The Engineer’s Guide To Global EMC Requirements: 2007 Edition Written by: Roland Gubisch, Chief EMC Engineer and Bill Holz, GMAP Program Manager, Intertek Intertek Testing Services NA, Inc 70 Codman Hill Road, Boxborough, MA 01719 email@example.com 800-WORLDLAB www.intertek-etlsemko.com
Engineer’s Guide to Global EMC RequirementsTable of ContentsIntroduction……………………….……………………………………….2Background………………………………………………………………..2EMC as a mandatory compliance requirement………………………....3Regulatory compliance procedures………………………..……………..4Regulatory compliance frameworks……………………………………...4Authority Having Jurisdiction over EMC………………………………….6 Americas…………………………….……………………………..6 US………………………………………………………….7 Canada……………………………………………………8 Brazil………………………………………………………9 Europe……………………………….……………………………10 EU…………………………….…………………………..10 Russia……………………………………..………………11 Far East…………………………………………………………….12 Japan………………………………………………………12 China (PRC)……………….………………………..……..14 Chinese Taipei…………….……………………………....15 Conclusion………………..………………………………………..16www.intertek-etlsemko.com 1
Engineer’s Guide to Global EMC RequirementsIntroductionEngineers everywhere would like to test their products only once for electromagneticcompatibility (EMC), using a single set of standards and placing a single mark on theproducts to allow them to be sold around the world. Unfortunately, that aspiration will notbecome reality any time soon. If anything, it is becoming even more elusive as companiespursue new global sales opportunities further afield. The challenges are no longer technical;increasingly, they are raised by regulators in government offices many time zones away.The task of EMC testing for global markets is challenging indeed. Each country or regionretains its right to determine: • If EMC is a mandatory compliance aspect that must be met prior to placing products on the market • Identification of the authority that will have jurisdiction over regulating EMC • Determination of the technical requirements that must be met - whether emissions only (EMI), or both emissions and immunity (EMC) • Identification of the standards required • Compliance procedures and filings • Determination of what test reports will be accepted • Specification of any marks that must be applied.This paper will review the regulatory issues of EMC compliance in selected regions aroundthe world.BackgroundEMC issues have been around since the early days of telegraphy and radio. Interferencefrom solar activity caused “phantom telegraph operators” – telegraph output with notelegraph input – on long parallel transmission wires. The cure for this condition wasoccasional twists in the wires, which led directly to today’s high-speed twisted-pair LANwiring.With the increasing popularity of broadcasting, and then with the use of electronicequipment in commercial and military applications, rules to prevent radio interference andequipment malfunctions became necessary. The result has been a succession of EMCstandards and regulatory procedures worldwide. Some of the milestones are: 1844 Morse: telegraph 1892 Law of telegraph in Germany (EMC) 1895 Marconi: first radio transmission 1927 German Hochfrequenzgerätegesetz (High frequency device laws) 1933 CISPR founded as a special committee of the IEC, dealing with interferencewww.intertek-etlsemko.com 2
Engineer’s Guide to Global EMC Requirements 1934 US Communications Act; FCC is established 1972 Altair 8800: first personal computer (PC) 1979 FCC Part 15, subpart J (digital devices) 1985 IEC CISPR 22 (Information Technology Equipment - ITE) 1989 EMC Directive, EU; mandatory 1-1-1996.Personal computers and other microprocessor-based devices have triggered similaremissions standards around the world: 1979 FCC Part 15, subpart J 1985 IEC CISPR 22 1985 VCCI rules in Japan 1988 Canada Radio Act 1996 Australian EMC Framework 1997 Taiwan ITE EMI 1998 Korea ITE EMC 2000 Singapore EMI for telecom equipmentEMC as a mandatory compliance requirementThe first task is to identify the countries in which your company’s products are to be sold.Then you need to determine what EMC compliance requirements (if any) must be metbefore the products can be marketed in those countries.The overall scope of your efforts will be determined by the number of countries in whichyou wish to sell your products, of course. However, to keep this paper manageable – whileproviding a flavor of the issues to be encountered - we will limit the list to the followingregions: Americas: • United States (US) • Canada • Brazil Europe • European Union (EU) • Russia Far East • Japan • Chinese Taipei (Taiwan) • People’s Republic of China.Let’s assume that with all of its products, your company always carries out complete EMCtesting for the US and EU. Is that enough to allow you to place products everywhere in thewww.intertek-etlsemko.com 3
Engineer’s Guide to Global EMC Requirementsworld? Unfortunately, it is not. Many countries that require EMC compliance also imposeadditional hurdles to market entry in terms of deviations to international standards, in-country testing or country presence. Fortunately, there are also simplifying arrangementsand agreements that can leverage your EMC testing to cover larger geographical or marketareas. They are found under the broad umbrella term MRA (Mutual RecognitionAgreements or Arrangements).Regulatory compliance proceduresCountries or regions that regulate product EMC will typically employ one or more of threeprocedures to determine compliance with national or regional requirements. The particularprocedure may depend on product type. • Verification – the product is tested to the applicable EMC standard(s) and brought to market bearing appropriate regulatory marks and/or statements under the vendor’s or importer’s authority (the “responsible party”). • Declaration of Conformity – the vendor or other responsible party declares conformity of the product to the relevant standard(s). Some jurisdictions require accredited testing (US) while others do not. The product may then need to be registered with the regulator (Australia, for example) or not (US for EMC). Regulatory marking and user information are a part of the process. • Certification - the test report from an accredited or recognized laboratory, along with other technical information about the product, is presented to an independent third party for examination against the requirements. If the product complies, it is certified and listed with the regulator. The product may bear the certifier’s mark. Product surveillance may also be a part of the certification process.It’s not always easy for the regulatory compliance engineer or manager to determine theapplicable standards, compliance procedures and contact information for each targetcountry or region. Fortunately, there are simplifying frameworks to lighten the burden .Regulatory compliance frameworksMutual Recognition Agreements or Arrangements (MRAs) are multilateral agreementsamong countries or regions which facilitate market access for signatory members. MRAscan cover the mutual recognition of product testing, certification or both.However, the existence of an MRA does not imply harmonization of the standards amongthe participants. For example, the interpretation of appropriate Class A or Class B emissionlimits in a commercial environment can differ between the US and the EU, as reflected intheir respective standards and illustrated below:www.intertek-etlsemko.com 4
Engineer’s Guide to Global EMC RequirementsSome of the terms common to existing MRAs include: Agreement: Binding on participating parties Arrangement: Voluntary participation CAB: Conformity Assessment Body. A CAB can be either a tester or a certifier or both. In the case of US Telecommunication Certified Bodies (TCBs) and Canadian Certification Bodies, the certifier must also be an accredited test lab. The accreditation criterion for testers is ISO 17025 and for certifiers it is ISO Guide 65. Phase I: The MRA partners agree to recognize each other’s test reports Phase II: The MRA partners agree to recognize each other’s test reports and certifications (where needed).One of the better-known MRAs is the agreement between the European Union and the UScovering EMC, radio, telecom and several other product sectors. It has become a model forsubsequent MRAs. Other MRAs in operation or pending that cover EMC and telecominclude: Canada: With EU In APEC Tel In CITEL With Switzerland With Korea US: With EU With EEA EFTA (Iceland, Norway, Liechtenstein) With Japan In APEC Tel In CITELwww.intertek-etlsemko.com 5
Engineer’s Guide to Global EMC Requirements European Union: With US With Canada With Australia With New Zealand.Participating members of CITEL include Argentina, Brazil, Dominican Republic, Guatemala,Ecuador, Honduras, Mexico, and Paraguay. Participants in the APEC Tel MRA includeAustralia, Canada, Chinese Taipei (BSMI), Chinese Taipei (NCC, formerly DGT), Singapore,Korea, and Hong Kong.MRAs are allowing testing and certification by CABs in one region or country to beaccepted in another region or country − facilitating market access without additional testing.Regarding EMC, this is especially important when the destination country requirescertification as a regulatory requirement.Authority Having Jurisdiction over EMCAs you investigate each country to determine which agency has the EMC authority for yourproducts, you should also be able to determine what those requirements are. Around theworld, RF emissions or EMI is regarded as a potential threat to broadcast reception and tosensitive services such as radio navigation and radio astronomy. Therefore the spectrum orradio regulator in each country or region is usually charged with the widest responsibilityfor controlling EMI. Immunity, on the other hand, may be reserved as a performance issuefor critical applications such as medical or military – and the regulator may differ in eachcase. The combination of EMI and immunity as EMC may also be used as a means toestablish uniform trade rules across a region, as it is in the EU. The following is a briefoverview of what you need to consider as you investigate the requirements for eachcountry. We will use the US as a detailed example.AMERICASUS • The Federal Communications Commission (FCC) establishes the compliance regulations for radios, digital devices and other unintentional radiators. It does not regulate immunity, except in a few special cases. Typical emissions standards are Parts 15 (RF devices) and 18 (ISM equipment). Some applications of digital devices are exempted from the FCC’s technical standards, as is the case with test equipment, transportation vehicles, appliances, utilities or industrial plants. In many cases, such exempted equipment comes under the jurisdiction of other authorities, as noted below. Approval procedures: Verification for most unintentional radiators. No lab accreditation required. Some devices require Declaration of Conformity (DoC) and testing by an accredited lab in the US or MRA partner country. Some unintentionalwww.intertek-etlsemko.com 6
Engineer’s Guide to Global EMC Requirements radiators may be optionally certified by TCBs. For certification testing, the lab must be accredited and listed with the FCC either separately or through an accreditor. • The Food and Drug Administration (FDA) Center for Devices and Radiological Health (CDRH), designates consensus device standards for medical devices. Typical EMC standards include: IEC 60601-1-2:2001+A1:2004 (general medical EMC); FDA MDS- 201-0004 (1979) (EMC for medical devices); and ANSI / RESNA WC/Vol. 2-1998, Section 21, (Requirements and test methods for electromagnetic compatibility of powered wheelchairs and motorized scooters). Approval procedures: EMC report is submitted as part of device 510(k) filing, to FDA or an FDA-accredited person. • Department of Defense (DoD), for military EMC. A common EMC standard is MIL- STD-461E (1999) Requirements for the control of electromagnetic interference; characteristics of subsystems and equipment. Approval procedure: EMC testing can be witnessed by DoD inspector; lab accreditation is helpful. • Telecom network EMC varies by telecom network operator (ATT, Verizon, etc.), but most EMC requirements are based on GR-1089-CORE (2002) Electromagnetic compatibility and electrical safety – generic criteria for network telecommunications equipment. Approval procedure: EMC accreditation to GR-1089-CORE sections 2-4; network operator witnesses or accredits; equipment vendor submits test report to network operator. • RTCA, for aircraft and equipment EMC. The standard RTCA DO160D Environmental conditions and test procedures for airborne equipment includes both EMC and environmental requirements. This standard is harmonized with the European EUROCAE ED-14D. Approval procedure: EMC report is submitted to FAA (Federal Aviation Authority); lab accreditation is helpful. • SAE (Society of Automotive Engineers) EMC standard series J551/x, J1113/x is a start. However, the individual auto manufacturers (Ford, GM, DaimlerChrysler, Toyota, etc.) have their own EMC standards that differ from the SAE’s standards. Approval procedure: EMC report is submitted by device vendor to auto manufacturer; lab accreditation is important.This presents a fairly complex picture of regulations and regulatory authorities for EMC inthe US. The table below summarizes some of this EMC information in a convenient formatfor comparison with other jurisdictions.Jurisdiction United States - EMCwww.intertek-etlsemko.com 7
Engineer’s Guide to Global EMC RequirementsProduct type ITE Radio Appliance MedicalAuthority FCC FCC FCC exempt FDA/CDRH EMI only:Approval Verification Certification N/A CertificationProcedures DoC: accredited Cert: accreditedIn-countrytesting No No N/A Norequired?MRA with N/A N/A N/A N/AUS? For DoC only:Marks None N/A N/A FCC logoCanada • The regulation of EMC in Canada is similar to that in the US. Industry Canada (IC) establishes the compliance regulations for radios, digital devices and other unintentional radiators. Typical emissions standards are ICES-003 (ITE) and ICES-001 (ISM equipment). Some applications of digital devices are exempted from IC technical standards, in a manner similar to the FCC. In many cases, such exempted equipment falls under the jurisdiction of other authorities, as noted below. Approval procedures: Verification for all unintentional radiators. No lab accreditation required. • Health Canada (HC) designates consensus device standards for medical devices. It recognizes IEC 60601-1-2:2001+A1:2004 (general medical EMC). Approval procedures: EMC report is submitted as part of license application to HC. Class I device manufacturers require an establishment license; Class II, III and IV devices require a medical device license.Jurisdiction Canada - EMCProduct type ITE Radio Appliance MedicalAuthority Industry Canada Industry Canada IC exempt Health CanadaApproval EMI only: Certification N/A LicensingProcedures VerificationIn-countrytesting No No N/A Norequired?MRA with Yes, Phase I Yes, Phases I & II N/A Nowww.intertek-etlsemko.com 8
Engineer’s Guide to Global EMC RequirementsUS?Marks Label info only Label info only N/A N/A Brazil • The National Institute of Metrology, Standardization and Industrial Quality (INMETRO) is the authority with jurisdiction over the general safety of products as well as EMC. There are very few general products that require safety for INMETRO certification and none that require EMC at this time. • Radio and telecom products are certified and homologated (an administrative approval) by the National Telecom Agency (ANATEL) and EMC is a factor in the approval. Both emissions and immunity compliance are required for telecom equipment; the standards reference IEC. Many but not all of the rules for short- range radio devices are identical to FCC rules. • The National Health Surveillance Agency (ANVISA) is the authority for medical equipment; EMC is also required.Jurisdiction Brazil - EMCProduct type ITE Radio Appliance MedicalAuthority INMETRO ANATEL INMETRO ANVISAApproval Certification and N/A N/A RegistrationProcedures HomologationIn-countrytesting N/A Yes N/A Norequired?MRA with Pending Pending N/A N/AUS?Marks no no N/A N/AEUROPEEUWith 27 member states, the population and economy of the EU exceeds that of the US. TheEU has simplified the process of access considerably by identifying the “essentialrequirements” for almost everything that is placed on the market in the EU. The authoritieshaving jurisdiction vary by product type, and each country has a Competent Authority foreach product type or directive. For example, the Competent Authority for EMC in the UK isthe Department of Trade and Industry (DTI). The specific “essential requirements” for yourproducts will be listed in the directives that apply to your product. In most cases, thewww.intertek-etlsemko.com 9
Engineer’s Guide to Global EMC Requirementsdirectives will be “New Approach” directives for which CE marking signifies compliance andthe applicable standards have been published in the Official Journal of the European Union.A good place to start for guidance on directives and standards ishttp://www.newapproach.org. The CE marking indicates that the equipment bearing themarking complies with all of the applicable “New Approach” directives. • Most electrical/electronic products must comply with both emission and immunity requirements, according to both the current EMC Directive 89/336/EC and the new EMC Directive replacing it, 2004/108/EC. This includes appliances and many devices exempted from EMI regulation in the US and Canada. In addition, the safety standards for household appliances now require compliance with limits to the surrounding low-frequency electromagnetic fields according to EN 50366. This is a safety standard, not an EMC standard. • The “essential requirements” for radio and telecom equipment under the R&TTE Directive 1999/5/EC include electrical safety according to the Low Voltage Directive (but with no lower voltage limit), RF exposure for radio transmitters and EMC according to the EMC Directive. For telecom terminal equipment, there are no more requirements. Radio transmitters must also comply with requirements for efficient use of the spectrum. Both spectrum and EMC standards for radio equipment are published by ETSI, the European Telecommunications Standards Institute. • Medical devices are approved according to a classification scheme originating with the Medical Device Directive 93/42/EC and used as the prototype for other medical device regulations around the world, including Canada. The basic medical EMC standard is EN 60601-1-2:2001. The EMC requirements are modified by specific standards EN 60601-2-x to define particular test setups or higher or lower limits for particular EMC phenomena. EMC is also a factor for in vitro diagnostic medical devices (Directive 98/79/EC) and active implantable medical devices (Directive 90/385/EEC).Jurisdiction European Union – EMCProduct type ITE Radio Appliance Medical Spectrum EMC Medical EMC CompetentAuthority Competent Competent Competent Authority Authority Authority Authority Verification, Verification. Verification. DoC, TypeApproval Notified Body Notified Body Verification Examination,Procedures opinion may be opinion may be Notified Body obtained rendered. approvalIn-country No No No Notestingwww.intertek-etlsemko.com 10
Engineer’s Guide to Global EMC Requirementsrequired?MRA with Yes, Phases I & II Yes, Phases I & II Yes, Phases I & II Yes, Phases I & IIUS? CE, possibly CE and Notified Notified BodyMarks CE CE Body number number, alert where applicable markRussia • The authority having jurisdiction for general product types is GOST, short for Gosstandart (State Committee for Quality Control and Standardization). It is the national standardization body in Russia. More then 60 EMC standards have become mandatory. Basic standards are harmonized with IEC and CISPR standards. The Harmonized Tariff Code (HTC) is the determining factor if EMC applies to your products. If your product requires EMC compliance, testing can be done in Russia or at accredited labs located outside of Russia. It is also possible (based on agreements) to utilize EMC test reports to the EU standards from accredited labs. If your product requires the GOST mark, both safety and EMC are included under the single mark. You will also need to determine whether any special warning statements need to be included in the user manual and on the packaging, along with any specific language requirements. • The authority for radio equipment in Russia is Glavgossvyaznadzor (Main Inspectorate in Communications). The application (with a detailed list of telecommunications equipment) should be submitted to the Certification Department of Goskomsvyaz (State Committee on Telecommunications and Information of the Russian Federation). The Department carries out a preliminary analysis to determine whether the equipment is compatible with the telecommunications technology currently used in Russia. After this technical review, two designated certification laboratories (of the 43 located across the country) will test the equipment "on type" and also for quality assurance. This will involve testing in the field and at the manufacturers site. If the test results are successful, a Goskomsvyaz Certificate is issued and is valid for up to three years. Radio equipment sellers must obtain an additional permit from Gossvyaznadzor (The Russian Federation State Telecommunications Control) of the State Commission on Radio Frequencies (GKRCh) to use the radio spectrum and specific equipment on a specific frequency band in a specific area of Russia prior to the certification process. • The Federal Service for Control over Healthcare and Social Development (Roszdravnadzor) is the main government agency responsible for registration of medical equipment, including foreign-made equipment. Applications for registration can include certificates of compliance obtained from other jurisdictions, such as:www.intertek-etlsemko.com 11
Engineer’s Guide to Global EMC Requirements o ISO 9001, ISO 9002, ISO 13485, and ISO 13488 certificates which should be notarized in the country of origin. o Certificates of registration of medical equipment issued by a respective government agency in the country of origin, such as FDA certificates, EC Certificates (CE Mark) and Declaration of Conformity. All such certificates should be notarized in the country of origin. o Electrical safety and EMC (electromagnetic compatibility) certificates, The Russian EMC standard corresponding to IEC 60601-1-2 is GOST R 50267.0.2.Jurisdiction Russia - EMCProduct type ITE Radio Appliance MedicalAuthority GOST Glavgossvyaznadzor GOST RoszdravnadzorApproval Certification, Certification Verification RegistrationProcedures licensingIn-countrytesting No Yes No Yesrequired?MRA with No No No NoUS?Marks GOST-R No GOST-R NoFAR EASTJapan • The Ministry of Economy, Trade and Industry (METI) is responsible for appliance safety, including RF emissions (EMI). Immunity is not required. In 1999, the Electrical Appliance and Material Control Law was revised to become the Electrical Appliance and Material Safety Law (current law), which was implemented on April 1, 2001. Products subject to regulation are mandated to be labeled with the PSE mark. A wide range of products can be self-verified to the requirements and carry no regulatory marking. The RF emissions limits established for appliances are similar to corresponding CISPR standards, although deviations exist. • EMI from Information Technology and Telecom equipment has been handled by a private, non-governmental, membership-based Voluntary Control Council for Interference by Information Technology Equipment (VCCI). The VCCI labeling has become so well accepted in some domestic markets that it has become a de facto regulatory gateway. With the new US/Japan Telecom MRA signed in February 2007, access to VCCI labeling will be available through either the membership route or by local accreditation to the VCCI standards based largely on CISPR 22.www.intertek-etlsemko.com 12
Engineer’s Guide to Global EMC Requirements • The authority for radio regulation in Japan is the Ministry of Internal Affairs and Communications (MIC). The technical requirements are contained in Radio Equipment Regulations dating from 1950 and have been updated numerous times since. Radio rules published by private certification bodies such as TELEC, or by industry associations such as ARIB (Association of Radio Industries and Businesses), are not to be confused with the official MIC technical requirements, although they may all seem very similar. The MIC radio rules are similar to corresponding FCC rules but there are many differences, especially with regard to frequency allocations. • Medical products in Japan are regulated under the authority of the Ministry of Health, Labor and Welfare (MHLW). EMC requirements have been phased in over several years, with the last transition period for existing products just ended in March 2007 for Class I devices. The applicable EMC standard JIS T 0601-1-2:2002 corresponds to IEC 60601-1-2 first edition. This is soon being superseded by IEC 60601-1-2 2nd edition; the 2nd edition may be used currently with justification.Jurisdiction Japan - EMCProduct type ITE Radio Appliance MedicalAuthority MIC METI MHLWApproval Certification, Certification, Registration LicensingProcedures SDoC verificationIn-countrytesting No No No Norequired?MRA with Yes, 2007 Yes, 2007 No NoUS? Class B: VCCI mark TechnicalMarks Conformity PSE or none None Class A: Kanjii Mark textChina (PRC) • The People’s Republic of China (PRC) has enforced EMC regulations since 1999, largely emissions only. Under the Compulsory Product Certification System (CPCS) implemented in 2002 and under the authority of the Certification and Accreditation Administration of the PRC (CNCA), a number of listed product categories must carry the CCC certification mark. The CCC mark includes provisions for indicating safety (“S”) or EMC (“EMC”) or both (“S&E”). The implementation rules for compulsory product certification specify the applicable procedures and standards by productwww.intertek-etlsemko.com 13
Engineer’s Guide to Global EMC Requirements type, in a numbering format: CNCA-nnC-mmm:year. Examples are given in the table below. • Radio approvals are under the overall authority of the Ministry of Information Industry (MII). The State Radio Regulation Committee (SRRC) Certification Center, under the MII, is directly involved in the approvals. Mobile terminals, including cellular base stations and handsets, are classified as terminal equipment and are so regulated. Quality assurance is also part of the certification process. PRC radio standards are drawn from FCC, TIA and ETSI, including EMC requirements. • Many PRC standards are identical to international, FCC or ETSI standards. For example, the PRC standard GB4343 is equivalent to CISPR 14, and GB9254 mirrors CISPR 22. The IEC standards IEC 61000-3-2, -3-3 and 61000-4-x are references. Unfortunately, only in-country testing is permitted at this time. • Medical devices fall under the authority of the State Food and Drug Administration (SFDA) and optionally the Ministry of Health (MOH). Medical devices are classified according to risk (I = lowest, III = highest) as with many other medical regulatory regimes. Implementation rules for medical products reference many IEC-particular medical electrical standards (IEC 60601-2-x). The SFDA requires type testing and factory audits.Jurisdiction People’s Republic of China - EMCProduct type ITE Radio Appliance MedicalAuthority CNCA CNCA CNCA SFDA, MOH Certification; see Certification; Certification; Certification;Approval see: CNCA-08C-032 see: see: to 043 forProcedures CNCA-07C-031 CNCA-01C-020 CNCA-01C-016 examples; also for examples RegistrationIn-countrytesting Yes Yes Yes Yesrequired?MRA with No No No NoUS?Marks CCC CCC CCC CCCChinese Taipei (Taiwan) • The authority for safety and EMC for a wide variety of appliances and equipment in Taiwan is the Bureau of Standards, Metrology and Inspection (BSMI). RF emissionswww.intertek-etlsemko.com 14
Engineer’s Guide to Global EMC Requirements (EMI) are regulated. Safety and EMC standards are derived from the IEC. For example, the limits in CNS 13438 are equivalent to CISPR 22. • The National Communications Commission (NCC, formerly DGT) has authority over radio equipment. Many technical standards, especially for short range devices, are identical to FCC rules. • Taiwan’s Department of Health (DOH) regulates the importation of medical equipment. To market a medical device in Taiwan, the DOH pre-marketing registration approval must be obtained before the Board of Foreign Trade (BOFT) of the Ministry ofEconomic Affairs (MOEA) will issue an import license. The DOH, following many other economies, has grouped medical devices into three classes: I, II, III. EMC is required according to IEC 60601-1-2:2001, corresponding to the standard DOH-00003.Jurisdiction Chinese Taipei - EMCProduct type ITE Radio Appliance MedicalAuthority BSMI NCC BSMI DOHApproval DoC and Certification, Certification LicensingProcedures certification registrationIn-countrytesting No No No Norequired?MRA with Yes, Phase I Yes, Phase I No NoUS? Commodity CommodityMarks NCC No inspection mark inspection markConclusionThis paper has provided a quick overview of what is required to ensure that EMCrequirements are legally met for the countries in which you want to market your products.Although it is necessarily brief, it serves as a guide with which you can develop your ownlist of country requirements.As you expand your list, you will be able to weigh the challenge of meeting compliancecriteria and procedures for several nations simultaneously. Compliance has to be taken veryseriously; the penalties for not complying vary from simple quarantine of your products atcustoms to severe measures such as monetary fines and even imprisonment.www.intertek-etlsemko.com 15
Engineer’s Guide to Global EMC RequirementsIf global EMC compliance issues are a recent challenge for your company, or if your currentcompliance staff are stretched thin, it may be beneficial to partner with Intertek-ETL Semko,a proven leader in EMC test and certification worldwide. We have more than 322laboratories in 110 countries around the world, 20 of them in the US alone, In addition toMRA arrangements, we have special agreements with agencies and labs in many othercountries including Israel, Brazil, Russia, and Belarus.By working with a partner lab, it is easier to assemble a product- or technology-specific testand certification plan that maximizes your testing dollar and gives you the additionalresources needed to seek global compliance. You have the security of knowing that theplan is defensible in the face of management scrutiny and traceable in case of an audit.And it can be modified easily as technology and business structures change.For more information, go to www.intertek-etlsemko.com. Call 1-800-967-5352 or email firstname.lastname@example.org.Intertek gets you the answers you need—within 24 hours. We look forward to helping you.www.intertek-etlsemko.com 16
Insider’s Guide to Faster Safety & EMC Testing Intertek Testing Services 70 Codman Hill Road, Boxborough, MA www.intertek-etlsemko.com
IntroductionBringing a new product to market is a complex and involved process thatrequires the talent and expertise of a wide range of personnel within anorganization; business strategists, product designers and engineers, productionteams and line staff to name a few. Amidst the flurry of development activitywithin these teams, Safety and EMC product compliance issues may seem to bea low priority – at very least until a prototype is built. Indeed how can you testsomething for compliance when it doesn’t actually exist? By postponing compliance considerations until later inthe development cycle, it can cause delays in launchinga product to market. Testing can reveal non-conformities that require a product redesign ormodification then retest – lengthening the complianceprocess significantly. Indeed it is common thatmodifications made to a product for EMC compliancecan effect safety compliance. For example, having toadd extra insulation into a product can reduce thecurrent creepage and clearance distances required forsafety purposes, potentially making it unsafe. Similarly,changing bypass capacitors to comply with safetyleakage current requirements can throw off EMCcompliance. The product then has to be modified to fixthis problem and then retested for safety.With such a potentially complex situation, it seems obvious that product safetyand EMC compliance should be considered from the earliest concept stages ofdevelopment (and in an integrated way) to keep launch disruption to a minimum.Product modification and retest delays can have a critical impact on yourbusiness, potentially costing you thousands in lost revenue (missing out onHoliday sales for example) as well as damage to your brand. Your competitorscould get their rival products to market first, making them - in a consumers mindat least - a “leader” and everyone else that comes after a “follower”.In this document, we will explore some simple, practical strategies that ensurethese compliance considerations can be addressed early, and enable thecompliance process itself to be optimized to help reduce time to market, costs,chances of delay and the likelihood of having to make frustrating modificationsand retests to your product.
Knowledge is PowerIt is a cliché to say knowledge is power, yet despite that, it is true.When a company decides to expand its portfolio of products, the first thing doneis market research. Is the product needed/wanted in the marketplace? What arethe competitive products, and what are their weaknesses? What features wouldmake the new product better than anything else available? What would its lifebe? Would it need to be repairable/upgradeable? Does it have to be functional oraesthetic or both? How much should it cost? And most importantly, to whom isthis product targeted and in which countries can it be sold? These last two items of information are essential knowledge for the development team, so try and get a copy of the market research for the proposed product. Depending on the depth of the research, this will give some indication as to any special Safety or EMC conditions that may have to be considered during the design (e.g. Is this product for home or commercial use; is it aimed at able-bodied users? Or children or the elderly?) and it will also show which regional regulations will have to be met.This knowledge is key to organizing the compliance schedule and budget itselfas you can use the existing knowledge of your engineers to identify the probableSafety and EMC test plan and likely costs – based on previous projects. Forexample, in the US, domestic products must be tested for EMC emissions, notimmunity. In Europe, domestic products must be tested for both. If your productis going to Europe, your test plan for compliance in this region is therefore likelyto take a little longer, cost a little more and will probably require more samplesand spares to be provided to the test house. These factors can then be built intoyour compliance plans, helping you to anticipate the requests of the test house,saving you time when you actually come to the testing stage.
Standards & Local DeviationsKnowing the safety and EMC regulations for a newproduct in the target market is essential for theproduct development team. This enables them toobtain appropriate Standards for those markets(indeed they can select Standards that give themmaximum geographical coverage) and design theproduct with the safety and EMC requirements ofthese Standards in mind.Standards & JurisdictionUS - FCC/ FDAUS/EU - FCC, IEC, CENELECAsia Pacific - FCC or IEC with deviationsProduct Jurisdiction StandardITE USA FCC Part 15, 60950-1ITE EU, Asia CISPR 22/EN 55022, CISPR 24/EN55024Medical USA, International IEC 60601-1-2Test/Measurement 61010-1Audio/Visual 60065Household Appliances 60335-1Electrical Tools 60745-1ISM USA FCC Part 18ISM EU, Asia EN 55011 +…Lab USA ExemptLab EU EN61326-xRadio USA FCC Part 15, 22, 24, 25, 27, 74, 90, 95Radio EU ETSI EN, EN 301 489 -x
Insider’s Guide to Faster Safety & EMC TestingPurposefully designing a product for safety and EMC conformity seems acautious and conservative approach to product design that restricts creativity andinnovation, but it is likely to reduce your chances of product failure at the testingstage.A Note on Standards Use Many companies maintain an in-house library of Standards that relate to their product ranges with a view to ongoing safety and EMC compliance within their target markets. These libraries can be extremely effective in aiding designers, but two issues need to be highlighted. The first is the matter of interpretation. Some of the language used in Standards – particularly inthose sections relating to specific tests to be conducted, can be interpreted in anumber of ways. Calling upon the expertise of a testing and certification partnerto interpret the fine detail of a Standard can help designers and engineersovercome the hazards of ambiguity and potential product non-conformity. If theissue has particular subtleties, your test partner can even approach theStandards Developing Organisation (SDO) directly for a definitive explanation.The second issue with in-house Standards libraries, is the need to maintain thelatest version of the Standard. When potentially dozens of Standards need to bemaintained, it is possible that an expiring document may be overlooked. Hereauditors and quality managers play their part in keeping the available documentsup to date – but again your testing and certification body can provide you with thelatest (and upcoming) Standards updates and information on local safety and orEMC deviations that might apply to a sub-section of your target market.Standards are expensive! But on the other hand, how expensive is it to re-work anon-compliant product design, or, how expensive is it to miss a product launchdate in the market place? Purchase of the standard is a good investment and isquite inexpensive when compared to the cost of re-submittal to the test lab.
Insider’s Guide to Faster Safety & EMC TestingUnderstanding Dates of Withdrawal (DOW) and Standard VersionterminologyEnsuring that you’re using the appropriate standard is an obvious thing, butunderstanding the validity of dates within those standards is critical to using theright one! It would be incredibly frustrating to commission product tests against aStandard in your library and then find that it is soon to expire and that any testingand certification will need to be revisited.The new version of the Standard my not require any additional tests to becompleted – it could be a something as simple as a new labelling requirement,but it could require product modifications and a re-test. Understanding how thedating information in Standards works could save you time and expense inhaving to revisit your test program soon after completion because the Standardthat was tested against is no longer the newest version.Outlined below are some brief explanations of critical Standard dates andterminology for standards in the EU:Approved DraftThe Approved Draft Date is usually found in the Foreword atthe front of the Standard. This date is essentially when theStandard text was “Approved” by CENELEC, prior topublication by the National Standards Bodies.DOP - Date of PublicationThe DOP or Date of Publication is the date by which the Standard must bepublished by all countries’ National Standards Bodies. The DOP is usually 6-12months after the document has been “Approved” by (for example) CENELEC andonce the document is published, it becomes the current version of the Standard.Amendment DatesAs you would expect, Amendments to Standards (also found in the foreword anddesignated with the letter A and numbered in sequence e.g. A1, A2 etc) alsohave an Approved Draft Date and a DOP, but in European Standards, you willalso find a Date of Withdrawal (DOW). This DOW indicates the date when theStandard it is associated with can no longer be used on its own - i.e. without thenew Amendment. DOWs are also found on fully re-issued Standards. It doesn’tindicate that the Standard as a whole will cease to be current on that date.
Insider’s Guide to Faster Safety & EMC TestingAmendment Numbers An interesting point to note is that Amendments are numbered in a specific way. Generally speaking a single number after an A, e.g. A1, A2, A3 etc indicates that an amendment applies to both IEC and EN versions of the Standards. However, if an amendment only applies to the European Standards - say in order to comply with a piece of European legislation then a two digit number will be used, e.g. A11, A12, A13 etc. Essentially ifyou have an A1 amendment and an A11 amendment in the same document -you haven’t missed amendments 2,3,4,5,6,7,8,9 & 10! - It’s just that there are twodifferent amendments to that Standard; one for International use, one forEuropean.BS, EN & IECThe name of a Standard will be designated with a BS, EN or an IEC. A BSdesignation indicates a British Standard, an EN designation indicates that it is aEuropean Standard and an “IEC” designation indicates a worldwide Standard.Part 1s and Part 2sMany Standards will be divided into part 1s and part 2s. Part one usually refers toa generic category of products - for example “Household and similar electricalAppliances” and gives details of general requirements for them and part tworefers to specific items in that category, say for example room heaters.REMEMBER!For certification purposes, a product can only be said to conform to a Standardthat is still current. For example if I test a product to a particular Standard andthen an amendment is published for it, my product will not comply with the mostcurrent (now amended) version of the Standard once the Date of Withdrawal onthat Amendment is passed.Similarly, if you have a Certification for a product that doesn’t expire for severalyears - but the Standard that was used to get that Certification gets Amendedbefore your certification runs out, you must contact your Certification Body toenable them to determine what you need to do to comply with the latest version
Insider’s Guide to Faster Safety & EMC Testingof the Standard. Sometimes you may need to do additional testing - sometimesthe conformity is purely a documentary exercise but you must ensure that yourproduct meets the most current version of the Standard.The Devil is in the Details: Designing for ComplianceContinue to use the knowledge and expertise of your product designers andengineers to “design for compliance”, but also use the available productStandards as design reference tools and even look at existing best of breedproducts to see how they have overcome certain design challenges.By establishing safety and EMC compliance as afundamental design goal, along with functionality,ease of use, aesthetics etc at the start of the designprocess, compliance issues can be tackled earlier inthe design cycle. Compliance will be seen as aproduction imperative not a last minute addition tothe project. This will reduce chances of productfailure at the test phase as the product itself will be“designed for compliance”.Issues to consider during the design phase: • Materials – knowing the characteristics of the materials that could be used in the product and how they behave in certain environments can help you choose materials that make optimum contribution to safety and EMC compliance • Printed Circuit Boards (PCBs) – Consider the architecture and positioning of PCBs for optimum protection • Ventilation – Keeping a product cool is important but will the venting enable EM radiation to seep out at unacceptable levels? Or bring instability to the system? • Shielding – by adding shielding to prevent EMC emissions, are you reducing the clearance of electrical components within the system? Will the extra material enable the system to overheat? • Family resemblance – Perhaps minimize the differences within suites of products if you want to minimize the testing they have to undergo. The
Insider’s Guide to Faster Safety & EMC Testing fewer the differences between them the less complicated (and costly) the testing will be. • Cabling – does the cabling have optimum shielding and protection? • Software and virtual testing – some immunity upsets can be corrected or mitigated by suitable operating software/firmware design. Also, consider the use of virtual testing software. A number of IT packages are available that can model and analyse a product design that can help designers design for compliance.Choosing ComponentsWhere possible use listed or certified components in critical systems in theproduct. e.g., controls, transformers, components in the 120 or 240 primarycircuit, etc (and know their ratings and conditions of use) as these will contributeto the overall compliance of your product.Also with some specific products – like UK plugs for example, having certifiedsub-systems like pre-approved moulded pin inserts means that some of yourtesting has already been done and you could save money on your overall testprogram. The temptation to use non-listed components because they are cheaper can be a false economy – they are likely to be unproven, and unless the manufacturer is reputable or at least already trusted by you, they could be of questionable quality. In addition, such non-listed components may require extensive additional evaluation and testing, including annual re-testing. Just remember if a batch ofcomponents (and even materials) seems a bargain that is too good to be true, itprobably is.A Note on Modifying Established ProductsIf you are redesigning or modifying an existing product, even if you are simplyswapping one component for another from a different supplier, don’t forget to tellyour testing and Certification/Approval partner, so they can determine if anyadditional testing is required. Swapping one component for another may haveimplications that weren’t anticipated when the substitution was made and if youdon’t notify your partner; it may invalidate your certification. Very often
Insider’s Guide to Faster Safety & EMC Testingsubstitutions have no impact on a product at all, and no further testing is needed,but it is important that documentation is updated with the change for auditingpurposes.Putting Pen to PaperDocumenting the design and production process is invaluable for the complianceprocess. Quality Management tools and Project Management systems provide auseful structure for capturing information that not only can it help an engineer re-trace their steps and identify a problem if a product shows a non-conformityduring the testing process, but it will also help them to keep track of componentsand schematics for easy reference – particularly if they are creating a suite ofproducts.The testing and certification team at yourpartner laboratory will require access tothe component and materials lists as wellas circuit diagrams and drawings in orderto be able to test and assess the product.Surprisingly, a great many testing andapproval projects get delayed, not becauseof the modification of product or because afailure of tests, but because the test labhasn’t had all of the paperwork they needto move a project forward. It seemsbureaucratic, but as test houses andcertifying bodies are regularly audited toensure the work they do is to a consistentand of high standard, they need to have allof the relevant documentation necessaryto conduct the work. Sometimes the mostsimple of required “paperwork” (usermanual, installation instructions, productmarkings, etc.) is not provided. If amanufacturer can have all of the relevantdocumentation ready for the test house,frustrating delays can be avoided.In your records, it is also beneficial to keep a list of contact names and numbersand email addresses for the team at the test lab, and some calendar notes tocheck in regularly with them to check on the project progress. Some
Insider’s Guide to Faster Safety & EMC Testingmanufacturers don’t do this as they want no part of the compliance process, butmany others have found an active dialogue with the test house and anunderstanding of and proactive involvement in the process can help reduce thetime it takes and reduces the number of potential issues that could arise.Design ReviewMany manufacturers have found it beneficial to have a design review conductedby their test or certification partner. This highlights any design issues early andcan be conducted using the circuit diagrams, component lists, design drawings –and if it is available, a prototype. Initial discussions with the certification partnercan even begin with an artists rendering or cardboard mock-up. If necessary theproduct can then be modified or re-worked before ever reaches the laboratory.Your partner will not only review the product but they can also be used as asource of reference for interpreting Standards.The Compliance Process Understanding the Safety and EMC and compliance process and actively preparing for and participating in it can help reduce the time it takes to complete it successfully. It is tempting to hand a product over to a test house, and take a “hands off approach” to compliance. Obviously your laboratory partner has both the expertise and the facilities to test a product to Standard and is fully capable of managing the process. However knowing the type of tests your product will undergo and where possible conductingsome preliminary testing yourself, can help give you some initial feedback onwhere your product might fail, enabling you to make appropriate modificationsbefore a product reaches the formal testing stage.
Insider’s Guide to Faster Safety & EMC TestingWhat can a man with a radio do?The most basic of all EMC tests – that you can conduct yourself withoutspecialist equipment or test chambers - is the radio test. Switch on your radioand hold it near your live appliance and see if the reception becomes distorted. Ifit does, it’s likely that your product needs better emissions mitigation.Other basic bench tests can usually be conducted at site with some help fromyour test laboratory team. They can give you direction on equipment you willneed, guidance on specific tests and even observe some testing so it can beincluded in the formal compliance assessment.Keep it in the FamilyWhen you are submitting products to the laboratory for testing, group them into afamily of products, and submit as many similar items as is feasible at the sametime. This will help to reduce the cost and time required for the complianceprocess for multiple items. If that isn’t possible then try and arrange a worst case(fully loaded) configuration that can represent the other units in the family.Partners Choosing to work collaboratively with a compliance partner like a test house or a certification body from the beginning of the design process can also bring clarity and speed. Particularly if a manufacturer’s design team has a thorough understanding of the compliance process and can prepare in advance for the requests of test house. As well a providing advice on what Standards should be referenced during the design phase and how to interpret them; they can also conduct design review and give general guidance throughout thedevelopment of where issues typically lay. This will help manufacturers toprepare their product for test and reduce the likelihood of failure.
Insider’s Guide to Faster Safety & EMC TestingConclusionIn a global market where the ability to innovate and respond to market needs withnew and vibrant products is the mark of world leading brands, time to market is akey factor in determining both the success of a particular product and ultimatelythe ongoing commercial success of a company. As each trading area in the worldhas its own set of specific regulations and requirements for these products,minimizing the time to meet these is critical to reducing time to market.To reduce the time it takes to complete the compliance process the manufacturercan: • Consider compliance issues from the beginning of the design process. These need to be an integral part of the creation of a new product, not an afterthought. • Use the knowledge and expertise available to them to ensure they are designing product to the latest versions of the Standard, and that they have taken into consideration the local deviations that may apply to their product. A test partner will be able to advise on what Standards to use, and if required, how to interpret them. • Improve their understanding of, and increase their involvement in the compliance process. By anticipating the needs of the test house, response and delivery times can be improved. • Design for compliance. Deliberately use appropriate materials, proven designs and approved components that provide adequate EMC shielding and reduce hazards from electrical shock. • Maintain a detailed technical file on the project – so when the test house makes a documentation request, everything required is quickly available. • Utilize a design review from their partner test house to ensure that they are on the right track and that any issues can be spotted and rectified early in the product development process.There is no magic solution to prevent all of delays with EMC and Safety testing.Sometimes products fail and sometimes delays occur for other reasons, but withthese simple, common sense efforts, they can at least be reduced. Designing forcompliance is an unromantic notion, but a common sense one. You can optimizethe testing process with proactive involvement, but a well designed product thatmeets all of the criteria required of it, will be the most influential factor in gettingthrough the compliance process, fast.
Why 50% of ProductsFail EMC Testing the First Time Intertek Testing Services NA, Inc. 70 Codman Hill Road, Boxborough, MA 01719 Phone: 800-967-5352 Fax: 978-264-9403 Email: email@example.com Web: www.intertek-etlsemko.com
SummaryA large percentage of electronic products fail to meet their target EMC requirements the first time they aretested. In this article we look at some of the possible reasons for that failure rate, and what designers andmanufacturers can do to improve the success rate and therefore time to market.Why do 50% fail?During the last several years, we have observed that initial EMC test failure rates for electronic productshave decreased gradually. Improved success may be the result of growing awareness of EMC designconsiderations, use of EMC software, reduced circuit dimensions or all of these factors. Nevertheless, wecontinue to see EMC test failure rates around 50%.Looking more deeply into the numbers, we note that, for example, medical products are slightly moresuccessful (~40% initial failure) at meeting their EMC objectives than information technology equipment(ITE). One might expect otherwise from the added performance constraints of the medical EMC standardIEC 60601-1-2 over the ITE standards CISPR 22 and 24, but two factors may work in favor of medicalproducts. They are often designed more conservatively and with more review than ITE, and the IEC 60601-1-2 standard it self allows justified derogations from the limits. But overall, the same basic EMCconsiderations apply to both medical and ITE. 60 Fortunately, the EMC learning curve for products that fail 50 ITE initially is quite steep. Presumably taking advantage of both the EMC education provided by the first go-around, as well 40 Medical as the pinpointing of EMC problems, manufacturers reduce 30 the failure rate on the EMC re-testing to the level of 5% - Learning curve – 7%. Very challenging products may require a third round of Failure 20 plus knowing exactly what EMC testing, for which we observe a failure rate reduced to 10 1% - 2%. 1st 2nd 3rd trialBased on our experiences with a wide variety of equipment suppliers, we can summarize the leadingobserved causes of initial EMC failure as: • Lack of knowledge of EMC principles • Failure to apply EMC principles • Application of incorrect EMC regulations • Unpredicted interactions among circuit elements • Incorporation of non-compliant modules or subassemblies into the final productThese topics are discussed briefly in the context of a product design and development program intended tomaximize the likelihood of success in the initial EMC testing.www.intertek-etlsemko.com 1
EMC regulationsAlthough RF interference considerations have existed since the advent of radio, commercial EMCregulations (both emissions and immunity) are relatively recent – and continuously changing. Equipmentdesigners and regulatory compliance engineers have to work hard to identify and keep abreast of the EMCregulations that impact their products. Of course, regulations should not be the only design driver.In the USA, the Communications Act of 1934 established the framework for resolving radio interferenceissues. Parallel laws were enacted around the world, with Germany providing early leadership in laws andstandards that provided a model for the European Union.After the Second World War and the growth of electronics, specialized EMC standards were created toassure reliable equipment operation in such critical applications as aircraft, military, medical andautomotive. The regulation of RF emissions from consumer products was given a boost from the advent ofthe personal computer. Numerous complaints of interference to radio and TV reception from personalcomputers led in the United States to the adoption of Subpart J to the FCC’s Part 15 rules in 1979. Theregulation of RF emissions from personal computers has spread throughout the world, with a fewexamples shown below: • FCC Part 15, subpart J 1979 • IEC CISPR 22 1985 • VCCI in Japan 1985 • Canada Radio Act 1988 • Australian EMC Framework 1996 • Taiwan ITE EMI 1997 • Korea ITE EMC 1998 • Singapore EMI for telecom 2000 In 1989 the FCC consolidated its Part 15 rules into Subparts A, B and C. But thanks to the unstoppableflow of new communication technologies, the Part 15 rules have grown back to include Subpart G, with anew Subpart H already proposed. Today, RF emissions are regulated in most developed countries to protectbroadcast services (radio, TV) and sensitive services (radio-navigation, satellite communications, radio-astronomy).The first widespread application of RF immunity requirements was introduced with the European Union’sEMC Directive published in 1989 and originally to take effect in 1992. However, the lack of suitable EMCstandards – and the lagging preparedness of manufacturers – led to a delay until 1996. The original EMCDirective 89/336/EEC is replaced by a new Directive 2004/108/EC, with a transition period 20 July 2007 –20 July 2009. EMC for radio equipment in the EU is mandated by the R&TTE (Radio andTelecommunications Terminal Equipment) Directive 1999/5/EC.Worldwide EMC regulations, including limits and measurement procedures, are changing constantly andrepresent a moving target for product development.www.intertek-etlsemko.com 2
RF emissions limits have been established for the threshold sensitivities of typical “victim” receivers such asradio and TV, and on the “protection distances” that may be available to increase the spacing between RFemitter and victim. The common protection distances are 10 meters for residential environments and 30meters for non-residential. Most emissions standards allow scaling to other measurement distances such as3 meters.The equipment designer needs to know that the EMC environmentinterpretation of EMC environments can differ USA EU+between jurisdictions. In the USA, the FCC hasdefined the Part 15 Class A environment asanything except residential or consumer. EU non-residential industrial Class Ageneric EMC regulations define Class B morebroadly. It may include commercial and light residential,industrial environments. For ITE, however, it is Class B residential commercial,acceptable to allow Class A emissions in light industrialcommercial and light industrial locations. Emissions increase Immunity disturbancesImmunity environments are generally defined by the electromagnetic “threats” or disturbances that mayexist there. For example, the generic industrial immunity standard IEC 61000-6-2 defines an industrialenvironment both from the nature of the AC connection: - to a power network supplied from a high or medium voltage transformer dedicated to the supply of an installation feeding manufacturing or similar plantwhich could conduct disturbances from the equipment to other “victims,” and to the surrounding“threats” as: - industrial, scientific and medical (ISM) apparatus - heavy inductive or capacitive loads are frequently switched - currents and associated magnetic fields are highThe equipment designer or design team needs to assure that their EMC objectives take into account anyregulatory differences among jurisdictions regarding the definitions of the EMC environment.Consider EMC early in the design processThere are many opportunities during the productdevelopment process between concept and marketentry where EMC criteria should be established, The design processvalidated, tested and perhaps modified. The Design concept Target Systemfeedback implied in Figure 3 does not necessarily rulesmean a mid-course correction (although one mightbe justified), but rather an opportunity to captureEMC information for use in future projects as ameans of process improvement. ISO 9000-registered manufacturers should consider including Regulatory Functional Initial release evaluation designwww.intertek-etlsemko.com 3
these review steps in their equipment development program.Some specific EMC considerations are suggested below for each of the design steps shown in Figure 3:Target Specifications The details (include functional and regulatory— EMC) Are all the jurisdications specified? Have the requirements changed? Is the environment correct?System Architecture The structure and details—EMC How many layers in PCBs? Are reactive circuits located away from I/O ports? Are I/O ports isolated/shielded? Are IC families appropriate for speeds needed? Will housing provide shielding?Design Rules The circuit and layout constraints—EMC Are RF signal traces short and/or embedded? Are bypass caps located and sized optimally? Are ground planes low-impedance, and earth bypass provided? Have sensitive designs been modeled?Regulatory Evaluation Is it legal? If not modify—EMC Were places provided for optional filtering/bypassing? Are ferrites cost-effective? Can spring fingers be added to the enclosure? Will a shielded cable help? Board re-spin? Design for complianceNumerous books provide a thorough treatment of EMC design. In a limited space we can only mention afew key considerations for each of the major categories of: - Components - Logic families - PCB layout and I/O - Cables - Enclosure and shielding - Software and firmware Componentswww.intertek-etlsemko.com 4
Smaller, leadless components are contributing to the increased EMC testing success rate in two ways: (1)the absence of leads reduces the connection inductances, allowing more effective bypassing and lowerground bounce, and (2) the smaller components permit smaller PC boards, reducing trace lengths that canradiate or absorb RF energy. The effect of lead inductance is illustrated in bypass impedance Figure 4 for a leaded bypass capacitor. At low frequencies the capacitive impedance decreases as frequency increases, allowing for 10 good bypass characteristics. Above a resonant point determined by the capacitor’s nominal value and its internal and external lead impedance, ohms inductances, impedance increases with 1 frequency – reducing the capacitor’s effectiveness at the higher frequencies. Leadless bypass capacitors are more effective at high frequencies owing to their lower connection inductances. 0.1 0.01 0.1 1 10 The same argument can be applied to the frequency, GHz parallel power and ground planes in a PC board. These constitute effective bypass capacitors with low inductances.www.intertek-etlsemko.com 5
Logic familiesSelection of logic families for a particular design should use the slowest speed consistent with targetfunctionality. Excessive speed and/or high loads can cause EMC problems, because: • Emissions increase with power consumption • Emissions increase with slew rate/clock speed • Emissions increase with ground bounce • Emissions increase with output loadingDesigners confronted with the need to pass high-speed signals over long distances might wish to considerusing LVDS (Low-voltage differential signaling) logic. LVDS is often used to communicate video data fromthe base of a laptop computer to its flat-screen display. The key benefits of LVDS include a low voltageexcursion and differential drive. PCB layout and I/OKey decisions faced by the designer include number of planes and locations of components. Planes can beused to good advantage for shielding (of internal traces) or bypassing (using the capacitance describedabove). There are tradeoffs because effective bypassing requires the planes to be as close together aspossible, but for shielding they have traces between them. Where unshielded cables exit the PCB, anydigital logic planes should be kept away because the planes carry noise.Traces should be kept as short as possible, and their high frequency impedance is minimized when theratio of length to width is no greater than 3:1. Short straight current elements radiate fields that are: - Proportional to the current they carry - Proportional to their (electrical) length - Increasing with frequencySimilarly, small current loops radiate fields that are: - Proportional to the current - Proportional to the square of the loop radius -- and the square of frequencyLocate I/O drivers as far as possible away from sources of high frequency (clocks) and near the ports theyserve. Otherwise, the high frequency energy will couple to the cables on the I/O ports and the cables willradiate above the applicable limits. CablesConductors exiting the enclosure can perform as effective antennas, radiating at frequencies that aresourced within the enclosure. If the conductors are a pair of wires driven differentially, the opposite andequal signal components on each will tend to cancel one another and any radiated emissions will beminimized. If the signals on each connector are not equal in amplitude and opposite in phase – as with asingle-ended drive – some energy will be radiated and may cause regulatory limit failure.Robust cable shielding can be an effective method of suppressing the emissions from a conductor carryinga single-ended signa. However, the outer shield onsuch shielded cables should be returned via theconnector to an enclosure ground and not a signal ground. The signal ground is generally polluted by noisethat, if connected to the cable shield, could cause the cable shield to radiate above regulatory emissionlimits.www.intertek-etlsemko.com 6
Enclosure and shielding The equipment enclosure can provide shielding aperture shielding effectiveness to reduce RF emissions or improve immunity, 70 only if the enclosure is conductive (metal or plastic) and preserves the continuity of a shielding effectiveness, dB 60 conductive path around the electronic circuitry 50 inside. Any seams or holes in the enclosure 40 10 cm must be sufficiently small to attenuate 30 1 cm electromagnetic disturbances that could enter or exit. Small openings (see Figure 5) can be 20 tolerated, depending on the frequencies of 10 concern. In this chart the dimensions of 1 cm 0 and 10 cm represent the diameter of a circular 0.01 0.1 1 10 opening, the diagonal of a rectangular opening, frequency, GHz or the length of a thin slit or seam. Non- conductive enclosures provide good protectionfrom electrostatic discharge (ESD) but afford no shielding. Software and firmwareNot all of the “heavy lifting” for EMC compliance needs to be accomplished with hardware. Many of themost common immunity disturbances allow the equipment being tested to temporarily degradeperformance during the test, but recover automatically. This functionality can be provided by goodsoftware/firmware design at no hardware cost. These are prudent features in any case, not just for EMCcompliance: - checkpoint routines and watchdog timers. - checksums, error detection/correction codes. - ‘sanity checks” of measured values. - poll status of ports, sensors, actuators. - read/write to digital ports to validate. Pre-compliance testingIn cases where the product development uses modules or subassemblies that have not been previouslyevaluated for EMC, or where marginal EMC performance of the product is suspected, it is prudent toperform some pre-compliance EMC testing. This can only provide approximate results but could revealproblems at an early stage when the corrections can be made quickly and cost-effectively.If the developed product has been tested on an accredited EMC site and failed (or even passed), theaccredited test results can be used to correlate with results on a pre-compliance site to decrease theuncertainty of the pre-compliance results. Pre-compliance RF emissions sitesIt is possible to set up a simple 1m emissions site in an office or factory. By bringing the measurementantenna (which can be rented for the purpose) closer than 3m to the equipment being tested, interferencefrom ambient emissions is minimized. At frequencies above about 100 MHz reflections from any groundwww.intertek-etlsemko.com 7
plane are not relevant in this configuration, so the customary office or factory floor is acceptable. Theantenna is kept at a fixed height of 1m. This site is not well-suited to large equipment, with dimensionsnear or larger than 1m. See Figure 6. If ambient radiated emissions are very high, they can be Pre-compliance EMI site excluded from the 1m pre-compliance site by constructing a screened room around it using a wooden frame and metal 1m mesh. Radiated reflections will be introduced, so any measurements made in the screened room are subject to EUT analyzer additional uncertainties. The screened room can also be used for conducted emission measurements using a LISN (Line Impedance Stabilization Network) or AMN (Artificial Mains floor - not a ground plane Network). Pre-compliance tools – emissionsWith a suitable pre-compliance site available, you can perform simple diagnostic tasks to isolate, identifyand mitigate sources of RF emissions. Take a set of baseline measurements across the frequency range ofinterest, using a suitable EMI receiver or spectrum analyzer (which can be rented for the purpose). Then,perform a succession of operations in turn and observe the results on the screen of the measuringinstrument: - Wiggle I/O or AC cables to correlate with emissions. - Remove I/O cables one by one to determine effect on emissions. - Shield AC cable to chassis with tin foil. - Selectively add ferrites, line filters or bypassing to localize reactive cable. - Use EMI probes (below)If an emission of interest has been identified, its source on the equipment or circuit board can likely beidentified by using either a proximity probe or a contact probe; see Figures below.The proximity probe is moved around the enclosure or circuit board until an emission is located at the samefrequency as the one found using the antenna. By locating the highest emission with the proximity probe,you have likely – but not definitely – located the source of the emission. The contact probe allows you totouch individual PC traces or component leads in searching for the frequency of interest.www.intertek-etlsemko.com 8