www pentairequipmentprotection com Another solution provided by Eastern OptX is the radar altimeter test set This is also a fibre optical based system and is used in the calibration procedures for altimeters This products wideband capabilities offer some great advantages especially in cases where the new LPI Low Probability of Intercept Radio Altimeters are used in Military applications such as helicopters and UAVs These wideband spread spectrum like signals can easily be handled by Eastern OptX delay lines where IF based system suffer in frequency agility To test radio network connections Eastern OptX s channel replicator system offers a simulation capability for a multi radio network allowing reliability testing of the communications network for propagation effects and to test multi vendor interoperability For further information contact Mark Reeve on 44 0 1908 282766 mreeve arworld us EMCIAa Member In his new role Tiberius will be responsible for developing and managing the company s activities and business in key automotive customers with primary focus in Germany He will also provide support to coordinate automotive projects with Chomerics divisions on a global basis Before joining Chomerics Europe Tiberius worked for the German automotive cable and wiring harness
96. re occurring on Static terminals in relay control houses often many feet meters from the high voltage bus work The failures were in the transistors connected to the VT CT and DC control conductors in the control house Slowly energizing or de energizing just one of the capacitance elements e g capacitor banks coupling capacitor voltage devices circuit breaker bushing capacitance as shown in Figure 1 can create the oscillatory Surge Withstand Capability SWC transient Because of the slow moving switch the result is a sequence of flash overs energizing followed by decaying oscillations to zero then repeated until the switch is fully closed or open The rise time was in the micro second range to a peak of several kV the oscillations in the 1 Megahertz range decaying to 50 in a few cycles with repeats at many times per second This transient now is a part of IEEE standard C37 90 1 as the oscillatory SWC test From its beginning in 1974 the required peak voltage for this transient test has been 2 5 kV at all locations indoor and outdoor The comparable IEC standard IEC 60255 28 requires this level for outdoor installations but only 50 of that for indoor installations In the mid 1970s at Philadelphia Electric s Eddystone Generating Station a control technician was beginning the task of tuning the excitation system of one of the 380 000 kW supercritical steam turbine generators He was bent over the exc
97. rom the programme of work of IEC SC77A IEC 61000 3 10 This was intended to be a standard for emissions in the frequency range from the 40th harmonic to 9 kHz but no progress could be made over many years due to changing technologies and lack of data on which to base realistic requirements It is still in the programme of work but no group is at present assigned to work on it IEC 61000 3 11 This standard complements IEC 61000 3 3 for products drawing more than 16 A but less than 75 A per phase and for products drawing less than 16 A per phase which cannot meet IEC 61000 3 5 IEC 61000 3 12 This standard complements IEC 61000 3 2 for products drawing more than 16 A but less than 75 A per phase It takes a very different approach from that of IEC 61000 3 2 basing limits on the ratio of the load impedance to the supply impedance IEC TR 61000 3 13 This advisory Report is about emission limits for unbalanced loads connected to MV HV and EHV systems IEC TR 61000 3 14 This Report concerns the assessment of emission limits for harmonics interharmonics voltage fluctuations and unbalance for loads connected to LV systems IEC TR 61000 3 15 This Report is about emission and immunity limits for dispersed generation systems a complex matter It was originally intended as standard then as a TS and finally considering that the technology is not yet mature it remains a Report but perhaps not for ever At present ther
98. ropagation 20 21 June 2013 High Speed Noise and Grounding 24 25 June 2013 Printed Circuit Board Design for Real World EMI Control 25 26 June 2013 Advanced EMC Fullwave Modelling for EMC and Signal Integrity 27 28 June 2013 Introduction to Data Converters 2 day course June 2013 dates to be confirmed Advanced Data Converters 2 day course June 2013 dates to be confirmed Electronic Product Design and Retrofit for EMC 2 day course June 2013 dates to be confirmed High Frequency Measurements probes and equipment used in Signal Integrity and EMC work 2 day course June 2013 dates to be confirmed e EMC and ESD Lab Techniques for Designers troubleshooting to proactively avoid field or compliance problems 1 day course June 2013 date to be confirmed e Advanced Troubleshooting Techniques for Circuits and Systems 1 day course June 2013 date to be confirmed e Power Distribution Design 2 day course June 2013 dates to be confirmed e Suspect Counterfeit Detection Avoidance and Mitigation 2 day course dates to be confirmed This programme of short courses for professionals working in digital engineering and EMC related fields is held each year in June with some courses repeated in November December each year It is the only public training programme in Europe to feature courses by Dr Howard Johnson For more information go to http www conted ox ac uk courses pro
99. rophically More specifically a transient of unknown origin had caused a hole to be burned through the glass envelope of a vacuum tube in its operating circuitry The failed relay was mounted on the control panel for a barge mounted peaking gas turbine generator at the Consolidated Edison s Gowanus Generating Station There was no voltage on the barge higher than 15 kV and even so the relay design had been tested and met the oscillatory SWC test now in IEEE Std C37 90 1 William E Kotheimer was able to replicate the failure he burned a similar hole in the vacuum tube s glass envelope But this time with an even better storage oscilloscope he was able to capture the source of the transient It was the seemingly innocuous DC auxiliary relay on the same panel a GE HFA six pole hinged armature auxiliary relay designed for use in interlocking circuits There was no operating speed requirement as the most important design criterion was low battery drain In some applications the relay might remain energized for weeks or months The manufacturer s catalog listed the 125 V coil as 2000 ohms thus a low battery drain of 62 5 milliamps The catalog included no information as to the coil s inductance After all it was just a simple auxiliary relay 12 The transients were generated when a slowly opening external contact attempted to interrupt that 60 milliamp current through the HFA relay s 25 henry operating coil As
100. rrents from the crane s 700kW drive flowing in an uncontrolled manner all over the structure of the drilling rig which had not been constructed to act as an RF Reference at such frequencies resulting in the gross phase neutral earth ground noise shown by the red trace on Figure 7 12 5 plus many problems with stray coupled noises on sensor and control cables due to the large noise voltages arising between different parts of the rig s structure which caused the crane control gear to lose control in turn causing major safety hazards that prevented the use of the rig The switching frequency of the crane s 700kW motor drive was 2kHz as is the noise on the red trace of Figure 7 12 5 A spectrum analysis of the noise showed that it continued at significant levels up to about 2MHz which is typical for unsuppressed high power switch mode power converters 1000 times the switching rate Figures 7 12 6 and 7 12 7 are pictures of the transformer that was added to give the blue waveform in Figure 7 12 5 and its installation Figure 7 12 6 The new 1MW isolating transformer that cured the CM waveform distortion Figure 7 12 7 Another view of the new transformer now in its weatherproof cabinet The power quality expert complained that the drilling rig s manufacturer constrained him to use quick and dirty methods to remove the most obvious problems rather than solve the problems at source as he wanted to and should have bee
101. s transport RF and digital signals in the presence of intense electromagnetic fields The point2point range brings new functionality to the timing and monitoring applications in high energy physics Together with our RF sensors and probes these optical links meet the needs of EMC EMP lightning test and Tempest applications FEATURES DC 3GHz in 6 bands Flat frequency response Low noise Defstan 59 411 MIL STD 461 Wide dynamic range High stability Galvanic isolation DC single or multimode fibre compatible C Kemtron Pectromagnmetic Compatibility EMC Comoonenis and Gasket If information in the catalogue changes Kemtron publishes updates on their website http www kemtron co uk Please contact Kemtron to order your free copy of the catalogue Tel 44 0 1376 348115 info kemtron co uk www kemtron co uk emMCiA Member BENEFITS Electrical performance independent of distance Reliable measurements Safe HV measurements EM hardening Repeatable measurements available from PPM call 44 0 1 793 784389 or visit www point2point co uk 21 What capacitance do you get when you buy a multilayer ceramic capacitor This might sound like an odd question it is the value specified in the datasheet surely The actual answer is down to dielectric type design and operational conditions and there is a surprising degree of variation There are many factors which affect the actual capacitanc
102. se Mr Howard said his bore pump had blown up twice and an electric fence had been damaged during thunderstorms since the installation of the masts The report by EMC Technologies said the ground current associated with lightning strikes could affect equipment connected to the mains Mr Howard wants the towers moved to their originally planned positions or his house and sheds relocated Moyne Shire has estimated the cost of moving the buildings at 880 000 Mr Howard said the battle had already cost 500 000 stand to lose the farm over this Mr Howard said I have done nothing wrong and I m determined to see that the council is held responsible for the action of its officer who gave verbal consent when he had no right to do so Moyne Shire chief executive Brett Stonestreet declined to comment Taken from Interference Technology magazine s on line newsletter http 72 29 76 194 interfer radio mast emi case headed to court 12 16 09 03 37 PM and from the original article from The Standard newspaper Supreme Court Date Set by Steve Hynes Nov 23 2009 T OLS S am hip www standard net au story 40348 supreme court date set Ga Interference Stymies Radio Test The BBC has released a report on its year long test of digital medium wave DMW radio or digital radio mondiale DRM radio that is reported to offer a more robust signal that carries for greater distances than analog radio broadcasting T
103. t to date while delivering the detailed information comprising the electric field The FA7000 series of field analysers are based on an innovative approach that uses an isotropic field sensor to sample the composite field and transmit its amplitude digitally over optical fibre to a processor unit They represent a whole new way to more accurately measure modulated and CW electric fields in both conventional and reverberation chambers and allow the user to see the modulation envelope Accuracy and Speed you never thought possible For more information visit www arworld us or call us at 215 723 8181 www ar europe le In UK contact AR UK www uk ar co uk or call 441 908 282766 ISO 9001 2008 afr curope National Technology Park Ashling Building Limerick Ireland 353 61 504300 www ar europe ie W ww arworld us In Europe call ar United Kingdom 441 908 282766 ar France 33 1 47 91 75 30 ar Benelux 31 172 423 000 Copyright 2013 AR The orange stripe on AR products is Reg U S Par amp TM Off
104. the external contact energizing the relay slowly opens the stored inductive energy in its 25 H operating coil raises the voltage across the contact until it arcs over and the DC current resumes This scenario keeps repeating until the external contact has opened far enough so that the arcing stops But now the stored energy in that relay coil is released to charge the stray capacitance of the relay panel wiring connected to the positive terminal of the HFA coil Now the rise time was much faster 5 nanoseconds vs 75 ns to a peak of 4 kV vs 2 5 kV and lasted longer 1 minute for each polarity versus 2 seconds Even more troublesome was that some of the Zener diodes that had been used in relays as mini transient suppressors of the oscillatory SWC test did not conduct fast enough to dissipate the energy in the fast transient voltage wave form and partially punctured This created a high resistance leakage path and successive fast transients created more paths until the Zener failed thermally from excessive heat from the leakage current This failure mode was difficult to diagnose as the thermal failures occurred hours or days after the last fast transient The fast transient oscillatory SWC test was added to IEEE standard C37 90 1 in 1989 This 4 kV test voltage is required whether the installation is indoor or outdoor Note IEC 602555 26 reduces the test level 50 for indoor installations Taken from Survival of the F
105. the other terrible twin of low frequency conducted emissions with 61000 3 2 It is a product family standard applying to everything that can be connected to the public electricity supply and draws up to 16 A per phase What it limits are voltage changes reductions only due to inrush current and load current fluctuations especially repetitive fluctuations that can cause lighting to flicker A special measuring system is required to evaluate this the flickermeter specified in IEC 61000 4 15 IEC TR 61000 3 4 This deals with harmonic current emissions for products drawing more than 75 A per phase It is advisory because the connection of such products to the public supply always involves negotiation with the network operator Before IEC 61000 3 12 was produced it applied to products drawing more than 16 A per phase IEC TS 61000 3 5 This is a Technical Specification of the type that is not intended to be converted to a standard It deals with the same subject as 61000 3 3 but for products drawing more than 75 A per phase The precise reason why it is a TS and not a TR is obscure but as for TRs it cannot be notified under the EMC Directive in Europe IEC TR 61000 3 6 This Report is about harmonic emissions directly into the Medium Voltage MV High Voltage HV and Extra High Voltage EHV networks It is advisory because all such connections of loads are negotiated with the network operator IEC TR 61000 3
106. the transformer s enclosure which can be reduced by appropriate transformer design techniques if necessary This is the same scheme that is sketched in Figure 7 12 3 and is also merely Figure 7 13 2 with an isolating transformer attached in series with its mains input Where a power converter is connected to a high voltage power distribution network with its own dedicated co located step down isolating mains transformer our work is already done The HV distribution network is floating and on the other side of the step down transformer the power converter and its filters and any shielded cables can be directly RF bonded to the local earth ground structure and use it as an RF Reference as discussed above and shown in Figure 7 12 3 Sorry but I feel the need for a little tirade on earthing grounding jargon before I can leave the issue of filtering converters that are run from floating supplies Looking again at Figure 7 13 3 we see that it shows stray capacitances to the earth ground but no actual connections No electromagnetic noises generated by the electrical activities in electronic circuits have ever been reduced or eliminated by connecting them to an earth ground electrode The earth ground is not a sink for noise and it never has been and never can be The concept of diverting noise currents so that they are absorbed in the earth ground is simply a misunderstanding and a myth Anyone who ever got rid of noise
107. to suppress DM and CM noise emissions to the mains network It is important that it continually charges a The EMC Journal January 2013 battery or other electrical energy store such as a supercapacitor and from that battery or whatever voltage synthesises the AC power to drive our converter One or both of these mustinclude a safety isolating LF or HF transformer Battery The AC Charger 50Hz inverter Synthesised mains power AC DC DC AC AC power supply distribution power to the power network power converter converter converter Battery and or supercapacitor fuel cell or other energy storage device NOTE Batteries need regular maintenance and safe ventilation for flammable hydrogen gas NOTE Where a UPS is powering critical equipment or any equipment for a long time it is important to use a type that will be reliable enough Figure 7 12 8 Overview of a double conversion continuous conversion UPS The UPS s battery charger circuit AC power generator circuit or both must contain an LF or HF isolating transformer Like the LF isolating transformers discussed earlier and the HF isolating transformers discussed in Section 4 in 64 their effectiveness for suppressing CM emissions depends on their design and construction with special high frequency high isolation techniques being available often at extra cost DM suppression is achieved by passing all the power via the battery or other
108. trict limits because of the large proportion of the network load that is due to lighting while Class D applies to computers and TV sets which unless they include mitigation measures draw current from the mains supply as short pulses whose low odd order harmonic currents are almost in the same phase for all products so add arithmetically The 3rd 9th 15th etc add in the neutral wire of 3 phase and neutral distribution cables and can cause severe overheating theoretically the current can be 2 8 times the fundamental current The 5th harmonic propagates into the Medium Voltage network where it can excite resonance which is very bad news for system overvoltage and reliability Classes A B and D have each their own set of limits but Class C doesn t for some lighting products the class A limits apply for others the class D limits and for yet others either a special set of limits or a special current waveform So there aren t unambiguous Class C limits as such one has to refer to table 1 table 2 table 3 or special waveform The measurements involve quite a lot of data processing so a special harmonic analyser is required described in IEC 61000 4 7 Current work on this standard includes a series of amendments to take new technology into account notably LED lamps and new types of dimmers which are new and controversial issues The EMC Journal January 2013 IEC 61000 3 3 This is
109. ts ICs used on the printed circuits boards PCBs that resulted in them having lower noise margins This example of an EMC incident was previously reported in 110 which adds no more information to that given above Transformers aren t the only mains isolation technique others that are commonly used include motor generator sets and certain kinds of uninterruptible power supplies UPSs which can both reduce emissions of CM and DM noises into the mains power distribution networks M G Sets provide a very high degree of CM isolation between their input and output circuits due to their large physical separation and with careful segregation of their input and output cabling and the equipment connected to them and their cabling could achieve high CM impedances to tens of MHz They also provide a very high degree of DM isolation something that a transformer cannot do To be effective in reducing DM and or CM emissions UPSs must be isolating continuous on line double conversion types UPSs are marketed using a wide variety of technical sounding marketing terms some of which are proprietary and most all of which create the impression of much more technical capability than we actually get when we purchase them So I have found that it is best to completely ignore all marketing hype and instead focus on the products detailed technical descriptions Figure 7 12 8 shows a simple block diagram of the type of UPS that is needed
110. ts fibre optical delay line technology Eastern OptX provides an efficient solution to the market where transmission delays are required without having the need to perform these tests in real field situations The fibre optical technology has a many great advantages one of the most important is the Chomerics Europe a division of Parker Hannifin has appointed Tiberius Recean to the position of Automotive Specialist 44 year old Recean has worked for Chomerics Europe for six years as a Territory Sales Manager in Germany The creation of the new role is in recognition of the growing importance and relevance of shielding and thermal management materials to the automotive market As the magnitude variety and complexity of electronic systems on passenger vehicles continues to increase so does the need for advanced and innovative materials to manage EMI RFI and heat such as those developed and manufactured by Chomerics enormous bandwidth 40 GHz in which signals can be delayed This allows users of broadband systems such as frequency hopping or wide band multi channel radar systems to receive delay and retransmit the received signal without tuning replication systems As most fire and control radar systems are looking for incoming targets the Eastern OptX delay lines can be fitted with Doppler modulators that provide the reflected pulse with a simulated speed Without this option many of these systems neglect echoes As the t
111. very 15 minutes The meter is available in two models NIM 511 and NIM 513 The NIM 511 has a broad frequency range of 300kHz to 100MHz making it suitable for virtually all equipment operating at ISM industrial scientific and medical frequencies The NIM 513 operates over the The EMC Journal January 2013 narrower range of 10 to 42MHz encompassing the ISM frequencies of 13 56MHz and 27 12MHz which are widely used for semiconductor processing equipment heat sealers and induction heaters With an LED backlit 1 5in LCD display the meter will operate for about 22 hours on a charge of its NiMH batteries It is supplied with a hard case power supply and shoulder strap For further information visit www linkmicrotek com and www radhazonline com Tel 44 0 1256 355771 sales linkmicrotek com www linkmicrotek com Vectawave sets up worldwide sales channels Vectawave Technology Ltd has been designing and manufacturing power amplifiers for over 15 years Until recently most of their production was distributed through third parties In 2011 12 Vectawave invested heavily in a purpose built factory equipped with cutting edge design build and test facilities and are now in a position to offer amplifiers directly to the market under the Vectawave brand Vectawave s core product is a range of air cooled Class A broadband RF power amplifiers for use in industrial military and medical applications The range cov
112. voltages low as well as high present across the relevant components or a margin should be incorporated with respect to the LF emissions limits For a single component filter a 50 loss of capacitance will result in a degradation of attenuation of 6dB For conducted immunity over testing by a factor of 2 applying 20V rather than 10V for instance would be needed One consequence of using a capacitor with a high VCC in an AC circuit particularly for instance an X7R capacitor as an X or Y rated mains filter component 1s that the filter attenuation will be modulated by the AC voltage This effect of course would be hard to disentangle from other sources of 100 120Hz modulation in the power supply noise signature Also for multi voltage DC supplies such as 12 24V vehicle or marine applications the VCC change could cause a filter to have substantially different characteristics at the different supply voltages again hard to separate from other causes of variation If your aim is only to control radiated emissions above 30MHz by applying filter capacitors to cable interfaces then the pressure is less since capacitance value is usually less critical but as Figure 4 shows capacitors in the range 1 10nF can expect to have self resonances in the range from 30 to 200MHz which is the danger zone for cable coupling It may well be that the self resonance is especially and perhaps unexpectedly effective at stopping a particular
113. xternalPortalWEB ShowProperty BEA 20Repository Rules amp Guides Current 150_CtrlofHarmonicsinElecPowerSystems Pub150_ ElHarmonics 64 EMC Design of High Frequency Power Switchers and Choppers Design techniques for HF isolating transformers Keith Armstrong The EMC Journal Issue 95 July 2011 available from the archives at www theemcjournal com 66 EMC Design of High Frequency Power Switchers and Choppers Design techniques for high frequency HF output rectifiers Keith Armstrong The EMC Journal Issue 97 November 2011 available from the archives at www theemcjournal com 72 EMC Design of High Frequency Power Switchers and Choppers Suppressing RF emissions from converter inputs and outputs Keith Armstrong The EMC Journal Issue 98 January 2012 pages 27 38 available from the archives at www theemcjournal com 84 EMC Design of High Frequency Power Switchers and Choppers Suppressing RF emissions from converter inputs and outputs Keith Armstrong The EMC Journal Issue 99 March 2012 pages 30 42 available from the archives at www theemcjournal com 85 Fundamentals of EMC Design Our Products Are Trying To Help Us Keith Armstrong Interference Technology Magazine 04 03 2012 www interferencetechnology com fundamentals of emc design our products are trying to help us 3 92 EMC Design of High Frequency Power Switchers and

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