Emc safety


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Emc safety

  1. 1. Insider’s Guide to Faster Safety & EMC Testing Intertek Testing Services 70 Codman Hill Road, Boxborough, MA www.intertek-etlsemko.com
  2. 2. 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.
  3. 3. 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.
  4. 4. 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
  5. 5. 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.
  6. 6. 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.
  7. 7. 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
  8. 8. 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
  9. 9. 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
  10. 10. 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
  11. 11. 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.
  12. 12. 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.
  13. 13. 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.
  14. 14. Insider’s Guide to Faster Safety & EMC TestingAbout the AuthorsRoland Gubisch is the Chief Engineer, EMC and Telecom, Intertek Testing Services. Inthis capacity he is responsible for the technical activities in EMC andtelecommunications testing of Intertek laboratories in the US and Canada. He has beenwith Intertek for 17 years. He is also the Certification Body Manager at Intertek for FCCand Industry Canada radio certification activities.His industry activities include the IEEE Working Group for Power Line CommunicationsEMC standards, membership in the Administrative Council for Terminal Attachments(ACTA), and TIA liaison groups with the FCC for wireless communications. He holdsdomestic and international patents in the fields of optical and chemical instrumentation,and network test apparatus. He is a member of the IEEE, and IEEE Communicationsand EMC Societies.Jim Pierce is the Chief Electrical Engineer for Intertek Testing Services. He began hiscareer with UL over 30 years ago as an Engineering Technician and moved up in theorganization to managing 40 engineering staff. He joined Intertek in 1990 and heldvarious engineering management positions over the years.His responsibilities include: preparing and conducting training programs for Intertek’stechnical staff and monthly worldwide training webinars and annual requalification ofReviewers Webinar sessions.Mr. Pierce is a member of the National Fire Protection Association (NFPA) and iscurrently serving on National Electrical Code (NFPA 70) Panel #18 and is also amember of the NFPA 79 Technical Committee (Industrial Machines). He also serves onmany ANSI, NEMA, NFPA and UL Standards Maintenance Review Boards. In addition,he has been an Inspector member of the International Association of ElectricalInspectors (IAEI) and has served on their monthly Code Panel Forums, for over 17 years.Natasha Moore is a technical author and editor specializing in electrical safety andcertification information. Based at Intertek UK, she was the contributing editor of ASTABEAB’s Update magazine and recently wrote the Intertek whitepaper “The EngineersGuide to Solving World Problems: 5 Strategies for Efficient Global Market Access.” For more information on specific testing and certification information, please contact Intertek at 1-800-WORLDLAB, email icenter@intertek.com, or visit our website at www.intertek-etlsemko.com.This publication is copyright © Intertek and may not be reproduced or transmitted in any form in whole or in part without the priorwritten permission of Intertek. While due care has been taken during the preparation of this document, Intertek cannot be heldresponsible for the accuracy of the information herein or for any consequence arising from it. Clients are encouraged to seekIntertek’s current advice on their specific needs before acting upon any of the content.