emc testing brochure

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 protected] 800-WORLDLAB www.intertek-etlsemko.com

www.intertek-etlsemko.com 1

Engineer’s Guide to Global EMC Requirements

Table of Contents

Introduction……………………….……………………………………….2

Background………………………………………………………………..2

EMC as a mandatory compliance requirement………………………....3

Regulatory compliance procedures………………………..……………..4

Regulatory compliance frameworks……………………………………...4

Authority 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………………..………………………………………..16



Introduction

Engineers everywhere would like to test their products only once for electromagnetic compatibility (EMC), using a single set of standards and placing a single mark on the products to allow them to be sold around the world. Unfortunately, that aspiration will not become reality any time soon. If anything, it is becoming even more elusive as companies pursue 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 region retains 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 around the world. Background EMC issues have been around since the early days of telegraphy and radio. Interference from solar activity caused “phantom telegraph operators” – telegraph output with no telegraph input – on long parallel transmission wires. The cure for this condition was occasional twists in the wires, which led directly to today’s high-speed twisted-pair LAN wiring. With the increasing popularity of broadcasting, and then with the use of electronic equipment in commercial and military applications, rules to prevent radio interference and equipment malfunctions became necessary. The result has been a succession of EMC standards 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 interference



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 similar emissions 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 equipment

EMC as a mandatory compliance requirement

The 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 met before the products can be marketed in those countries. The overall scope of your efforts will be determined by the number of countries in which you wish to sell your products, of course. However, to keep this paper manageable – while providing a flavor of the issues to be encountered - we will limit the list to the following regions:

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 EMC testing for the US and EU. Is that enough to allow you to place products everywhere in the



world? Unfortunately, it is not. Many countries that require EMC compliance also impose additional hurdles to market entry in terms of deviations to international standards, in-country testing or country presence. Fortunately, there are also simplifying arrangements and agreements that can leverage your EMC testing to cover larger geographical or market areas. They are found under the broad umbrella term MRA (Mutual Recognition Agreements or Arrangements). Regulatory compliance procedures

Countries or regions that regulate product EMC will typically employ one or more of three procedures to determine compliance with national or regional requirements. The particular procedure 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 the applicable standards, compliance procedures and contact information for each target country or region. Fortunately, there are simplifying frameworks to lighten the burden .

Regulatory compliance frameworks

Mutual Recognition Agreements or Arrangements (MRAs) are multilateral agreements among countries or regions which facilitate market access for signatory members. MRAs can cover the mutual recognition of product testing, certification or both. However, the existence of an MRA does not imply harmonization of the standards among the participants. For example, the interpretation of appropriate Class A or Class B emission limits in a commercial environment can differ between the US and the EU, as reflected in their respective standards and illustrated below:



Some 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 US covering EMC, radio, telecom and several other product sectors. It has become a model for subsequent MRAs. Other MRAs in operation or pending that cover EMC and telecom include:

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 CITEL



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 include Australia, 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 be accepted in another region or country − facilitating market access without additional testing. Regarding EMC, this is especially important when the destination country requires certification as a regulatory requirement. Authority Having Jurisdiction over EMC

As you investigate each country to determine which agency has the EMC authority for your products, you should also be able to determine what those requirements are. Around the world, RF emissions or EMI is regarded as a potential threat to broadcast reception and to sensitive services such as radio navigation and radio astronomy. Therefore the spectrum or radio regulator in each country or region is usually charged with the widest responsibility for controlling EMI. Immunity, on the other hand, may be reserved as a performance issue for critical applications such as medical or military – and the regulator may differ in each case. The combination of EMI and immunity as EMC may also be used as a means to establish uniform trade rules across a region, as it is in the EU. The following is a brief overview of what you need to consider as you investigate the requirements for each country. We will use the US as a detailed example. AMERICAS US

• 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 unintentional



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 in the US. The table below summarizes some of this EMC information in a convenient format for comparison with other jurisdictions. Jurisdiction United States - EMC



Product type ITE Radio Appliance Medical

Authority FCC FCC FCC exempt FDA/CDRH

Approval Procedures

EMI only: Verification

DoC: accredited Cert: accredited

Certification N/A Certification

In-country testing required?

No No N/A No

MRA with US?

N/A N/A N/A N/A

Marks For DoC only:

FCC logo None N/A N/A

Canada

• 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 - EMC


Authority Industry Canada Industry Canada IC exempt Health Canada

Approval Procedures

EMI only: Verification

Certification N/A Licensing


No No N/A No

MRA with Yes, Phase I Yes, Phases I & II N/A No



US?

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 - EMC


Authority INMETRO ANATEL INMETRO ANVISA

Approval Procedures

N/A Certification and Homologation

N/A Registration


N/A Yes N/A No

MRA with US?

Pending Pending N/A N/A

Marks no no N/A N/A

EUROPE EU With 27 member states, the population and economy of the EU exceeds that of the US. The EU has simplified the process of access considerably by identifying the “essential requirements” for almost everything that is placed on the market in the EU. The authorities having jurisdiction vary by product type, and each country has a Competent Authority for each product type or directive. For example, the Competent Authority for EMC in the UK is the Department of Trade and Industry (DTI). The specific “essential requirements” for your products will be listed in the directives that apply to your product. In most cases, the



directives will be “New Approach” directives for which CE marking signifies compliance and the applicable standards have been published in the Official Journal of the European Union. A good place to start for guidance on directives and standards is http://www.newapproach.org. The CE marking indicates that the equipment bearing the marking 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 – EMC


Authority EMC Competent Authority

Spectrum Competent Authority

EMC Competent Authority

Medical Competent Authority

Approval Procedures

Verification. Notified Body

opinion may be obtained

Verification. Notified Body

opinion may be rendered.

Verification

Verification, DoC, Type

Examination, Notified Body

approval

In-country testing

No No No No



required?

MRA with US?

Yes, Phases I & II Yes, Phases I & II Yes, Phases I & II Yes, Phases I & II

Marks CE

CE, possibly Notified Body number, alert

mark

CE CE and Notified Body number

where applicable

Russia

• 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 manufacturer's 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:



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 - EMC


Authority GOST Glavgossvyaznadzor GOST Roszdravnadzor

Approval Procedures

Certification Certification, licensing

Verification Registration


No Yes No Yes

MRA with US?

No No No No

Marks GOST-R No GOST-R No FAR EAST Japan

• 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.



• 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 - EMC


Authority MIC METI MHLW

Approval Procedures

Registration Certification, SDoC

Certification, verification

Licensing


No No No No

MRA with US?

Yes, 2007 Yes, 2007 No No

Marks

Class B: VCCI mark

Class A: Kanjii text

Technical Conformity

Mark PSE or none None

China (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 product



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 - EMC


Authority CNCA CNCA CNCA SFDA, MOH

Approval Procedures

Certification; see:

CNCA-01C-020

Certification; see:

CNCA-07C-031 for examples

Certification; see:

CNCA-01C-016

Certification; seeCNCA-08C-032

to 043 for examples; also Registration


Yes Yes Yes Yes

MRA with US?

No No No No

Marks CCC CCC CCC CCC Chinese 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 emissions



(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 of Economic

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 - EMC


Authority BSMI NCC BSMI DOH

Approval Procedures

DoC and certification

Certification Certification, registration

Licensing


No No No No

MRA with US?

Yes, Phase I Yes, Phase I No No

Marks Commodity inspection mark

NCC Commodity inspection mark

No

Conclusion This paper has provided a quick overview of what is required to ensure that EMC requirements 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 own list of country requirements. As you expand your list, you will be able to weigh the challenge of meeting compliance criteria and procedures for several nations simultaneously. Compliance has to be taken very seriously; the penalties for not complying vary from simple quarantine of your products at customs to severe measures such as monetary fines and even imprisonment.



If global EMC compliance issues are a recent challenge for your company, or if your current compliance 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 322 laboratories in 110 countries around the world, 20 of them in the US alone, In addition to MRA arrangements, we have special agreements with agencies and labs in many other countries including Israel, Brazil, Russia, and Belarus. By working with a partner lab, it is easier to assemble a product- or technology-specific test and certification plan that maximizes your testing dollar and gives you the additional resources needed to seek global compliance. You have the security of knowing that the plan 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 [email protected]. Intertek gets you the answers you need—within 24 hours. We look forward to helping you.

Intertek Testing Services 70 Codman Hill Road, Boxborough, MA

www.intertek-etlsemko.com

Insider’s Guide to Faster Safety & EMC Testing

Introduction

Bringing a new product to market is a complex and involved process that requires the talent and expertise of a wide range of personnel within an organization; business strategists, product designers and engineers, production teams and line staff to name a few. Amidst the flurry of development activity within these teams, Safety and EMC product compliance issues may seem to be a low priority – at very least until a prototype is built. Indeed how can you test something for compliance when it doesn’t actually exist? By postponing compliance considerations until later in the development cycle, it can cause delays in launching a product to market. Testing can reveal non-conformities that require a product redesign or modification then retest – lengthening the compliance process significantly. Indeed it is common that modifications made to a product for EMC compliance can effect safety compliance. For example, having to add extra insulation into a product can reduce the current creepage and clearance distances required for safety purposes, potentially making it unsafe. Similarly, changing bypass capacitors to comply with safety leakage current requirements can throw off EMC compliance. The product then has to be modified to fix this problem and then retested for safety. With such a potentially complex situation, it seems obvious that product safety and EMC compliance should be considered from the earliest concept stages of development (and in an integrated way) to keep launch disruption to a minimum. Product modification and retest delays can have a critical impact on your business, potentially costing you thousands in lost revenue (missing out on Holiday sales for example) as well as damage to your brand. Your competitors could get their rival products to market first, making them - in a consumers mind at least - a “leader” and everyone else that comes after a “follower”. In this document, we will explore some simple, practical strategies that ensure these compliance considerations can be addressed early, and enable the compliance process itself to be optimized to help reduce time to market, costs, chances of delay and the likelihood of having to make frustrating modifications and retests to your product.

Knowledge is Power

It 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 done is market research. Is the product needed/wanted in the marketplace? What are the competitive products, and what are their weaknesses? What features would make the new product better than anything else available? What would its life be? Would it need to be repairable/upgradeable? Does it have to be functional or aesthetic or both? How much should it cost? And most importantly, to whom is this 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 itself as you can use the existing knowledge of your engineers to identify the probable Safety and EMC test plan and likely costs – based on previous projects. For example, in the US, domestic products must be tested for EMC emissions, not immunity. In Europe, domestic products must be tested for both. If your product is going to Europe, your test plan for compliance in this region is therefore likely to take a little longer, cost a little more and will probably require more samples and spares to be provided to the test house. These factors can then be built into your 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 Deviations Knowing the safety and EMC regulations for a new product in the target market is essential for the product development team. This enables them to obtain appropriate Standards for those markets (indeed they can select Standards that give them maximum geographical coverage) and design the product with the safety and EMC requirements of these Standards in mind. Standards & Jurisdiction US - FCC/ FDA US/EU - FCC, IEC, CENELEC Asia Pacific - FCC or IEC with deviations Product Jurisdiction Standard ITE USA FCC Part 15, 60950-1 ITE EU, Asia CISPR 22/EN 55022, CISPR 24/EN 55024 Medical USA, International IEC 60601-1-2 Test/Measurement 61010-1 Audio/Visual 60065 Household Appliances 60335-1 Electrical Tools 60745-1 ISM USA FCC Part 18 ISM EU, Asia EN 55011 +… Lab USA Exempt Lab EU EN61326-x Radio USA FCC Part 15, 22, 24, 25, 27, 74, 90, 95 Radio EU ETSI EN, EN 301 489 -x

Insider’s Guide to Faster

Safety & EMC Testing

Purposefully designing a product for safety and EMC conformity seems a cautious and conservative approach to product design that restricts creativity and innovation, but it is likely to reduce your chances of product failure at the testing stage. 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 in

those sections relating to specific tests to be conducted, can be interpreted in a number of ways. Calling upon the expertise of a testing and certification partner to interpret the fine detail of a Standard can help designers and engineers overcome the hazards of ambiguity and potential product non-conformity. If the issue has particular subtleties, your test partner can even approach the Standards Developing Organisation (SDO) directly for a definitive explanation. The second issue with in-house Standards libraries, is the need to maintain the latest version of the Standard. When potentially dozens of Standards need to be maintained, it is possible that an expiring document may be overlooked. Here auditors and quality managers play their part in keeping the available documents up to date – but again your testing and certification body can provide you with the latest (and upcoming) Standards updates and information on local safety and or EMC 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 a non-compliant product design, or, how expensive is it to miss a product launch date in the market place? Purchase of the standard is a good investment and is quite inexpensive when compared to the cost of re-submittal to the test lab.



Understanding Dates of Withdrawal (DOW) and Standard Version terminology Ensuring that you’re using the appropriate standard is an obvious thing, but understanding the validity of dates within those standards is critical to using the right one! It would be incredibly frustrating to commission product tests against a Standard in your library and then find that it is soon to expire and that any testing and certification will need to be revisited. The new version of the Standard my not require any additional tests to be completed – it could be a something as simple as a new labelling requirement, but it could require product modifications and a re-test. Understanding how the dating information in Standards works could save you time and expense in having to revisit your test program soon after completion because the Standard that was tested against is no longer the newest version. Outlined below are some brief explanations of critical Standard dates and terminology for standards in the EU: Approved Draft The Approved Draft Date is usually found in the Foreword at the front of the Standard. This date is essentially when the Standard text was “Approved” by CENELEC, prior to publication by the National Standards Bodies. DOP - Date of Publication The DOP or Date of Publication is the date by which the Standard must be published by all countries’ National Standards Bodies. The DOP is usually 6-12 months after the document has been “Approved” by (for example) CENELEC and once the document is published, it becomes the current version of the Standard. Amendment Dates As you would expect, Amendments to Standards (also found in the foreword and designated with the letter A and numbered in sequence e.g. A1, A2 etc) also have an Approved Draft Date and a DOP, but in European Standards, you will also find a Date of Withdrawal (DOW). This DOW indicates the date when the Standard it is associated with can no longer be used on its own - i.e. without the new Amendment. DOWs are also found on fully re-issued Standards. It doesn’t indicate that the Standard as a whole will cease to be current on that date.



Amendment 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 if

you 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 two different amendments to that Standard; one for International use, one for European. BS, EN & IEC The name of a Standard will be designated with a BS, EN or an IEC. A BS designation indicates a British Standard, an EN designation indicates that it is a European Standard and an “IEC” designation indicates a worldwide Standard. Part 1s and Part 2s Many Standards will be divided into part 1s and part 2s. Part one usually refers to a generic category of products - for example “Household and similar electrical Appliances” and gives details of general requirements for them and part two refers 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 Standard that is still current. For example if I test a product to a particular Standard and then an amendment is published for it, my product will not comply with the most current (now amended) version of the Standard once the Date of Withdrawal on that Amendment is passed. Similarly, if you have a Certification for a product that doesn’t expire for several years - but the Standard that was used to get that Certification gets Amended before your certification runs out, you must contact your Certification Body to enable them to determine what you need to do to comply with the latest version



of the Standard. Sometimes you may need to do additional testing - sometimes the conformity is purely a documentary exercise but you must ensure that your product meets the most current version of the Standard. The Devil is in the Details: Designing for Compliance Continue to use the knowledge and expertise of your product designers and engineers to “design for compliance”, but also use the available product Standards as design reference tools and even look at existing best of breed products to see how they have overcome certain design challenges. By establishing safety and EMC compliance as a fundamental design goal, along with functionality, ease of use, aesthetics etc at the start of the design process, compliance issues can be tackled earlier in the design cycle. Compliance will be seen as a production imperative not a last minute addition to the project. This will reduce chances of product failure 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



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 Components Where possible use listed or certified components in critical systems in the product. e.g., controls, transformers, components in the 120 or 240 primary circuit, etc (and know their ratings and conditions of use) as these will contribute to the overall compliance of your product. Also with some specific products – like UK plugs for example, having certified sub-systems like pre-approved moulded pin inserts means that some of your testing has already been done and you could save money on your overall test program.

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 of

components (and even materials) seems a bargain that is too good to be true, it probably is. A Note on Modifying Established Products If you are redesigning or modifying an existing product, even if you are simply swapping one component for another from a different supplier, don’t forget to tell your testing and Certification/Approval partner, so they can determine if any additional testing is required. Swapping one component for another may have implications that weren’t anticipated when the substitution was made and if you don’t notify your partner; it may invalidate your certification. Very often



substitutions 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 auditing purposes. Putting Pen to Paper Documenting the design and production process is invaluable for the compliance process. Quality Management tools and Project Management systems provide a useful 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-conformity during the testing process, but it will also help them to keep track of components and schematics for easy reference – particularly if they are creating a suite of products. The testing and certification team at your partner laboratory will require access to the component and materials lists as well as circuit diagrams and drawings in order to be able to test and assess the product. Surprisingly, a great many testing and approval projects get delayed, not because of the modification of product or because a failure of tests, but because the test lab hasn’t had all of the paperwork they need to move a project forward. It seems bureaucratic, but as test houses and certifying bodies are regularly audited to ensure the work they do is to a consistent and of high standard, they need to have all of the relevant documentation necessary to conduct the work. Sometimes the most simple of required “paperwork” (user manual, installation instructions, product markings, etc.) is not provided. If a manufacturer can have all of the relevant documentation 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 numbers and email addresses for the team at the test lab, and some calendar notes to check in regularly with them to check on the project progress. Some



manufacturers don’t do this as they want no part of the compliance process, but many others have found an active dialogue with the test house and an understanding of and proactive involvement in the process can help reduce the time it takes and reduces the number of potential issues that could arise. Design Review Many manufacturers have found it beneficial to have a design review conducted by their test or certification partner. This highlights any design issues early and can be conducted using the circuit diagrams, component lists, design drawings – and if it is available, a prototype. Initial discussions with the certification partner can even begin with an artists rendering or cardboard mock-up. If necessary the product 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 a source 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 conducting

some preliminary testing yourself, can help give you some initial feedback on where your product might fail, enabling you to make appropriate modifications before a product reaches the formal testing stage.



What can a man with a radio do? The most basic of all EMC tests – that you can conduct yourself without specialist equipment or test chambers - is the radio test. Switch on your radio and hold it near your live appliance and see if the reception becomes distorted. If it does, it’s likely that your product needs better emissions mitigation. Other basic bench tests can usually be conducted at site with some help from your test laboratory team. They can give you direction on equipment you will need, guidance on specific tests and even observe some testing so it can be included in the formal compliance assessment. Keep it in the Family When you are submitting products to the laboratory for testing, group them into a family of products, and submit as many similar items as is feasible at the same time. This will help to reduce the cost and time required for the compliance process 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 the

development of where issues typically lay. This will help manufacturers to prepare their product for test and reduce the likelihood of failure.



Conclusion In a global market where the ability to innovate and respond to market needs with new and vibrant products is the mark of world leading brands, time to market is a key factor in determining both the success of a particular product and ultimately the ongoing commercial success of a company. As each trading area in the world has 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 manufacturer can:

• 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 with these simple, common sense efforts, they can at least be reduced. Designing for compliance is an unromantic notion, but a common sense one. You can optimize the testing process with proactive involvement, but a well designed product that meets all of the criteria required of it, will be the most influential factor in getting through the compliance process, fast.



About the Authors Roland Gubisch is the Chief Engineer, EMC and Telecom, Intertek Testing Services. In this capacity he is responsible for the technical activities in EMC and telecommunications testing of Intertek laboratories in the US and Canada. He has been with Intertek for 17 years. He is also the Certification Body Manager at Intertek for FCC and Industry Canada radio certification activities.

His industry activities include the IEEE Working Group for Power Line Communications EMC standards, membership in the Administrative Council for Terminal Attachments (ACTA), and TIA liaison groups with the FCC for wireless communications. He holds domestic and international patents in the fields of optical and chemical instrumentation, and network test apparatus. He is a member of the IEEE, and IEEE Communications and EMC Societies. Jim Pierce is the Chief Electrical Engineer for Intertek Testing Services. He began his career with UL over 30 years ago as an Engineering Technician and moved up in the organization to managing 40 engineering staff. He joined Intertek in 1990 and held various engineering management positions over the years. His responsibilities include: preparing and conducting training programs for Intertek’s technical staff and monthly worldwide training webinars and annual requalification of Reviewers Webinar sessions. Mr. Pierce is a member of the National Fire Protection Association (NFPA) and is currently serving on National Electrical Code (NFPA 70) Panel #18 and is also a member of the NFPA 79 Technical Committee (Industrial Machines). He also serves on many ANSI, NEMA, NFPA and UL Standards Maintenance Review Boards. In addition, he has been an Inspector member of the International Association of Electrical Inspectors (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 and certification information. Based at Intertek UK, she was the contributing editor of ASTA BEAB’s Update magazine and recently wrote the Intertek whitepaper “The Engineers Guide 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 [email protected], 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 prior written permission of Intertek. While due care has been taken during the preparation of this document, Intertek cannot be held responsible for the accuracy of the information herein or for any consequence arising from it. Clients are encouraged to seek Intertek’s current advice on their specific needs before acting upon any of the content.

Why 50% of Products Fail 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 protected] Web: www.intertek-etlsemko.com


60 50 40 30 20 10

ITE

Medical

1st 2nd 3rd trial

Learning curve – plus knowing exactly what

Failu

re

Summary A large percentage of electronic products fail to meet their target EMC requirements the first time they are tested. In this article we look at some of the possible reasons for that failure rate, and what designers and manufacturers 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 products have decreased gradually. Improved success may be the result of growing awareness of EMC design considerations, use of EMC software, reduced circuit dimensions or all of these factors. Nevertheless, we continue to see EMC test failure rates around 50%. Looking more deeply into the numbers, we note that, for example, medical products are slightly more successful (~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 standard IEC 60601-1-2 over the ITE standards CISPR 22 and 24, but two factors may work in favor of medical products. 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 EMC considerations apply to both medical and ITE.

Fortunately, the EMC learning curve for products that fail initially is quite steep. Presumably taking advantage of both the EMC education provided by the first go-around, as well as the pinpointing of EMC problems, manufacturers reduce the failure rate on the EMC re-testing to the level of 5% - 7%. Very challenging products may require a third round of EMC testing, for which we observe a failure rate reduced to 1% - 2%.

Based on our experiences with a wide variety of equipment suppliers, we can summarize the leading observed 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 product

These topics are discussed briefly in the context of a product design and development program intended to maximize the likelihood of success in the initial EMC testing.


EMC regulations Although RF interference considerations have existed since the advent of radio, commercial EMC regulations (both emissions and immunity) are relatively recent – and continuously changing. Equipment designers and regulatory compliance engineers have to work hard to identify and keep abreast of the EMC regulations 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 interference issues. Parallel laws were enacted around the world, with Germany providing early leadership in laws and standards that provided a model for the European Union. After the Second World War and the growth of electronics, specialized EMC standards were created to assure reliable equipment operation in such critical applications as aircraft, military, medical and automotive. The regulation of RF emissions from consumer products was given a boost from the advent of the personal computer. Numerous complaints of interference to radio and TV reception from personal computers led in the United States to the adoption of Subpart J to the FCC’s Part 15 rules in 1979. The regulation of RF emissions from personal computers has spread throughout the world, with a few examples 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 unstoppable flow of new communication technologies, the Part 15 rules have grown back to include Subpart G, with a new Subpart H already proposed. Today, RF emissions are regulated in most developed countries to protect broadcast 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’s EMC Directive published in 1989 and originally to take effect in 1992. However, the lack of suitable EMC standards – and the lagging preparedness of manufacturers – led to a delay until 1996. The original EMC Directive 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 and Telecommunications Terminal Equipment) Directive 1999/5/EC. Worldwide EMC regulations, including limits and measurement procedures, are changing constantly and represent a moving target for product development.


RF emissions limits have been established for the threshold sensitivities of typical “victim” receivers such as radio and TV, and on the “protection distances” that may be available to increase the spacing between RF emitter and victim. The common protection distances are 10 meters for residential environments and 30 meters for non-residential. Most emissions standards allow scaling to other measurement distances such as 3 meters. The equipment designer needs to know that the interpretation of EMC environments can differ between jurisdictions. In the USA, the FCC has defined the Part 15 Class A environment as anything except residential or consumer. EU generic EMC regulations define Class B more broadly. It may include commercial and light industrial environments. For ITE, however, it is acceptable to allow Class A emissions in commercial and light industrial locations. Immunity environments are generally defined by the electromagnetic “threats” or disturbances that may exist there. For example, the generic industrial immunity standard IEC 61000-6-2 defines an industrial environment 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 plant

which 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 high

The equipment designer or design team needs to assure that their EMC objectives take into account any regulatory differences among jurisdictions regarding the definitions of the EMC environment. Consider EMC early in the design process There are many opportunities during the product development process between concept and market entry where EMC criteria should be established, validated, tested and perhaps modified. The feedback implied in Figure 3 does not necessarily mean a mid-course correction (although one might be justified), but rather an opportunity to capture EMC information for use in future projects as a means of process improvement. ISO 9000-registered manufacturers should consider including

Class A

Class B

USA EU+

non-residential

residential

industrial

residential, commercial,

light industrial

Emissions increase Immunity disturbances

EMC environment

concept Target

releaseInitial design

Designrules

Functional

System

Regulatory evaluation

The design process


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 compliance

Numerous books provide a thorough treatment of EMC design. In a limited space we can only mention a few key considerations for each of the major categories of:

- Components - Logic families - PCB layout and I/O - Cables - Enclosure and shielding - Software and firmware

Components


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 lower ground bounce, and (2) the smaller components permit smaller PC boards, reducing trace lengths that can radiate or absorb RF energy.

The effect of lead inductance is illustrated in Figure 4 for a leaded bypass capacitor. At low frequencies the capacitive impedance decreases as frequency increases, allowing for good bypass characteristics. Above a resonant point determined by the capacitor’s nominal value and its internal and external lead inductances, impedance increases with 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. The same argument can be applied to the parallel power and ground planes in a PC board. These constitute effective bypass capacitors with low inductances.

bypass impedance

0.1

1

10

0.01 0.1 1 10

frequency, GHz

impe

danc

e, o

hms


Logic families Selection of logic families for a particular design should use the slowest speed consistent with target functionality. 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 loading

Designers confronted with the need to pass high-speed signals over long distances might wish to consider using LVDS (Low-voltage differential signaling) logic. LVDS is often used to communicate video data from the base of a laptop computer to its flat-screen display. The key benefits of LVDS include a low voltage excursion and differential drive.

PCB layout and I/O Key decisions faced by the designer include number of planes and locations of components. Planes can be used to good advantage for shielding (of internal traces) or bypassing (using the capacitance described above). There are tradeoffs because effective bypassing requires the planes to be as close together as possible, but for shielding they have traces between them. Where unshielded cables exit the PCB, any digital 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 the ratio 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 frequency

Similarly, small current loops radiate fields that are:

- Proportional to the current - Proportional to the square of the loop radius -- and the square of frequency

Locate I/O drivers as far as possible away from sources of high frequency (clocks) and near the ports they serve. Otherwise, the high frequency energy will couple to the cables on the I/O ports and the cables will radiate above the applicable limits. Cables Conductors exiting the enclosure can perform as effective antennas, radiating at frequencies that are sourced within the enclosure. If the conductors are a pair of wires driven differentially, the opposite and equal signal components on each will tend to cancel one another and any radiated emissions will be minimized. If the signals on each connector are not equal in amplitude and opposite in phase – as with a single-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 carrying a single-ended signa. However, the outer shield onsuch shielded cables should be returned via the connector to an enclosure ground and not a signal ground. The signal ground is generally polluted by noise that, if connected to the cable shield, could cause the cable shield to radiate above regulatory emission limits.


Enclosure and shielding

The equipment enclosure can provide shielding to reduce RF emissions or improve immunity, only if the enclosure is conductive (metal or plastic) and preserves the continuity of a conductive path around the electronic circuitry inside. Any seams or holes in the enclosure must be sufficiently small to attenuate electromagnetic disturbances that could enter or exit. Small openings (see Figure 5) can be tolerated, depending on the frequencies of concern. In this chart the dimensions of 1 cm and 10 cm represent the diameter of a circular opening, the diagonal of a rectangular opening, or the length of a thin slit or seam. Non-conductive enclosures provide good protection

from electrostatic discharge (ESD) but afford no shielding.

Software and firmware Not all of the “heavy lifting” for EMC compliance needs to be accomplished with hardware. Many of the most common immunity disturbances allow the equipment being tested to temporarily degrade performance during the test, but recover automatically. This functionality can be provided by good software/firmware design at no hardware cost. These are prudent features in any case, not just for EMC compliance:

- 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 testing

In cases where the product development uses modules or subassemblies that have not been previously evaluated for EMC, or where marginal EMC performance of the product is suspected, it is prudent to perform some pre-compliance EMC testing. This can only provide approximate results but could reveal problems 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), the accredited test results can be used to correlate with results on a pre-compliance site to decrease the uncertainty of the pre-compliance results.

Pre-compliance RF emissions sites It is possible to set up a simple 1m emissions site in an office or factory. By bringing the measurement antenna (which can be rented for the purpose) closer than 3m to the equipment being tested, interference from ambient emissions is minimized. At frequencies above about 100 MHz reflections from any ground

aperture shielding effectiveness

0

10

20

30

40

50

60

70

0.01 0.1 1 10

frequency, GHz

shie

ldin

g ef

fect

iven

ess,

dB

10 cm

1 cm


plane are not relevant in this configuration, so the customary office or factory floor is acceptable. The antenna is kept at a fixed height of 1m. This site is not well-suited to large equipment, with dimensions near or larger than 1m. See Figure 6.

If ambient radiated emissions are very high, they can be excluded from the 1m pre-compliance site by constructing a screened room around it using a wooden frame and metal mesh. Radiated reflections will be introduced, so any measurements made in the screened room are subject to additional uncertainties. The screened room can also be used for conducted emission measurements using a LISN (Line Impedance Stabilization Network) or AMN (Artificial Mains Network).

Pre-compliance tools – emissions

With a suitable pre-compliance site available, you can perform simple diagnostic tasks to isolate, identify and mitigate sources of RF emissions. Take a set of baseline measurements across the frequency range of interest, 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 measuring instrument:

- 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 be identified 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 same frequency 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 to touch individual PC traces or component leads in searching for the frequency of interest.

floor - not a ground plane

Pre-compliance EMI site

EUT

1 m

analyzer


Pre-compliance tools – immunity

Immunity pre-testing requires you to generate electromagnetic disturbances that simulate the requirements in the applicable immunity or EMC standards. The simplest way to perform ESD pre-compliance testing is to rent an ESD “gun” for the purpose. Be sure to review the ESD standard such as IEC 61000-4-2 in order to follow the test procedures and setup as closely as possible. Use a similar approach to surge testing for a standard such as IEC 61000-4-5, and be sure to comply with safety precautions as the surge voltages can be hazardous. RF radiated immunity testing is normally performed in a shielded chamber to avoid radiating illegal RF signals across the radio spectrum. Unless you have constructed a screened room and determined that it provides sufficient shielding effectiveness to prevent unwanted emissions from inside to outside, you should confine any RF radiated emissions pre-compliance testing to the use of certified and/or licensed radio transmitters approved for use in the USA or in the test location. Some convenient transmitter types and their operating frequency bands (for US operation) are listed below:

– CB radio 27 MHz – Portable phone handset 49 MHz (be sure to check; many now operate in

the 900 MHz, 2.5 and 5 GHz bands) – Garage door opener 300 MHz – Walkie-talkie 460 MHz – Cell phone, analog/TDMA 800 MHz – Cell phone, PCS 1900 MHz – Wireless LAN, Wi-Fi 2450 MHz

If insufficient RF immunity is observed during pre-compliance testing, you can experiment with conductive spring fingers to bridge enclosure discontinuities, filters at low RF frequencies and ferrite beads typically above 50 MHz. Modifications for compliance Prudence dictates that a product which has never before undergone EMC testing be designed with a few extra EMC ”hooks” that can be used in the event of EMC problems during regulatory testing. Such “hooks” can be as simple as PCB locations for extra bypass capacitors and/or ferrite beads, or alternate connections for a larger AC line filter. If the equipment passes the regulatory EMC testing with flying colors, the optional positions remain unpopulated. This precaution can avoid board re-spins and a subsequent delay in time-to-market, or even slipping outside of the marketing “window.”


Conclusion In summary, to increase the EMC success rate the designer should:

• Be sure the regulatory specifications are correct and current • Take into account the impact of equipment architecture on EMC, and ensure that purchased

modules also comply. • Consider EMC design rules, manual and/or automatic • Include places for EMC compliance modifications • Perform pre-compliance testing where possible

ETL SEMKO is a division of Intertek plc (LSE: ITRK), a global leader in testing, inspection and certification services, operating in 322 laboratories and 521 offices in 110 countries throughout the world. Intertek provides access to global markets through its local services, which include product safety testing and certification, EMC testing and performance testing for customers in such industries as wireless technology, security, appliances, HVAC, cables and wiring accessories, industrial machinery, medical devices, telecommunications, lighting, automotive, semiconductor, building products and electronics. For more information, visit www.intertek-etlsemko.com, or call 1-800-WORLDLAB

For more information on EMC, and testing products covered under

Intertek’s scope, or to contact Intertek to begin your review right away,

call 1-800-967-5352, email [email protected], or

visit www.intertek-etlsemko.com.

Written by Roland Gubisch www.intertek.com

1-800-WORLDLAB [email protected]

Effects of EMC on Smart Appliance Designs


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Contents

Introduction ..............................................................................................................1 EMC - Electromagnetic compatibility .........................................................................1

Background .......................................................................................................3 EMC ..................................................................................................................3 Emissions - USA .................................................................................................5 Emissions - Japan ...............................................................................................6 Emissions - Australia...........................................................................................7 Designs for emissions compliance.......................................................................8 Emissions and Susceptibility - EU ........................................................................8 Designs for disturbance power compliance.......................................................11 Harmonic and flicker emissions ........................................................................11 Designs for harmonic and flicker emissions compliance.....................................12 Appliance susceptibility and EN 55014-2 ..........................................................12 Designs for susceptibility/immunity compliance.................................................14 Communications..............................................................................................15 Powerline communications...............................................................................15 Radio ...............................................................................................................16 Designs for communications compliance ..........................................................18 Product safety ..................................................................................................18 Functional safety ..............................................................................................19 Electromagnetic exposure ................................................................................19 EU low-frequency EMF limits: EN 50366 ...........................................................20 Designs for EMF compliance.............................................................................21 RF exposure from radios...................................................................................21 Designs for RF exposure compliance .................................................................23


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Introduction

When we hear the term “appliance” we think of common household devices such as air conditioners, blenders, coffee makers, dishwashers, electric knives, fans, microwave ovens, refrigerators and vacuum cleaners. These examples contain among them motors, switches, thermostats and electrically-actuated valves – all well-known electromechanical technologies, with perhaps some simple solid-state electronics added.

Newer appliance designs are reducing cost, expanding functionality and increasing reliability by adopting programmable electronics such as application specific integrated circuits (ASICs), microprocessors, and intelligent sensors, transmitters and actuators. In addition, such “smart” appliances are adopting powerline and wireless communication techniques to enhance their utility even further – for remote control over a “smart grid,” or for remote recordkeeping, for example.

The migration of appliance technology from electromechanical to programmable electronic and wireless has significant consequences for EMC design and regulatory compliance. Even for simple appliances, the designer may be faced with unfamiliar standards governing user safety and radio interference. For more complex appliances, stringent “functional safety” requirements may affect EMC testing.

This document is intended to help the reader become aware of global EMC issues and design considerations for “smart” appliances. It is not intended as a comprehensive catalog or toolkit. EMC consultants and test laboratories can provide targeted assistance with up-to-date information on regulations and compliance procedures.

EMC - Electromagnetic compatibility

Electromagnetic compatibility is defined as the condition which exists when equipment is performing its designed functions without causing or suffering unacceptable degradation due to electromagnetic interference to or from other equipment. EMC refers to a kind of environmental equilibrium. In this case, the environment is an electromagnetic one - consisting of invisible disturbances which travel through the air or through metal cabinets or wires.


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EMC has two components, illustrated in the diagram below:

1) Electromagnetic emissions, from the appliance itself; emissions from the appliance can interfere with radio and TV broadcasting or sensitive services such as radio navigation or radio astronomy. The term EMI (Electromagnetic Interference) refers to electromagnetic energy which interrupts, obstructs, or otherwise degrades or limits the effective performance of equipment; and

2) Electromagnetic susceptibility of the appliance to disturbances in its environment, resulting in appliance malfunctions caused by static discharges, radio transmitters, cell phones or other nearby electrical or electronic devices. The term Immunity refers to the condition which exists when equipment operates within acceptable limits when exposed to electromagnetic environments imposed by an external source.

When a particular appliance is not generating excessive disturbances, and when it is operating correctly in the presence of such disturbances, the condition of electromagnetic compatibility is satisfied. Whether or not EMC is subject to government regulations in a particular market, EMC is an important design goal to assure reliable appliance operation and to avoid interference to nearby devices and radio services.

Over time, the nature of EMC considerations in the residential environment has changed. The introduction of digital circuitry into appliance designs has added narrowband, high frequency emissions to the possibility of broadband interference from DC motors and electromechanical switches. Electromagnetic susceptibility has been affected both by the use of potentially sensitive semiconductors in appliances, and by a residential environment that now includes many more disturbance sources such as cell phones, portable phones, remote controls and home entertainment electronics.

Electromagnetic Compatibility

Electromagnetic emissions Electromagnetic susceptibility


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Regulatory requirements

Background The regulation of electromagnetic emissions started with commercial radio broadcasting, so that interference with broadcast reception would be minimized. In the United States, the Federal Communications Commission (FCC) was established in 1934 to regulate broadcasting and interference. In the same year, the German “High-frequency device law” was published. Spectrum regulators in other parts of the world were established around this same time to deal with the rapid growth of the broadcast industry. To this day, emissions are regulated worldwide to prevent interference to radio and TV broadcasting, and sensitive services such as radio navigation and radio astronomy.

Immediately after radio receivers found their way into automobiles in the 1930’s, the subject of susceptibility arose – those receivers picked up interference from automotive ignitions and even static from the tires. Both sources of interference were quickly resolved, but the concept of EMC had been established. During the Second World War, the dense packaging and high power of military electronics accelerated the development of standards for both emissions and susceptibility.

Regulation of emissions from consumer devices grew mid-century with the advent of electrical household appliances and semiconductors, the latter enabling low-cost wireless remote controls and portable telephones. The digital electronics contained in personal computers that became popular during the 1970’s was found to generate potent radio interference. As a result, digital device regulations were established around the world – in the USA under FCC Part 15 Subpart J in 1979, internationally by the IEC standard CISPR 22 in 1985, and in the European Union under the EMC Directive in 1989.

EMC regulations now play an essential part in both governmental and private standards – to prevent radio interference and assure equipment functionality in aerospace, automotive, commercial, medical, military and residential applications. We will explore how “smart” appliances pose unique EMC challenges for both design and regulatory compliance.

EMC The regulation of EMC varies around the world by product use and jurisdiction. In the United States of America (USA), only the emissions of residential and commercial appliances are specified – adequate levels of susceptibility or immunity are left to the


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marketplace to determine. Emissions-only regulations for residential and commercial products are also found in Australia, Canada, China and Japan. Some common residential and commercial emissions standards are listed in Table 1 below:

Product type USA European Union International

Household appliances - EN 55014-1 CISPR 14-1

Audio/visual, broadcast receiver 47 CFR Part 15 EN 55013 CISPR 13

Information technology (ITE) 47 CFR Part 15 EN 55022 CISPR 22

ISM (Industrial, Scientific, Medical) that generates radio-frequency energy

47 CFR Part 18 EN 55011 CISPR 11

Table 1 – Common residential and commercial emissions standards

In the European Union (EU), regulation of both emissions and immunity for residential, commercial and industrial products of all types is in force, to assure the free movement of goods among member states. South Korea has also adopted the more comprehensive approach of the EU. The most common residential and commercial susceptibility/immunity standards are listed in Table 2 below:

Disturbance type Common source European Union International

ESD (Electrostatic Discharge)

Static buildup EN 61000-4-2 IEC 61000-4-2

Radio-frequency Radiated Immunity

Broadcast stations, consumer wireless > 80 MHz

EN 61000-4-3 IEC 61000-4-3

EFT/B (Electrical Fast Transient Burst)

ac branch switch arcing EN 61000-4-4 IEC 61000-4-4

Surge Lightning-induced EN 61000-4-5 IEC 61000-4-5

Radio-frequency conducted Immunity

Broadcast stations, consumer wireless < 80 MHz

EN 61000-4-6 IEC 61000-4-6

Power line magnetic immunity

ac power wiring EN 61000-4-8 IEC 61000-4-8

Power line variations Ac branch load switching EN 61000-4-11 IEC 61000-4-11

Table 2 – Common residential and commercial immunity standards


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Emissions - USA In the USA, the FCC exempts from its technical regulations appliances that contain “incidental radiators” such as switches and motors. Only appliances containing radio frequency (RF) or digital circuitry – defined as having clocks or oscillators operating above 9 kHz – fall under Part 15 rules, and even then there are additional

exemptions under which the digital circuitry in appliances may fall:

• Power consumption below 6 nanowatts (nW); this would apply to most calculators and some digital clocks.

• Battery-operated only, and having an operating frequency below 1.705 MHz.

• Used exclusively in transportation vehicles; these are subject to other industry standards.

• Digital devices used in large motor-driven appliances such as dishwashers and air conditioners.

This last exemption to Part 15 regulation – digital circuitry used exclusively in appliances – was intended only for large appliances, but has been widely misinterpreted to apply to all appliances. The FCC allowed the exemption on the basis that their large motors effectively mask any emissions produced by the low frequency microprocessors they employ. There is no such basis for exempting a hair dryer, rice cooker or massager.

Notwithstanding any or all of the exemptions listed above, the appliance manufacturer is obliged to assure that his devices do not cause interference to radio or TV. FCC Part 15.103 states:

The operator of the exempted device shall be required to stop operating the device upon a finding by the Commission or its representative that the device is causing harmful interference. Operation shall not resume until the condition causing the harmful interference has been corrected. Although not mandatory, it is strongly recommended that the manufacturer of an exempted device endeavor to have the device meet the specific technical standards in this part.

The simplest way for the appliance manufacturer to comply with the intent of 15.103 is to have the appliance tested for compliance with either the Class A (non-residential limits) or Class B (residential limits), if there is any possibility that the appliance may be


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causing interference. Appliances intended for use in the home would, of course, be subject to Class B emission limits.

Appliances that use RF energy to do some kind of work (such as heating or ionization) are subject to FCC Part 18 (ISM devices) rather than Part 15. Examples of such appliances are microwave ovens, wireless battery chargers and compact fluorescent lamps. The emission limits and measurement procedures under Part 18 are different from those of Part 15, and the product labeling is different too. FCC regulations for appliances are summarized in Table 3 below.

FCC EMC regulations, appliances:

emissions immunity example

no digital circuitry n/a* n/a hair dryer

with digital circuitry 15 subpart B** n/a setback thermostat

with ISM function Part 18 n/a microwave oven wireless charger RF lighting

* but cannot cause interference. ** only large appliances are exempt.

Table 3 - FCC regulations applicable to appliances in the USA

FCC rules, including Parts 15 and 18, are available online at: http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?&c=ecfr&tpl=/ecfrbrowse/Title47/47tab_02.tpl

Emissions - Japan

As with the FCC in the USA, residential appliances intended for use in Japan are subject to compliance only with emission requirements; susceptibility is not regulated but is left to the marketplace. Self-declaration of conformity to the Electrical Appliance and Material Safety Law ("DENAN") is appropriate for

most electrical appliances. Transition deadlines of March 31, 2006 to March 31, 2011 from the prior Material Control Law to the present DENAN are largely past. The emission limits are drawn from IEC CISPR standards and are summarized in Table 4.


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Japan EMC regulations, appliances:


no digital circuitry CISPR 14:1993/A1:1996

n/a hair dryer

audio-visual CISPR 13:1996/A1:1998

n/a CD player

with digital circuitry CISPR 22:1993/A1:1995

n/a computer

with ISM function High-frequency appliances (ISM)

n/a microwave oven

Table 4 - EMC regulations applicable to appliances in Japan

Appliances in Japan are not subject to the low-frequency harmonics (EN/IEC 61000-3-2) and flicker (EN/IEC 61000-3-2) emission limits that apply in the EU. These standards are discussed more fully in the EU section below.

Emissions - Australia

Australia does not impose susceptibility or immunity requirements under its EMC Framework. Rather, the Australian Communications and Media Authority (ACMA) recognizes a wide variety of joint Australian/New Zealand (AS/NZS), IEC, CISPR and CENELEC standards for self-

declaration and C-tick marking connoting EMC compliance. Earlier versions of standards are superseded on clearly-defined dates posted on ACMA’s EMC Standards List at http://www.acma.gov.au/WEB/STANDARD/pc=PC_310707. AS/NZS CISPR 14.1 (appliances emissions) and AS/NZS 61000.6.3 (generic) are the most appropriate standards for compliance, as well as AS/NZS CISPR 22. As with Japan, appliances in Australia and New Zealand are not subject to the low-frequency harmonics (EN/IEC 61000-3-2) and flicker (EN/IEC 61000-3-2) emission limits that apply in the EU.


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Designs for emissions compliance “Smart” appliances will contain some digital circuitry. The key design features to meet emissions compliance are:

For AC conducted compliance:

• consider bypass capacitors across the ac line, or a modular line filter for more severe noise

• use a common-mode choke to attenuate higher frequency conducted emissions.

• assure that any third-party switching power supplies already meet emission limits

For RF radiated emission compliance:

• use the lowest-power and slowest speed logic circuitry possible

• keep the circuit layout as compact as possible

• physically separate clock/driver circuits from I/O circuits as much as possible

• use capacitive bypassing or ferrite beads on lines leaving the circuit board

• use the appliance enclosure for shielding or signal grounding, if it is metallic

• for non-metallic enclosures, use an internal shield for severe interference

Emissions and Susceptibility - EU In the European Union, both appliance emissions and susceptibility or immunity are regulated under the EMC Directive 2004/108/EC for the purpose of CE-marking by “harmonized” standards that are listed periodically by the European Commission at:

http://ec.europa.eu/enterprise/newapproach/standardization/harmstds/reflist/emc.html

These standards are drawn largely from those published by the European Organization for Electrical Standardization CENELEC. It should be noted that these standards are not mandatory, but if they are used to demonstrate compliance then conformity is presumed.

The EMC Directive and its official interpretations allow many fewer exemptions than FCC rules, but appliances that contain inherently “benign” components do not need to be tested. Such “benign” components include passive resistance loads, ac induction motors, simple quartz watches, incandescent lamps, home and building


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switches that do not contain any active electronic components and passive antennas used for TV and radio broadcast reception.

The harmonized emission and immunity standards in the EU that are commonly applied to appliances are shown in Table 5 below.

RF interference and immunity, EU appliances


general EN 55014-1 EN 61000-3-2 EN 61000-3-3

EN 55014-2 hair dryer

with ISM function EN 55011 EN 61000-3-2 EN 61000-3-3

EN 55014-2 microwave oven

with digital function EN 55014-1 EN 61000-3-2 EN 61000-3-3

EN 55014-2 setback thermostat

Table 5 - CENELEC standards applicable to appliances in the EU

The emissions standard EN 55014-1 requires ac conducted measurements similar to FCC Part 15, EN 55011 and EN 55022. However, it uses as a proxy for radiated emission measurement above 30 MHz an absorbing clamp or ferrite transformer that is moved along each appliance cable, including the ac power cable. Use of the absorbing clamp to measure disturbance power is predicated on the assumption that most of the radiated interference from appliances smaller than 1m on a side propagates along its cables and not out from the enclosure.

Appliance measurements using the absorbing clamp are further detailed in the IEC standard CISPR 16-2-3. The method is quicker than radiated emissions measurements, and the test site requirements are also simpler. A diagram of disturbance power emissions measurement on an appliance using the absorbing clamp is shown in Fig. 1:


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Figure 1 – Absorbing clamp used to measure appliance emissions.

The emissions standard EN 55014-1 allows for the possibility of digital circuitry in the “smart” appliance, but the possibility of digital emissions above 300 MHz is not foreseen in the standard. It does include radiated emissions limits and methods, but only for toys.

If the appliance contains sources of emissions above 300 MHz, not necessarily a “smart” appliance but more likely in that case than otherwise, it is prudent to include EMC testing to a radiated emissions standard in addition to EN 55014-1. Reasonable choices would be either EN 55022 (for information technology equipment) or EN 61000-6-3 (generic emissions for residential, commercial and light industrial environments – the radiated emission limits are identical to EN 55022).

Several years ago a British importer of hair dryers was fined £6000 because two hair dryers, when tested for compliance to the “essential requirements” of the EMC Directive, failed the disturbance power limits of EN 55014-1 by up to 8 dB, but they also failed generic radiated emission limits by 19 dB. The hair dryers also caused visible interference to TV reception. Many in the EMC community at this time were surprised that the UK authorities chose to apply an EMC test (radiated emissions) over and above the appropriate product family standard EN 55014-1 for the hair dryers. The UK


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authorities considered that EN 55014-1 was not sufficient. Therefore, careful consideration needs to be given to the appropriate EMC testing of “smart” appliances that are likely to generate high-frequency emissions.

Designs for disturbance power compliance The absorbing clamp used to measure disturbance power is sensing common-mode signals in the cable being tested. In order to reduce these common-mode signals:

• consider bypass capacitors across the ac line, or a modular line filter for more severe noise

• use ferrite beads or common-mode chokes on signal lines

• for any shielded (screened) cables, minimize the impedance between cable shield and appliance enclosure or ground; improve termination of cable shield to connector, and connector to appliance enclosure or ground.

Harmonic and flicker emissions Table 5 contains references to the low-frequency (< 2 kHz) standards EN 61000-3-2 (harmonic emissions) and EN 61000-3-3 (flicker emissions). These standards only apply to equipment in the EU drawing less than 16 A/phase. Related standards cover equipment with higher current consumption. EN 61000-3-2 and EN 61000-3-3 are so-called “horizontal standards,” in that they apply to all types of equipment within their scopes, including home appliances, in addition to other EMC standards.

Harmonic emissions occur when the appliance power supply imposes a distorted current waveform onto the ac line, typically through diode rectification or electronic switching. The effect of high harmonic emissions is not so much the disturbance of other equipment connected to the same ac line, but rather the potential for overheating of a branch circuit feeding other equipment that also generates harmonic emissions. EN 61000-3-2 specifies that appliances drawing less than 75 W are exempt, from testing, and that “professional” equipment rated above 1 kW is also exempt.

Flicker emissions occur when the appliance presents a slowly- and quickly-varying load to the ac line. Limits are based on the threshold of annoying flicker caused by a 60 W incandescent lamp connected to the same ac branch as the appliance. Note that flicker emissions are not regulated in the EU on the basis of disturbance to other appliances, but rather on the irritability to bystanders. EN 61000-3-3 specifies that tests need not be made on equipment which is unlikely to produce significant voltage fluctuations or flicker.


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In the example of a setback thermostat in Table 3, testing to neither EN 61000-3-2 nor EN 61000-3-3 would be applied, because either: (a) the thermostat is battery-powered and not connected to the ac line, or (b) if ac-powered it consumes less than 75 W and by itself is unlikely to produce significant flicker emissions.

Designs for harmonic and flicker emissions compliance For harmonic emissions compliance:

• do not use a linear ac power supply > 75 W; use a power-factor-corrected (PFC) switching supply.

For flicker emissions compliance:

• use solid-state and soft-start techniques for switching loads

• where real loads must be switched on and off, consider transferring to equivalent dummy loads.

Appliance susceptibility and EN 55014-2 The harmonized product family standard EN 55014-2 draws on most of the common EMC disturbance tests and applies them selectively, depending on the technology in the appliance. Four categories are defined, as shown in Table 6 below:

Category I

Category II Category III Category IV

circuitry No electronic control circuitry

Electronic control circuitry, clocks <

15 MHz

Battery-powered, clocks < 15 MHz

Everything else

examples Tools, thermostats

Motor-operated appliances, toys

Electronic toys

Table 6 – Appliance categories defined in EN 55014-2


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Based on these categories, EN 55014-2 then defines which disturbance phenomena are to be applied to the appliance during testing, which performance criteria must be met, and the levels of the disturbances. The tests to be applied by category are shown in Table 7 below:

disturbance Category I Category II Category III Category IV

ESD n/a B B (C, some

toys) B

RF radiated n/a n/a A A

EFT/B n/a B n/a B

Surge n/a B n/a B

RF conducted n/a A (230) n/a A (80)

Mains variations n/a C n/a C

Table 7 – Applicability of susceptibility tests by appliance category

If the appliance contains no electronic control circuitry, no disturbances are applied. The appliance is deemed to comply without testing. The performance criteria are:

A - performs as intended during and after test A (80) - criterion A, with upper limit of testing 80 MHz. A (230) - criterion B, with upper limit of testing 230 MHz. B - may degrade during test, returns to normal after test. C - test may cause loss of function, which may be self-recoverable or by

operator action Examples of permissible degradations in performance, in terms of measurable appliance parameters such as speed, torque, etc. are also given in EN 55014-2.


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The reference standards and test levels specified in EN 55014-2 are given in Table 8 below:

EMC disturbance reference standard test level

ESD EN 61000-4-2 4 kV contact, 8 kV air

RF radiated EN 61000-4-3 3 V/m. 80% modulated

EFT/B transients EN 61000-4-4 0.5 kV signal lines, 1 kV ac lines

Surge EN 61000-4-5 1 kV differential, 2 kV common mode

RF conducted EN 61000-4-6 1 V signal lines, 3 V ac lines

Mains variations EN 61000-4-11 100% interrupt, 0.01s; 60% dip, 0.2s; 30% dip, 1s.

Table 8 – Overview of EN 55014-2 EMC tests and levels

Just as we saw with the appliance emissions standard EN 55014-1, when “smart” functions are added to the appliance, additional susceptibility tests to those listed above may be needed to assure reliable operation and compliance with the essential requirements of the EMC Directive.

Designs for susceptibility/immunity compliance ESD

• for metallic enclosures, assure good contact all along seams

• for non-conductive enclosures, assure no gaps

• keep sensitive wiring away from conductive enclosure

• provide capacitive bypassing and clamping components for wiring entering circuit boards

RF radiated

• use metallic enclosure for shielding, or provide internal shielding

• provide ferrite beads and/or capacitive bypassing for sensitive wiring on or entering circuit board

• keep circuit wiring and boards as short as possible EFT/B

• use capacitive bypassing or modular filter on ac power entry and cables > 3m

• place bypassing or filtering of ac power entry as close as possible to enclosure boundary

• use capacitive bypassing or ferrite beads on internal wiring that is susceptible


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Surge

• use capacitive bypassing or modular filter on ac power entry

• use clamping components at power entry, to limit surge energy RF conducted

• use capacitive bypassing or modular filter on ac power entry and cables > 3m Mains variations

• assure adequate frequency response and energy storage in power supply

Communications One way to enhance the functionality of home appliances is to endow them with the capability of communicating with a home computer, phone line or each other. The designer’s choice of whether radio or powerline communications is the medium is constrained by the performance characteristics of each and national regulations that vary from place to place. In any case, it is usually possible to embed an approved or compliant communications module into the appliance, minimizing the design time and regulatory compliance effort. There are often additional EMC or radio tests necessary to assure compliance of the “smart” appliance with the installed communications module.

Powerline communications Power wiring is everywhere in the home, and products have been developed to use it as a communications bus. However, the ac wiring generally carries a great deal of induced noise from network switching equipment, other home appliances and electronics and radio transmitting sources that couple into the wiring. As a result, reliable powerline communications (PLC) with the home typically use robust encoding such as spread spectrum technology to superimpose control or data signals on the ac line. Industry standards govern the signaling protocols, but regulatory compliance falls under spectrum regulators such as the FCC.

In the USA, home powerline communications falls under the Part 15 category of carrier current systems. They are regarded as “unintentional radiators” subject to the rules in 15.109(a), (e), and (g) and the general radiated emission limits in 15.209. The FCC’s Class B radiated emission limits can be used to assess compliance of an installed system, or CISPR 22 Class B as an FCC-accepted alternative. The only ac conducted emission limit is 1000µV (60 dBµV) over the AM broadcast frequency range 535 – 1705 kHz. There are no regulatory compliance requirements for susceptibility or immunity.


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In Canada, residential and office powerline communications are regulated under ICES-006. For systems operating above 1.705 MHz the radiated emission limits are identical to FCC limits. However, below 535 kHz ICES-006 imposes limits on carrier current output voltages that do not exist in FCC rules. Both the FCC and Industry Canada require verification of carrier current systems in three separate locations.

The regulatory situation for powerline communications in the EU presently divides at the signaling frequency of 148.5 kHz. Harmonized standards exist for both emissions and susceptibility below that frequency, but for broadband powerline communications above 1 MHz only an immunity standard is available as shown in Table 9 below:

Signaling range Harmonized emissions standard Harmonized immunity standard

95 – 148.5 kHz EN 50065-1 EN 50065-2-1

1.6 – 30 MHz none EN 50412-2-1 Table 9 – EU powerline communications standards

EN 50065-1 is a complex emissions standard that divides the operating range 95 – 148.kHz into several sub bands, two of which require a signaling protocol. Thus it is limited to low-frequency control and data applications.

While the European Commission has emphasized that all such systems must meet the essential requirements of the EMC Directive, little guidance is available on how to do that for systems operating above 1 MHz. Amendments to CISPR 22 are underway to accommodate higher levels of conducted emissions for PLC systems than those allowed by the present ac conducted limits.

Radio For the “smart” appliance designer looking at wireless communications, there are several system architectures of interest:

Short/medium range low-power radio link(s) appliance-to-appliance or appliance-to-PC

Long range low-power radio link(s) in appliance(s) to public telephone (PSTN) gateway low-power radio link(s) in appliance(s) to PC-to-Internet low-power radio link(s) in appliance(s) to cellular modem in PC or freestanding cellular modem(s) in appliance(s)


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By exploiting the use of a PSTN or Internet gateway, wireless links (and also powerline buses) allow appliances to be interrogated by the owner at any location over a secure path; or permit the appliance to report impending or actual failure modes to a central repair facility; or to be shut down by the local utility over a “smart grid” to reduce peak demand or take advantage of off-peak pricing.

If powerline communications is hampered by differing national regulations, radio communications is similarly burdened, except that:

• there are a few short-range radio bands available more-or-less globally, such as 2.4 GHz (including such IEEE 802 protocols as Bluetooth, Wi-Fi and Zigbee)

• embedded cellular modems are available to individually satisfy most national spectrum allocations

Some generally available wireless frequency bands and regulations are listed in Table 10 below

Frequency band FCC Industry Canada EU

Low-power, short distance (1 – 10m)

433.92 MHz 15.231* RSS-210 A.1* EN 300 220

2.45 GHz 15.249 RSS-210 A2.9 EN 300 440

Low-power, medium range (10 – 100m) high-speed data

2.45 GHz 15.247 RSS-210 A.8 EN 300 328 EN 300 440

5 GHz 15.401 A.9 EN 301 893 * Protocol requirements on type of communication and transmission rate. Table 10 – A sample of wireless regulations for common frequency bands

The corresponding standards for some public telephone (PSTN) interfaces are:

FCC 47 CFR Part 68, TIA-968-B Canada CS-03 EU ES 203 021-1, -2 and -3

Under the EU Radio and Telecom Terminal Equipment (RTTE) Directive 1999/5/EC, the only essential requirements for terminal interfaces are EMC and safety. Therefore the ETSI ES standards listed above are discretionary but recommended. For a telephone


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terminal interface in the EU the typical mandatory standards would be EN 55022 (emissions) and EN 55024 (immunity) and EN 60950-1 (safety).

The essential requirements for radio equipment under the RTTE Directive include EMC, safety and spectrum protection. Therefore in addition to the spectrum standards listed in Table 10 for the EU, there are these additional EMC standards:

Spectrum standard EMC standards

EN 300 220, EN 300 440 EN 301 489-1, -3

EN 300 328 EN 301 489-1, -17

EN 301 893 EN 301 489-1, -17

EN 301 489-1 is the core EU EMC standard for radio equipment that defines applicable EMC tests by equipment type, and performance criteria. The EMC tests are largely those listed in Tables 1 and 2 above. The EMC standards EN 301 489-3 and -17 apply specific setup and operating conditions appropriate to the frequency band and equipment.

There are no susceptibility/immunity requirements under FCC rules for the wireless bands above.

Designs for communications compliance • Assure that transmitter modules are already certified for the jurisdiction;

“compliant with” is not the same as “certified.”

• Appliances containing cellular modems will generally require approval by the cellular network operator, in addition to modem certification.

• Use the transmitter module in accordance with any user guidance or certification conditions; antenna choices may be restricted.

• Exercise care in selecting operating frequency bands; there are very few bands that are acceptable worldwide. On the other hand, a region-specific band may be less subject to interference than a more popular global one.

Product safety Appliance safety standards concern the hazards of shock, fire, heating, and similar physical phenomena. “Smart” appliances present no unusual EMC hazards except in four categories:

1. wireless appliances that can be used during life safety emergencies; related safety standards generally contain additional tests to assure the integrity of the wireless communications.


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2. appliances for use in the EU that can generate strong and potentially hazardous low-frequency electromagnetic fields.

3. “smart” appliances with embedded radios, where the combination of radiofrequency output power and proximity to the user is potentially hazardous.

4. “smart” appliances that use electronic circuitry for safety-critical functions such as motion or power shutoff.

Category 4 is addressed in the section below on Functional safety, and categories 2 and 3 are addressed in the section below on Electromagnetic exposure.

Functional safety The IEC standard series IEC 62508-1…-7 is directed at the structures for defining and reducing the hazards and risks associated with electrical/electronic/programmable electronic (E/E/PE) safety-related systems. The impact of functional safety on EMC is perhaps best captured in IEC 51508-2 clause 7.2.3.2(e), bold added:

e) the electromagnetic immunity limits (see IEC 61000-1-1) which are required to achieve electromagnetic compatibility – the electromagnetic immunity limits should be derived taking into account both the electromagnetic environment (see IEC 61000-2-5) and the required safety integrity levels;

NOTE 1: It is important to recognize that the safety integrity level is a factor in determining electromagnetic immunity limits, especially since the level of electromagnetic disturbance in the environment is subject to a statistical distribution. …For higher safety integrity levels it may be necessary to have a higher level of confidence, which means that the margin by which the immunity limit exceeds the compatibility level should be greater for higher safety integrity levels.

Thus the susceptibility/immunity levels specified in Tables 5, 7, 8 and 9 above may not be sufficient for safety-related functions implemented in “smart” appliances. The IEC 61508 series provides guidance for evaluating and designing to the appropriate requirements.

Electromagnetic exposure Strictly speaking, EMC refers to the harmonious operations of equipment with each other in the context of an electromagnetic environment. In many cases persons are part of that environment, and consideration must be given for “smart” appliances to any adverse effect of electromagnetic exposure on users and operators of that equipment. The nature of any electromagnetic threat varies by disturbance frequency, from skin surface currents at very low frequencies to cell heating at frequencies in the MHz and GHz ranges.


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National regulations for electromagnetic exposure generally divide by considering whether the exposure results as a natural byproduct of the operation of the appliance (such as a heating blanket) or whether there is an intentional radiating source of radio frequency (RF) energy present (radio transmitter). Table 11 details this division.

USA EU

Electromagnetic fields (EMF) as a byproduct of normal operation

Microwave ovens: 21 CFR 1030:

Leakage limit 1 mW/cm2 new, 5 mW/cm2 afterward. Otherwise: only guidelines (IEEE C95.1)

EU Council Recommendation 1999/519/EC; harmonized standard EN 50366 for appliances.

Radiated fields produced intentionally for communications

47CFR 1.1310, 2.1091, 2.1093. SAR evaluation for user distances < 20 cm. MPE evaluation for user distances > 20 cm

EU Council Recommendation 1999/519/EC; harmonized standards for radios such as EN 50360, EN 50371, EN 50385

Table 11 – Overview of USA and EU regulations for electromagnetic exposure

In practice, appliance EMF evaluation under EN 50366 in the EU is limited to frequencies below 400 kHz and therefore considers low-frequency effects. Radiated fields from transmitters in the USA, EU and many jurisdictions elsewhere are typically evaluated above 300 MHz, and involve high-frequency effects.

EU low-frequency EMF limits: EN 50366 The test procedures in EN 50366 measure magnetic flux density emanating from the appliance over the range 10 Hz to 400 kHz. The magnetic flux density limit at 50 Hz is 100 microTeslas (µT). For comparison, the earth’s magnetic field generates a steady-state or DC magnetic flux density from 30 µT to 60 µT.

The measurement distances for evaluation differ according to the typical separation between the appliance and the user, as in Table 12 below:

Measurement distance, cm

Appliance type

0 Electric blanket, dental hygiene, hair clipper, indoor whirlpool bath

10 Facial sauna, hair dryer, water bed heater

30 Dishwasher, washing machine, hand tool, microwave oven,


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refrigerator

50 Air conditioning unit, heater, clock, vacuum cleaner Table 12 – measurement distances in EN 50366 for evaluation of EMF

Compliance with EN 50366 is mandatory for appliances to meet CE-marking requirements for safety. There are no corresponding requirements in the USA.

Designs for EMF compliance Appliances with motors; working at high frequencies to 400 kHz; working with very high currents; evaluated at 0 cm

• Assure adequate magnetic shielding; twist or shield ac power feed and internal wiring

RF exposure from radios Owing to the popularity of cell phones, Bluetooth, Wi-Fi and other wireless devices, there are concerns about the health effects of such radios in close proximity to the user. Many jurisdictions have RF exposure rules for transmitters in place, including the USA, Canada, the EU, and Australia. Most of the rules are based on the heating effect of the RF energy on human cells, as the RF energy is non-ionizing and no other potential sources of cell damage have been conclusively observed.

The method of evaluation of RF exposure from a radio transmitter depends on its typical proximity to the user or others nearby. The information in Table 13 below is for US parameters but other jurisdictions are similar.


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User distance

Evaluation type method

< 20 cm Specific Absorption Rate (SAR)

1. Appliance with transmitter is placed near the body simulator filled with fluid approximating dielectric properties of brain or muscle.

2. Electric field inside body simulator is scanned to determine maximum power density or SAR from transmitter outside.

3. SAR limits do not vary with frequency, but with body part exposed. Hands, wrists and legs can dissipate heat better than head or body and have higher SAR limits.

> 20 cm Maximum Permissible Exposure (MPE)

1. RF power to antenna is measured. 2. Gain of antenna is considered to calculate maximum

power density at 20 cm or larger user distance.

3. MPE limits vary with RF frequency.

Table 13 – RF exposure evaluation of appliances containing radio transmitters

The graphical results of a typical SAR scan on a cellular handset are shown in Figure 2 below. Note that the place of highest SAR is at the base of the handset antenna:

Figure 2 – SAR scan of a cellular handset


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In most regulatory regimes, average transmitter powers of 20 mW or less do not require SAR evaluation regardless of the user distance. Transmitter power above 0.6 W approaches the upper limits of SAR for head-held devices such as cellular handsets.

Transmitters operating > 20 cm from users (and most installations in fixed appliances would fall in this category) would meet FCC 1.1310 MPE limits with 1 W power output and no antenna gain (0 dBi) from 30 to 300 MHz. Allowed power to meet MPE limits rises to 5 W from 300 to 1500 MHz and remains flat at 5 W above 1500 MHz. These power levels are reduced if the antenna gain is greater than 0 dBi.

Designs for RF exposure compliance • Use the lowest transmitter power consistent with reliable operation

• Multiple radio transmitter modules in one appliance may require additional RF exposure evaluation

For more information on specific testing and certification information, please contact Intertek at 1-800-WORLDLAB, email [email protected], or visit our website at www.intertek.com.

This publication is copyright Intertek and may not be reproduced or transmitted in any form in whole or in part without the prior written permission of Intertek. While due care has been taken during the preparation of this document, Intertek cannot be held responsible for the accuracy of the information herein or for any consequence arising from it. Clients are encouraged to seek Intertek’s current advice on their specific needs before acting upon any of the content.

Service Features:• Fast report turn around - Raw data available within 24 hours of test completion.

Report available in 48 hours.• Secure Website - Clients will be provided with a secure Website where data and

reports will be posted for their convenience.• Remote monitoring - We will provide a method of monitoring tests based on the clients needs:

-VHS-DVD-Live Webcam

EMC Testing:• SAE J1113-4 Conducted Immunity (BCI)• SAE J1113-11 Immunity to Conducted Transients on Power Leads• SAE J1113-12 Electrical Interference by Conduction and Coupling• SAE J1113-13 Immunity to Electrostatic Discharge• SAE J1113-22 Immunity to Radiated Magnetic Fields from Power Lines• SAE J1113-41 Test Limits and Methods of Measurement of Radio Disturbance Characteristics from Vehicle

Components and Modules• SAE J1113-42 Conducted Transient Emissions• SAE J551• OEM Specific Requirements as well, including GMW3100 GS, Nissan 28400 NDS, Mazda MES PA 66920• ISO 7637 Series (-1, 2, 3) Electrical disturbance by conduction and coupling• ISO 11452-4 Bulk Current Injection (BCI)• ISO 11452-2 Radiated RF Immunity (ALSE)• ISO 10605 Electrostatic Discharge (ESD)• European Directive 2004/104/EC

Emissions Tests:• Radiated Emissions• CISPR 25, Nissan, Ford, ISO, SAE, Fiat, Audi, GM, Chrysler,

Honda and many others• Use R+S Receiver ESIB 40 with low loss cables• AEMCLAP Certified measurements in our 5m Anechoic

Chamber from 10 kHz to 40 GHz• Conductive / Non-conductive table top• AEMCLAP Certified Site• 8' diameter turntable capable of handling 5000 lbs. Max.

Line Conducted Emissions• Horizontal and Vertical ground planes/5m Chamber

12, 600 sq.ft. facility. Expanded performance, vibration and EMC test capabilities and test equipment.

AEMCLAP AccreditationsBCI (Closed Loop/Substitution Method)

GMW3100/3097 para. 3.2.1.2.4GMW3097 Feb04 3.4.1ISO 11452-4SAE J1113-4Ford ES-XW-7T-1A278-ACChrysler DC 106141

ESDISO 10605SAE J1113-13GMW3100/3097 para. 3.2.1.4GMW3097 Feb04 3.6Ford ES-XW-7T-1A278-ACChrysler DC 106141

Radiated EmissionsCISPR 25SAE J1113-41GMW3100/3097 para. 3.2.1.1.2GMW3097 Feb04 3.3.1Ford ES-XW-7T-1A278-ACChrysler DC 106141

Radiated Immunity(ALSE)ISO 11452-2SAE J1113-21GMW3100/3097 para. 3.2.1.2.3GMW3097 Feb04 3.4.2Ford ES-XW-7T-1A278-ACChrysler DC 106141

7/06

Automotive EMC Testing

Immunity Tests:Electrostatic Discharge (ESD)• +/- 15 kV Contact Discharge, +/- 30 kV Air Discharge.• Humidity & Temperature controlled rooms and lab.• Waveform verification target with 1 GHz Oscilloscope.• Various ESD tips from standard IEC/EN test to tips designed for automotive.

Bulk Current Injection (BCI)• Use of dual directional power meter and probes for Forward, Reverse and

Net power measurements for every test.• Fixtures specifically designed per standards to improve repeatability• Specific equipment per standard used for testing to ensure proper testing

and repeatability• Can perform testing to Ford, GM, Chrysler, Fiat, Nissan, Honda, Mazda, Audi,

ISO or any other BCI standard.

Radiated Electromagnetic Fields (RF) • Tested in new 5m chamber.• Uniform field per IEC/EN specification.• Varity of modulations (AM, FM, Pulsed)• Field strengths designed for >600 V/m at a distance of 1m CW

or pulsed from 1-18GHz• Calibrated fields available up to 18 GHz

- 1kW amplifier from 80 MHz- 1 GHz- 250W amplifiers from 1 GHz - 18 GHz- 500W amplifier from 10 kHz - 200 MHz

Environmental Testing:• Temp / Humidity Chambers —

27 cubic feet; fully programmable 3°C/min ramp rates• Thermal Aging • Thermal Cycling• Thermal Shock– 16 cu. Ft. each chamber,

3 chambers (2-hot, 1-cold), chamber to chamber transfer time <5sec.- Temperature Range Hot Chamber: 71°C

to 210°C (160°F to 375°F)- Cold Chamber: -75°C to 190°C

(-103°F to 375°F)- Refrigeration: 25 to 30 horsepower

5m EMC ChamberSpecifications

• Certified from 10 kHz - 40GHz• Radiated Immunity from 80MHz - 18GHz

@ 200 V/m CW• Calibrated Uniform field all 16 points

from 26MHz - 18GHz• Radiated Emissions capable of 3m

and 5m measurements• Interior working dimensions of 30.1 feet

x 18.1 feet x 18 feet• Shielding performance greater than 100dB from 1kHz - 40GHz• 2m diameter turntable rated for 8,000 lbs• Floor rating of 8,500 lbs/sq ft or a total load capacity of over 10,000 lbs• Hydraulic lift capacity of over 10,000 lbs• Isolated shielded support room for clients support equipment• Separate shielded control room and isolated shielded amplifier room.• 8 foot by 8 foot door opening• Meets and exceeds requirements for 16 different standards.• CISPR 25 ground studs 90cm off floor• Air pressure @ 300PSI• Water/ Drain available @ street pressure• 200V/m fiber optic CCTV (Have access to viewing the product with a

fiber optic camera system that shows no effect due to the high field strength produced)

• Fiber optically controlled mast and turntable• Automated Radiated Immunity and Radiated Emissions testing capability

Available power

• 100 amps @ 120VAC 60 Hz single phase

• 100 amps @ 208VAC 60 Hz three phase

• 30 amps @ VARIABLE DC power

• 30 amps @ VARIABLE AC power

• 30 amps @ 480VAC 60 Hz three phase

• 30 amps @ 230VAC 60 Hz single phase

All power is independently filtered.

• 5M EMC Chamber— Capabilities from 26 MHz to 18GHz. Can be used for testing in accordance to: SAE, ISO, GM, Ford, Chrysler, Nissan, Audi, Fiat,Honda, Mazda, CISPR 25,11,16,22, SAE J1113, SAE J551

• Typical industry standards include Automotive, GM 5097, 3100, DC10614REV A, Ford AB/AC, Nissan, Mazda, Fiat, Honda, Audi, Chrysler, SAE,ISO, Mazda

• Peripheral support utilities are available: Compressed air (125 PSI @ 30 CFM, oiled or purified @ 2 Microns), Water (to 100 PSI), External gasventing (200 CFM), AC Power up to 240 VAC @ 50 Amps (50 or 60 Hz) single or three phase, DC Power up to 65 VDC @ 150 Amps. Full color internal monitoring system, with multiple camera angles provided.Generators, Chillers, Power Loads, Inert Gases, EMC hardened computers,can be made available.

• EUT (equipment under test) can be either tabletop or floor standing equipment.

Frequency Ranges Field Strength V/m Antenna

10 kHz to 30 MHz >200 E Field (between elements)

30 MHz to 2 GHz >200 Bi Log @ 1m distance

200 MHz to 18 GHz >200 Horn @ 1m distance

I n t e r t e k 1 - 8 0 0 - WO R L D L A B w w w. i n t e r t e k . c o m i c e n t e r @ i n t e r t e k . c o m

©2010 Intertek1/10

mailto:[email protected]

http://www.intertek.com

Intertek 70 Codman Hill Road

Boxborough, MA 01719

[email protected] 800-WORLDLAB www.intertek.com

The Ongoing Challenges in Automotive EMC Compliance


http://intertek.com/automotive/emc-testing/ 1

Contents

Introduction ..............................................................................................2

History .......................................................................................................3

The Changing EMC Environment.............................................................3

Changing EMC Test Requirements ..........................................................6

Summary ...................................................................................................7



Introduction

With advances in technology over the last decade, customer demand and OEM competition has forced automakers to try to integrate many of the latest technologies into their vehicles. Many of these technological advances, whether entertainment, communication or performance improvements, do succeed in bringing to the consumer a new level of comfort and convenience as well as enhanced safety features. But along with these features come new challenges to ensure EMC (Electromagnetic Compatibility) and device interoperability within the vehicle. EMC issues can result in minor annoyances such as unwanted noise through the entertainment system, as well as major issues such as loss of engine functions or control issues that could compromise the safety of drivers, passengers and the public. Add to this the growing demand of Hybrid Electric Vehicles (HEV) and Electric Vehicles (EV). These systems may bring a whole new set of concerns in relation to EMC. For these reasons, EMC is and will continue to be a very important topic of concern for the automakers’ present and future. There are two opposing forces at work influencing EMC in the vehicular environment. 1) The growing number of electronic components and modules for control, communications, and entertainment now being installed make achieving EMC far more demanding. 2) The force promising to bring the situation under control is the trend to replace complex vehicle wiring carrying analog, digital, and high-current signals with simpler, low-power signaling protocols. Between these two forces, engineers are modifying their predictive tools to keep up with changes at all levels – integrated circuit EMC evaluation, module EMC prediction and measurement, and whole vehicle characterization. As circuits operate at higher frequencies (and voltages), simulation methods have to adopt smaller grids for the accurate prediction of the resulting electromagnetic fields. As this process of modification is underway, the vehicle manufacturers need to assure that new modules have been tested to their respective EMC standards correctly and that the standards reflect the actual environment of future installation. While many vehicle EMC standards are non-governmental (and/or OEM specific) and therefore simpler to update, in the EU the Automotive EMC Directive 2004/104/EC contains its own requirements and is therefore more cumbersome to amend. Fortunately, it contains a number of international EMC standard references. With the recent surge of public awareness for a need for alternative vehicles such as EV’s and HEV’s , there are more independent auto manufacturers on the scene and they are starting to review their own EMC procedures and may see themselves developing their own standards based on their findings and business growth.



History

The popularization of the car radio in the late 1920s was the “canary in the coal mine” — the proverbial early warning— that automotive EMC would be an ongoing challenge. By the 1930s, a number of commercial radio brands were available. The early models were AM (amplitude modulation) only and very susceptible to both ignition noise and static buildup from the car’s tires. Both sources of disturbances were quickly overcome. Spark plug suppression was provided by resistive cables and resistive plugs; research on optimum spark plug suppression continued into the 1970s1. Conductive carbon was added to the car tires to prevent electrostatic charge buildup. In 1947, SAE J551, the first SAE (Society of Automotive Engineers) EMC standard, was published, but it was not until the proliferation of vehicular electronics in the 1970s that development of further vehicle EMC standards occurred.

The Changing EMC Environment

Today’s motor car contains an amalgam of legacy electrical/electronic functions and more recent devices – literally dozens of components or modules, sensors and actuators, and more than one network. Table 1 below lists typical functions and their attributes.

function history attributes

Airbag deployment Existing Critical

Braking control Existing Critical

Cabin environment Existing Comfort, Radio Noise, gage/warning function

Collision avoidance New Likely unlicensed radar 77 GHz.

Communications system

New Cellular, Bluetooth (800, 1900, 2400 GHz)

Emissions control Existing Environmental and legal concerns in some states

Engine ignition Existing Critical

Entertainment system New May include satellite radio receiver, FM modulator (low power 88-108 MHz).

Fuel injection Existing Critical

1“Relationship Between Spark Plugs and Engine-Radiated Electromagnetic Interference,” IEEE Transactions on Electromagnetic Compatibility, Burgett et. al.,August 1974, pp. 160-172.



Lighting system New Some Xenon discharge lamps.

Navigation system New GPS receiver

Noise cancellation New Comfort

Seat and pedal position Existing Critical

Security system Existing Short-range and Part 90 radio (170-300 MHz)

Stability control New Critical

Tire pressure monitoring

New Short-range radio

Transmission control Existing Critical

Table 1 Typical automotive electronic component or module functions.

Each of these functions exists in, and impacts, the vehicle’s EMC environment. For example, all of the control systems add to network/bus noise. Also, the communications, entertainment and security systems introduce radio sources while the GPS (global positioning systems) and satellite radio receivers require very low RF noise over their operating bands. Compounding these EMC challenges from the added electronic functions are the new factors associated with Hybrid Electric Vehicles (HEVs) and Electric Vehicles (EVs). Specifically, these include bus voltages exceeding 200 V, power inverter switching noise, and new bus/cable configurations. These issues are illustrated in the propulsion system block diagrams in Figure 1 and 2 for HEV and EV configurations.



Figure 1 Simplified HEV (Hybrid Electric Vehicle) block diagram.

Figure 2 Simplified EV (Electric Vehicle) block diagram.

In addition to the basics shown in these figures, there are the myriad modules, sensors, actuators, networks, and central control for the vehicle.

power

inverter

High

voltage battery

DC AC

DC/DC 12V battery

transmission

Electric motor Engine

12V battery

Power inverters and motors

High

voltage battery

Electronic

control unit

DC



Changing EMC Test Requirements

Existing EMC whole vehicle and module test standards cover the range of electromagnetic phenomena in conventional vehicles2. Vehicle manufacturers have adopted SAE and international standards to varying degrees and have established their own EMC standards that the testing laboratory must follow closely. Table 2 summarizes some of the relevant standards by reference number.

A sample of automotive EMC standards

parameter SAE GM Ford Toyota Int’l

EMISSIONS

Radiated RF

CISPR

25

J551/1, J551/5

TSC7026G

TSC7058G CISPR 25

Conducted RF CISPR 25 TSC7058G CISPR 25

Conducted transient

J1113-42

GMW3097

ES-XW2T-1A278-AC

CS-2009.1 _ ISO7637-2

RADIATED IMMUNITY

RF immunity

J551/1, J551/12, J551/16, J1113/28

TSC7025G ISO 11452-2, ISO 11452-3

Magnetic field immunity

J551/17

J1113-22

GMW3097

ES-XW2T-1A278-AC

CS-2009.1 TSC7001G ISO 11452-8

COUPLED TRANSIENTS

Inductive coupled

transients

J1113-12

GMW3097

ES-XW2T-1A278-AC

CS-2009.1

TSC7001G

ISO 7637-2

CONDUCTED IMMUNITY

Susceptibility J551/13

J1113-2,3,4

TSC7315G ISO 11452-4

Transient J1113-11 TSC7001G ISO 7637-2,

ISO 7637-3

ESD J551/15

J1113-13

GMW3097

ES-XW2T-1A278-AC

CS-2009.1 TSC7018G ISO 10605

2 “An Overview of Automotive EMC Standards, “Poul Anderson, IEEE EMC Symposium 2006 Proceedings, 2006, pp. 812-816.



Due to the high cost of performing whole-vehicle EMC testing and the need to expedite component integration, EMC testing is being performed at both the component or module and chip levels. The results are then used to predict compliance of the whole vehicle. Even without the added complexities of new HEV and EV propulsion systems, there are difficulties inherent in the existing test methods. At the chip or IC level, test standards such as IEC 61967-x family and SAE J145 2/3 do not fully predict installed EMC. The correlation between near- and far-field emissions may not hold, and the result is highly dependent on any external wiring harness. Also, at the module or component level, similar ambiguities exist. Component testing, however, can still be useful for identifying potential EMC problems. The introduction of HEV and EV propulsion systems clearly intensifies the challenges to existing test methods even more. High battery voltages reduce power transmission losses, but the resulting higher system impedances can render invalid emissions test results obtained with the artificial networks described in CISPR 253. Battery and drive motor impedance and impedance changes can also become an important factor in EMC. Worst-case RF emissions from vehicular power converters have been observed under transient conditions of load and speed4. Unfortunately, measurement standards have not yet taken this observation into account.

Summary

The automotive EMC environment is in a constant state of flux as new onboard electric devices, communications media (both wired and wireless), and new drive systems are added. Consequently, both EMC standards writers and vendors find themselves in a situation without fixed, agreed-upon testing procedures for assuring the compatibility of vehicles and components in hybrid and all electric cars. Ongoing change is the only constant. Automakers need to continue with strict attention to detail and try to model tests to capture the newer issues and concerns they come across. Component suppliers need to be aware of these concerns during their development cycles. Manufacturers of after market products and “cross over” devices, such as various kinds of IT equipment now being used in vehicles need to be cognizant of the requirements of the automotive EMC environments. Although automotive EMC standards are well-established by manufacturers and both domestic and international standards-making bodies, refinements may be

3 “High Voltage Automotive EMC Component Measurements Using an Artificial Network,” Nelson et. al.,IEEE Proceedings 18th Int. Zurich Symposium on EMC, 2007, pp. 195-200. 4 “HEV System EMC Investigation during Transient Operations,” Nelson and Aidam, IEEE Proceedings 18th Int. Zurich Symposium on EMC, 2007, pp. 205-208.



needed to achieve better correlation between chip-level and component- or module-level measurements and whole vehicle testing. New HEV and EV drive systems continue to add further challenge to automotive EMC testing. About Intertek

As a leading provider of quality safety solutions serving a wide range of industries around the world, Intertek has the expertise, resources and global reach to support its customers through its network of more than 1,000 laboratories and offices – 39 specializing in EMC testing – in more than 100 countries around the world. For more information regarding Intertek’s new developments, call 1-800-WORLDLAB or visit: www.intertek.com


EMC for Military & Aerospace Secure an efficient and cost-effective test partner

Intertek, a global leader in testing, inspection and certification, has completed significant upgrades to its Electromagnetic Compatibility Testing (EMC) labs to now perform mandatory EMC testing to commercial, military and aerospace requirements. We offer complete service, from initial project tendering stage and test plan origination, through to pre-compliance testing and timely final qualification report.

Our responsive team of experienced engineers and project support staff, are on-hand to advise, guide, and manage the whole process on your behalf.

We provide testing to MIL-STD 461, DO-160F and MIL-STD 810 standards at various locations within North America and Europe.

Intertek’s EMC testing facilities provide 10-meter and 5-meter semi-anechoic chambers to accommodate military products of all shapes and sizes. Our commitment to unrivaled service allows project completion within your target time-frames & smooth market entry.

Qualified Professionals With over 25 years experience in military and aerospace testing, Intertek engineers have the knowledge and experience to understand your industry needs.

Testing Capabilities

MIL-STD 461 • EMC Radiated Immunity

• EMC Radiated Emissions

• EMC Radiated Susceptibility

• Bulk Current Injection

• Conducted Immunity

• Conducted Emissions

• Conducted Susceptibility

MIL-STD 704

(Aircraft Electric Power Characteristics)

• DC-400 H2

• Normal and Abnormal Power Supply Condition Simulations

• Voltage Ranges:

o AC Systems: 115V

o DC Systems: 28 to 270V

MIL-STD 1179D (Lamps, Reflectors & associated Signaling Equipment for Military Vehicles)

• Photometric Testing

• Color Testing

• Blackout Visibility Testing

MIL-STD 810 • Materials Testing

• Vibration

• Thermal Shock

• Electrical Testing

• Mechanical Testing

• Altitude

• Temperature

• Humidity

• Salt Fog/Spray

• Immersion

DO-160 • Section 15 Magnetic Effect

• Section 16 Power Input

• Section 17 Voltage Spike

• Section 18 Audio Frequency Conducted Susceptibility – Power Inputs

• Section 19 Induced Signal Susceptibility

• Section 20 RF Susceptibility (Conducted & Radiated)

• Section 21 Emission of RF Energy

• Section 22 Lightning Induced Transient Susceptibility

• Section 25 ESD

Sample Projects

Federal Aviation Administration (FAA) R&D Performance Testing of Obstruction Lighting systems per FAA requirements in accordance with FAA Advisory Circulars.

US Army RDECOM ACQ CTR Testing of Advanced Combat Helmet (ACH) for PM Soldier Equipment according to government regulations in three phases.

MARCOSYSCOM Code GTES/PM Engineers Test for 3-Ton and 5-Ton capacity packaged Environmental Control Units (ECU) for the US Marine Corps Systems Command HVAC equipment.

For more information on EMC testing and certification for Military & Aerospace industries, call 1-800-WORLDLAB or visit www.intertek.com/emc/military-aerospace.

Intertek Testing Services 70 Codman Hill Road Boxborough, MA 01719

www.intertek.com 1-800-WORLD LAB [email protected]

EMC Compliance for Renewable Resource Power Systems


www.intertek.com 1

Contents Introduction ..................................................................................................... 2 Renewable Resources....................................................................................... 3

Biomass .................................................................................................... 3 Geothermal .............................................................................................. 4 Hydroelectric............................................................................................. 5 Solar energy.............................................................................................. 6 Photovoltaic (PV) ....................................................................................... 6 Concentrating solar power (CSP)............................................................... 7 Tidal power............................................................................................... 8 Wave power ............................................................................................. 8 Wind ........................................................................................................ 9

EMC Considerations....................................................................................... 10 Environments and Installations ................................................................ 10 Emissions ................................................................................................ 13 Susceptibility ........................................................................................... 16 Powerline communications...................................................................... 18 Wireless communications ........................................................................ 19

Summary ....................................................................................................... 20 About Intertek.............................................................................................. 21


www.intertek.com 2

Introduction

Renewable resources such as plants, sunlight, wind, rain and geothermal heat are naturally replenished over time – as distinguished from the finite resources coal, oil and natural gas. The market forces driving the development of renewable resources vary by region of the world, but they include:

• Reduction of greenhouse gases;

• Reliability of existing power network;

• Depletion of petrochemical sources;

• Local regulations, tariffs, subsidies and tax incentives. The scale of cost-effective power generation from renewable resources varies by type, and it can range from small rooftop photovoltaic (PV) solar cell installations generating a few kilowatts (kW) for local consumption (see photo below) to an offshore wind farm producing hundreds of megawatts (MW) peak and distributed over the high-voltage electricity grid to thousands of users. Often, renewable resource utilities will use more than one technology, to assure a more uniform supply of electric power over a 24 hour period. Not all renewable resources need to be converted into electrical power to be useful. For example, geothermal heat is widely used for both heating and cooling on a local basis. Fluid-filled solar panels can similarly provide home heating. Using the renewable resource to generate electricity, however, multiplies its versatility in terms of applications, customers served, and electrical utility power saved. In this paper we will focus on electricity generation using renewable resources. Each of these renewable resource electrical power systems has its own unique electromagnetic compatibility (EMC) characteristics – RF emissions and immunity - in addition to issues of environmental and electrical safety. Most jurisdictions around the world (in the USA for example, the FCC) regulate radio interference from electrical and electronic equipment, and many also govern immunity (as in the EU) to assure that the equipment continues to operate as intended in the presence of interference from other equipment including radio transmitters. Standards also cover EMC requirements for grid-connected or grid-tied power sources, where the renewable resource feeds electrical power back into the utility network.


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Renewable Resources

Today, renewable resources account for about 18% of the global electricity generation market. Some segments such as PV and wind power are growing more rapidly than others, but all segments are experiencing substantial investment. Estimates of the present capacity and potential for renewable resources are given in Table 1 below, followed by a brief overview of the most common renewable sources of electrical power. Total global electricity consumption is estimated at 15 TW, which can be supplied many times over by only partial realization of renewable resources.

Renewable source 2010 generating capacity,

Gigawatts (GW)

Global generating potential,

Terawatts (TW)

Biomass 54 46

Geothermal 11 22

Hydroelectricity 480 7

Solar photovoltaic (PV) 21

Solar concentrated (CSP) 500 1000

Tidal power 50 MW 10

Wave power 10 MW 2

Wind 175 72

Table 1 – Estimated global capacity and potential for renewable resource electricity generation.

Biomass The term biomass includes fuels derived from timber, agriculture and food processing wastes or from fuel crops that are specifically grown or reserved for electricity generation. Biomass fuel can also include sewage sludge and animal

manure. Biomass can be converted into other forms of energy through chemical processes such as fermentation, but for the purpose of electricity generation direct combustion is generally used. Some air pollution can be created, so biomass power plants may be less “green” than other renewable resources. Biomass is widely used for individual heating and cooking. It is estimated that 40% of the world’s cooking stoves use biomass. However, biomass power plants are typically utility-scale (output > 200 kW) and are not suitable for individual residential use. The photo at left depicts a 24 MW plant. Steam-electric generators, also used in fossil fuel power plants, provide the electrical power output


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from biomass plants. Although the power plants themselves are exempt from most EMC regulatory requirements (except to not cause interference), their internal control equipment performs critical functions that demand adequate immunity from industrial electromagnetic disturbances. The electrical output of the plant must conform to utility standards for power quality. Figure 1 illustrates a typical plant block diagram.

Geothermal Hot springs, geysers and ancient Roman baths are all examples of geothermal energy. This energy source can be tapped directly for individual residential purposes without generating electricity, by using heat pumps. At the utility level, geothermal power plants convert hydrothermal fluids (hot water or steam) to electricity. The oldest type of geothermal power plant uses steam, accessed through deep wells, to directly drive a turbine to produce electricity. Flash steam plants are the most common type of geothermal power plants in operation today. They use extremely hot water (above 300 degrees F), which is pumped under high pressure to the generation equipment at the surface. The hot water is vaporized and the vapor in turn drives turbines to generate electricity. Binary-cycle geothermal power plants use moderate-temperature water (100-300 degrees F). The water is used to vaporize a second fluid that has a much lower boiling point than water. The vapor from this second fluid is then used to drive the turbines to produce electricity. As with biomass generating plants, the geothermal power plants themselves are exempt from most EMC regulatory requirements; their internal control equipment performs critical functions that demand adequate immunity from industrial electromagnetic disturbances. The electrical output of the plant must conform to utility standards for power quality. Figure 1 below illustrates a typical plant block diagram.


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Hydroelectric Many hydroelectric power plants use a dam on a river to store water. Water released from behind the dam flows downhill through a turbine, spinning it, which then turns a generator to produce electricity. Hydroelectric power does not require a large dam – some hydroelectric power plants use only a small channel to direct the river water through a turbine. A small or micro-hydroelectric power system (< 100 kW) can produce enough electricity for a home or farm. Water is 800 times denser than air, so it is a very efficient source of power where it is available. Small or micro-hydroelectric plants are often used off-grid, where the power will be consumed locally. DC generators or alternators can be used where AC power frequency is unimportant. If the hydro power is to be fed back into the utility grid, or otherwise where line frequency is critical, then the power plant must incorporate any of: 1) an automatic controller at its inlet valve plus an alternator, or 2) an induction generator synchronized to the utility power, or 3) a solid-state inverter accepting either DC or variable-frequency AC and synchronized to the utility power. The control systems in small or micro-hydroelectric installations may be subject to residential or commercial electromagnetic emissions limits, as well as immunity. Grid-connected or grid-tied systems are subject to utility power quality requirements. Large hydroelectric plants will generally be exempt from EMC standards, but their internal control systems must meet industrial EMC standards in order to provide adequate operating reliability.


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Hydroelectric storage – pumping water uphill for later release – is often used in conjunction with renewable resources that are periodic in nature, such as solar, in order to provide a more uniform flow of electrical power to the user. Solar energy Around the world, several kilowatt-hours per day of solar energy fall on every square meter on the surface of the earth. The exact amount depends on latitude and weather, but the total constitutes vastly more power than that presently consumed. The conversion of solar power into useful energy usually takes one of two paths: 1) direct use by heating, either locally with fluid-filled solar panels or at utility scale by concentrating solar power (CSP or solar thermal); or 2) using silicon photovoltaic (PV) panels to generate DC electricity either for residential purposes or at utility scale. The DC power is usually converted to AC power using solid-state inverters. Inverters are available with capacities ranging from a few kW for residential applications to MW for utility plants. Large-scale CSP is more efficient than PV at converting solar energy to electricity, but the difference is diminishing as solar cell technology advances. Photovoltaic (PV): A number of different silicon fabrication technologies (such as thin film, monocrystalline silicon, polycrystalline silicon, and amorphous) are used in assembling panels to convert solar energy to DC electrical power. The current-

voltage characteristics of each panel are a function of the incident solar energy, with output short circuit current and open circuit voltage increasing with increasing light level. Maximum power is derived from each panel when the product of voltage and current outputs are maximized. Most inverters intended for PV applications will have built-in power maximization circuitry. Most residential and utility scale solar PV

installations (such as the megawatt-scale installation shown above) keep their panels in a fixed orientation for the sake of simplicity, even though tracking the position of the sun can add up to 50% in output.


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The control systems and inverters in residential or small commercial PV systems are subject to residential or commercial electromagnetic emissions limits, as well as immunity requirements. Grid-connected or grid-tied systems must meet utility power quality requirements. Large PV plants will generally be exempt from EMC standards, but their internal control systems and inverters must meet industrial EMC standards in order to provide adequate operating reliability. Solid-state DC-to-AC inverters employ high-power switching circuitry, which can generate radiated and conducted interference unless adequately shielded and filtered.

Concentrating solar power (CSP) or solar thermal: Concentrating solar power

(CSP) technology is used solely in utility scale plants. It works by capturing the solar

energy with a number of concentrating mirrors or lenses, and uses the resulting

heat to create steam and then electricity by a turbine generator. The most

common forms for concentrating the

sun’s energy are linear solar troughs

(parabolic in cross-section), solar

dishes (similar to satellite dishes) and

solar towers surrounded by a field of

reflectors called heliostats as in the

photo here. Temperatures of up to

1,500˚C may be generated in an

intermediate heat transfer working

fluid that may be oil or molten salts,

and finally into steam for the turbine. Molten salts have the added advantage of

storing heat to generate steam during cloudy weather or at night.

Figure 1 also serves as the block diagram for the power generation part of CSP systems. The trough reflectors, dishes, heliostats and lenses used in CSP systems


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track the position of the sun during the day, to maximize solar power conversion. This adds some complexity to the overall system. CSP plants will generally be exempt from EMC standards, but their internal control and tracking systems must meet industrial EMC standards in order to provide adequate operating reliability.

Tidal power

Owing to the gravitational pulls of the earth’s moon and sun, ocean tides flow twice a day in and out of natural estuaries or man-made channels. This flow of

water can be harnessed by submerged turbines similar to wind turbines as a reliable source of electrical energy. Although a number of tidal power prototypes have been deployed, this is a relatively new technology and only one tidal power system, shown in the illustration at left, has been deployed commercially in the UK. The system can generate up to 1.2 MW of power; rotor blade angle control allows the system to generate regulated AC power for tidal flow in both directions. Tidal power plants themselves are exempt from most EMC regulatory requirements; their internal control equipment performs critical functions that

demand adequate immunity from marine electromagnetic disturbances, including shipboard radars. The electrical output of the plant must conform to utility standards for power quality.

Wave power

It has been estimated that favorable coastal locations contain about 50 kW per meter of shoreline in available wave energy. This energy is not as steady or predictable as tidal power; in fact, it has many of the same characteristics as wind power. A number of different approaches have been tried to harness wave power, but few have been commercialized so far. One method employs a float inside a buoy that moves up and down with the waves, working an internal plunger that is connected to a hydraulic pump. The pump drives a generator to produce electricity, which is sent to the shore by means of an undersea cable.

Owing to the variability of the power source, wind power systems are often grid-connected through a solid-state inverter that can assure constant AC frequency and waveform. Wave power plants themselves would be exempt from most EMC


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regulatory requirements; any internal control equipment would need adequate immunity from marine electromagnetic disturbances, including shipboard radars if located far offshore. The electrical output of the plant would have to conform to utility standards for power quality.

Wind

Wind power is similar to PV solar power in being available everywhere, and in being scalable from individual residential wind turbines at the kW level to utility plants generating 100 MW or more. The offshore wind farm at left can generate 300 MW, and includes its own offshore power substation. A typical individual wind turbine will include a rotor, gearbox and generator. The gearbox is used to

increase the slow rotational speed of the rotor to higher generator speeds suitable for providing AC line frequency power from an induction generator. Electronic rotor pitch control is often used, especially in large-scale systems, to optimize power generation efficiency and provide speed reduction and stopping under very high winds and for servicing. Single residential or farm turbines may

use a DC generator or alternator for battery recharging, or with a solid-state inverter for grid-tied or grid-connected power feeding. Typical wind power systems are shown in the block diagram in Figure 4 below.

The aggregated power from utility scale wind farms is converted to HV for transmission over the utility’s HV (> 100 kV) lines.


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The control systems and inverters in residential or small commercial wind power systems are subject to residential or commercial electromagnetic emissions limits, as well as immunity requirements. Grid-connected or grid-tied systems must meet utility power quality requirements. Large wind farms will generally be exempt from EMC standards, but their internal control systems and inverters must meet industrial (or marine, if located offshore) EMC standards in order to provide adequate operating reliability. Solid-state DC-to-AC inverters employ high-power switching circuitry, which can generate radiated and conducted interference unless adequately shielded and filtered.

EMC Considerations

Environments and Installations

In the USA, electromagnetic emissions are regulated by the Federal Communications Commission (FCC) in order to prevent interference to radio and TV broadcast reception, and to sensitive services such as radio astronomy and radio navigation. Susceptibility is not regulated by the FCC – but there are medical,

military, aerospace, automotive and some other industry standards. In the EU, both emissions and susceptibility are regulated under the EMC Directive 2004/108/EC to assure the free movement of goods.

Typical EMC environments can be classified by the severity of the electromagnetic disturbances normally found there (for susceptibility), and by the distance to the boundary within the operator’s jurisdiction (for emissions).

• Residential environments usually assume a boundary 10m away, and by household sources of disturbances. In the USA, residential emissions from RF and digital devices are regulated under FCC Part 15, Subpart B, Class B limits. In the EU, residential EMC requirements also extend to commercial and light industrial environments. Thus a home rooftop solar PV system containing electronics such as a solid state inverter falls under residential emission limits.

• Industrial environments are generally based on a 30m boundary, and have disturbances from high-power switchgear, arc welding equipment and similar electromagnetically-noisy sources. In addition, industrial environments are often differentiated from residential ones in being connected to a medium-voltage (MV) power transformer as opposed to a 120/240 V low-voltage (LV) distribution transformer. In the USA, industrial emissions from RF and digital devices are regulated under FCC Part 15, Subpart B, Class A limits.


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When electrical or electronic equipment is located in a large area under one jurisdiction, such as in a public utility or industrial plant, most interference problems from the equipment can be resolved within the area and without regulatory intervention. Hence the FCC exempts such equipment from its technical rules. The corresponding classification under the EMC Directive in the EU is a “fixed installation” to which CE-marking does not apply. Utility-scale biomass, CSP, geothermal and PV plants are not subject to FCC or EU EMC limits except for the general requirement to not cause interference. However, the control equipment within these plants performs critical functions and should conform to appropriate industrial EMC standards such as EN/IEC 60947-1 (low-voltage switchgear and controlgear) EN/IEC 61326-1 (process control and measurement), or IEC TS 61000-6-5 (immunity for power station and substation environments). The potential electromagnetic interactions between devices in an installation and with external influences are indicated in Figure 5 below. Disturbances can enter and exit equipment by way of AC or DC power wiring, or over signal and control cables. Radio frequency (RF) emissions can emanate from equipment enclosures and disturb nearby equipment, or exit the installation boundary to cause interference to radio/TV or other sensitive receivers not under the control of the renewable power system operator. Similarly, RF emissions from powerful broadcast stations or nearby cell phones can upset the monitoring or control systems of the renewable power system. When the components of a renewable power system (such as Unit 1 and Unit 2 in the figure below) do not interfere with each other, they are termed electromagnetically self-compatible.

Figure 5 – Potential electromagnetic interactions between equipment and environment.


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Table 2 below summarizes electronic equipment EMC standards for various environments for the USA and EU. Note that the scopes of US Class A and B emissions do not map directly onto the generic EU EMC scopes. Because renewable power systems generally include a variety of electronics that could fall under several different EU EMC standards, we have chosen to show the default or generic standards here.

USA - FCC EU – EMC Directive Environment

emissions only emissions immunity

residential Part 15 Class B

commercial

light industrial

EN 61000-6-3 (generic) EN 61000-6-1 (generic)

industrial

Part 15 Class A

EN 61000-6-4 (generic) EN 61000-6-2 (generic)

public utility or

industrial plant No interference No interference

Documentation of EMC

considerations

Table 2 – EMC standards for US and EU environments.

Renewable power systems that are connected to the electricity grid, whether residential or industrial, are subject to additional EMC requirements to assure that the grid is not exposed to needless distortion or interference. In the USA, UL 1741 applies to inverters, converters, controllers and interconnection system equipment for use with distributed energy resources such as small-scale photovoltaic and wind power systems. When these systems are grid-tied or grid-connected, UL 1741 specifies compliance with the requirements in IEEE 1547 (Interconnecting Distributed Resources with Electric Power Systems), which in turn calls out these susceptibility standards:

• IEEE Std. 37.90.2 (Withstand Capability of Relay Systems to Radiated Electromagnetic Interference from Transceivers); and

• IEEE Std. C62.41.2 (Recommended Practice on Characterization of Surges in Low-Voltage AC Power Circuits);

• Or, in place of C62.41.2, IEEE Std. 37.90.1 (Surge Withstand Capability Tests for Relays and Relay Systems Associated with Electric Power Apparatus); and

• IEEE Std. 62.45 (Recommended Practice on Surge Testing for Equipment Connected to Low-Voltage AC Power Circuits).

The net effect of these susceptibility standards is to impose EMC criteria similar to, and slightly more stringent than, EU EMC requirements for similar phenomena. For


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example, IEEE Std. 37.90.2 specifies a 20 V/m RF radiated immunity test, plus a keyed and 200 Hz modulated spot test, to simulate GSM cell phone effects. The comparable EU generic industrial susceptibility level is 10 V/m. In the EU, EN 50178 applies to all types of electronic equipment for use in power installations. Internally it refers to the generic residential, commercial and light industrial or industrial EMC standards comparable to those in Table 2. EN 50178 is harmonized to the Low Voltage Directive 2006/95/EC but not the EMC Directive. EN/IEC 61727 covers the utility interface characteristics of photovoltaic systems; it applies the flicker emission standards EN/IEC 61000-3-3 (< 16 A/phase) or EN/IEC 61000-3-11 (> 16 A/phase) to the interface, plus current distortion limits that fall under the category of EMC phenomena. EN 61727 is not harmonized or associated with any EU directive.

Emissions

Electromagnetic emissions may be intentional or unintentional. Intentional emissions include radio signals from broadcast stations, cell phones, and remote control keys; or signals over power lines to control lights and appliances. Unintentional emissions can arise from sources such as DC motor brush noise, electromechanical switching or digital circuitry in computers and power systems. Separate emissions standards apply to intentional and unintentional radiators. Induction motors and generators do not generate significant emissions, nor are they susceptible to most electromagnetic disturbances. Therefore, they are usually not a factor in renewable power system EMC considerations. The major sources of unintentional emissions in most renewable power systems are digital control electronics and solid state inverters. Both of these create emissions by rapidly switching internal currents. High harmonics of the fundamental switching frequencies are generated, up to tens or hundreds of megahertz. The inverter functions by chopping its input current into a series of pulses of

variable width (pulse width modulation, or PWM), where the width changes to approximate a power frequency sine wave, as in Figure 6. The pulse frequency is often in the range 15 – 20 kHz. The input current to the inverter may be d.c., as for a photovoltaic installation, or ac for a wind turbine. If it is ac, the current is first rectified and then chopped.

Figure 6 – Inverter switching waveform and output current

The high-frequency energy created by the chopping process, as well as the residual noise superimposed on the output current, must be adequately filtered to prevent


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excessive conducted and radiated emissions. EMC-compliant inverters usually contain robust EMI filters at their inputs, outputs and any signal or control connections. They are also well-shielded and employ other good EMC design practices. Any rapid change in electrical current can give rise to an electromagnetic emission. If the current is traveling over a circuit board trace or wire of suitable length, that conductor can act as an antenna and radiate interference into the surrounding space. Long cables such as power cords are efficient antennas for frequencies below 30 MHz, so RF interference below 30 MHz is generally measured directly at the cable port as a conducted emissions voltage. RF interference above 30 MHz is usually measured with an antenna as electric field strength. Equipment that can radiate strong magnetic fields below 30 MHz, such as Industrial, Scientific and Medical (ISM) devices, are also tested for RF interference using a magnetic loop antenna. The corresponding ISM emissions standards are FCC Part 18, EN 55011 and CISPR 11. The regulatory emission limits of FCC Part 15 and the EU generic emission limits are similar but not identical, as Tables 3. 4 and 5 below indicate. Key differences between the US and EU requirements are:

• The EU radiated emission limits are specified only up to 1 GHz; US limits can extend above 1 GHz, depending on the maximum frequency in the test item. Nevertheless, if a device in the EU can emit interference above 1 GHz, the EMC Directive requires additional testing.

• FCC and EU environment definitions are not identical (see Table 2).

• The EU generic standards specify measurement of telecom port emissions, and EN 61000-6-3 requires flicker and harmonic emissions. FCC Part 15 does not specify these.

• The EU generic standards include the measurement of impulse noise (clicks) more frequent than 5 per minute. These are not measured under FCC Part 15.


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measurement FCC Part 15 Class A EU EN 61000-6-4 industrial

Radiated emissions @ 10m

30-88 MHz 39 dBµV/m

88-216 MHz 43.5 dBµV/m

216-960 MHz 46.4 dBµV/m

Above 960 MHz 49.5 dBµV/m


230-1000 MHz 47 dBµV/m

Conducted emissions

on ac power port

0.15-0.5 MHz 79 dBµV QP

66 dBµV AV

0.5-30 MHz 73 dBµV QP

60 dBµV AV

0.15-0.5 MHz 79 dBµV QP

66 dBµV AV


60 dBµV AV

Conducted emissions

on telecommunications port No requirement

0.15-0.5 MHz 97-87 dBµV QP

84-74 dBµV AV


74 dBµV AV

43 dBµA QP

30 dBµA AV

Table 3 – Comparison of FCC and EU generic industrial emission limits. QP = Quasi-peak detector, AV = Average detector. Radiated emission measurements below 1 GHz use a QP detector.

measurement FCC Part 15 Class B EU EN 61000-6-3 residential

Radiated emissions @ 10m

30-88 MHz 29.5 dBµV/m


216-960 MHz 35.6 dBµV/m

Above 960 MHz 43.5 dBµV/m


230-1000 MHz 37 dBµV/m

Conducted emissions

on ac power port

0-2 kHz No requirement

0.15-0.5 MHz 66-56 dBµV QP

56-46 dBµV AV


46 dBµV AV

5-30 MHz 60 dBµV QP

50 dBµV AV

0-2 kHz rated current < 16A

harmonics IEC 61000-3-2

flicker IEC 61000-3-3

rated current > 16A

harmonics IEC 61000-3-12

flicker IEC 61000-3-11

0.15-0.5 MHz 66-56 dBµV QP

56-46 dBµV AV


46 dBµV AV

5-30 MHz 60 dBµV QP

50 dBµV AV

Table 4 – Comparison of FCC and EU generic residential emission limits. QP = Quasi-peak detector, AV = Average detector. Radiated emission measurements below 1 GHz use a QP detector.


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measurement FCC Part 15 Class B EU EN 61000-6-3 residential

Conducted emissions

on dc power port No requirement

0.15-0.5 MHz 79 dBµV QP

66 dBµV AV


60 dBµV AV

Conducted emissions

on telecommunications port No requirement

0.15-0.5 MHz 84-74 dBµV QP

74-64 dBµV AV


64 dBµV AV

30 dBµA QP

20 dBµA AV

Table 5 – EU generic residential emission limits where there is no corresponding FCC Part 15 requirement. QP = Quasi-peak detector, AV = Average detector.

Susceptibility

EN 61000-6-1 (residential, commercial and light industrial environments) and EN 61000-6-2 (industrial environments) apply to all types of power installations and equipment in the EU. In the USA, IEEE 1547 for distributed power resources contains several of the same types of EMC disturbances as the EU standards. Common sources for these disturbances are noted in Table 6, and a comparison of the susceptibility tests is given in Table 7 below.

disturbance Typical source of disturbance Test standards

Electrostatic discharge (ESD) Static buildup on persons IEC 61000-4-2

Radiated electric field Broadcast stations, cell phones IEC 61000-4-3, IEEE

C37.90.2

Electric fast transient bursts Power line switching transients IEC 61000-4-4

Surge Lightning-induced power line transient IEC 61000-4-5, IEEE

C62.41.2

RF common mode voltage Low-frequency radio stations IEC 61000-4-6

Power line magnetic field Nearby power line wiring IEC 61000-4-8

Power line dips and

variations Power line load variations and switching IEC 61000-4-11

Ring wave Power line switching and lightning-induced

transients

IEC 61000-4-12, IEEE

C62.41.2

Table 6 – Common electromagnetic disturbances and their corresponding test standards.


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Maximum disturbance amplitude in standard below

disturbance reference IEEE 1547 EN 61000-6-1

residential

EN 61000-6-2 industrial

Electrostatic

discharge (ESD) IEC 61000-4-2 X

4 kV contact, 8 kV

air 4 kV contact, 8 kV air

IEC 61000-4-3 X

3 V/m, 80-1000

MHz and 1.4-2.7

GHz, 80%

modulated at 1 kHz

10 V/m, 80-1000 MHz,

3 V/m, 1.4-2 GHz,

1 V/m, 2-2.7 GHz,

80% modulated at 1 kHz Radiated electric

field

IEEE C37.90.2

20 V/m, 80-1000 MHz,

80% modulated at 1 kHz;

20 V/m at 900 MHz, 200

Hz on-off modulation

X X

Electric fast

transient bursts IEC 61000-4-4 X

1 kV pulses at 5

kHz 2 kV pulses at 5 kHz

IEC 61000-4-5 X 2 kV, 1.2 x 50 µs 2 kV, 1.2 x 50 µs Surge

IEEE C62.41.2 6 kV, 1.2 x 50 µs X X

RF common mode

voltage IEC 61000-4-6 X

3 V, 0.15-80 MHz,

80% modulated at

1 kHz

10 V, 0.15-47, 68-80 MHz;

3 V/m, 47-68 MHz,

80% modulated at 1 kHz

Power line

magnetic field IEC 61000-4-8 X 3 A/m 30 A/m

Power line dips

and dropouts

IEC 61000-4-

11 X

100% dip for 0.5, 1

cycle;

30% dip for 25/30

cycles;

dropout for

250/300 cycles

100% dip for 1 cycle;

30% dip for 25/30 cycles;

60% dip for 10/12 cycles;

dropout for 250/300 cycles

IEC 61000-4-

12 X X

X

(2.5 kV at 1 MHz in IEC TS

61000-6-5 for power

stations) Ring wave

IEEE C62.41.2 6 kV at 100 kHz X X

Table 7 – Comparison of susceptibility or immunity tests for US grid-connected distributed power systems (IEEE 1547) and EU generic EMC standards which apply to both grid-connected and independent power equipment.

The testing specified in Table 7 under IEEE 1547 bears no relationship to any FCC EMC requirements; these are given in Tables 3 and 4. Rather, IEEE 1547 is requisite for product safety listing or certification under UL 1741 (covering inverters, converters, controllers and interconnection system equipment for use with distributed energy resources). By contrast, the generic EU EMC requirements EN


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61000-6-1, -2, -3 and -4 are harmonized to the EMC Directive and compliance provides a regulatory presumption of conformity. The EU harmonized safety standard corresponding approximately to UL 1741 is EN 50178. Powerline communications

In addition to the unintentional electromagnetic disturbances on ac power lines noted in Table 6, electric utility companies have for decades superimposed low-frequency signals on their medium voltage (~ 10-40 kV) and low voltage (< 1 kV)distribution lines for network monitoring and control. More recently, both utilities and subscribers are using power lines at high frequencies for Internet communications. These added signals may not be anticipated by common conducted susceptibility standards, so the grid-connected renewable resource equipment vendor needs to confirm functionality for these signals - whether or not the technology is being employed internally. Low-frequency signaling over power lines by power utilities has long been permitted in both the USA and EU. In the USA, such power line communications (or PLC) are regulated on a non-interference basis by the FCC under Part 15, section 15.113. The span may not include the subscriber or house wiring. The available operating frequency band is 9 – 490 kHz. In the EU, the available frequency band is 3 – 95 kHz and the corresponding harmonized EMC standards are: EN 50065-1 Signaling on low-voltage electrical installations in the frequency range 3 kHz to 148.5 kHz - Part 1: General requirements, frequency bands and electromagnetic disturbances. The maximum applied voltage limit is 134 dBµV or 5 V. The emission limits above 150 kHz are identical to those in EN 61000-6-3 (Table 4). EN 50065-2-3 Signaling on low-voltage electrical installations in the frequency range 3 kHz to 148.5 kHz -- Part 2-3: Immunity requirements for mains communications equipment and systems operating in the range of frequencies 3 kHz to 95 kHz and intended for use by electricity suppliers and distributors. The immunity test levels are similar to those in EN 61000-6-3 (Table 7), except that the magnetic immunity test level increases to 100 A/m. There are also harmonized susceptibility test standards for non-utility signaling over power lines: EN 50065-2-1 (residential, commercial and light industrial environments) and EN 50065-2-2 (industrial environments). These parallel the generic standards shown in Table 7.


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More recently, high-frequency signaling has been permitted over both utility distribution lines and domestic power wiring. The FCC rules governing RF emissions from utility-controlled medium-voltage (MV) and low-voltage (LV) lines are found in FCC Part 15 Subpart G for “Access Broadband over Power Line” or Access BPL, in the frequency band 1.705 – 80 MHz. The FCC limits address radiated emissions only, and use Part 15 Class A limits for MV systems and Part 15 Class B for LV systems. There are no FCC equipment susceptibility requirements. Acceptance of high-frequency or broadband over powerline communications in the EU has been impeded by the absence of any harmonized emissions standards that allow practical system operation. Emissions standards such as EN 55022, EN 61000-6-3 and -4 contain ac conducted limits that are too low to be useful. Nevertheless, a harmonized immunity standard has been published: EN 50412-2-1 Power line communication apparatus and systems used in low-voltage installations in the frequency range 1.6 MHz to 30 MHz -- Part 2-1: Residential, commercial and industrial environment - Immunity requirements The susceptibility or immunity levels required in this standard agree with the levels shown in Table 7 for both residential and industrial environments. In the USA, grid-connected renewable power systems such as distributed PV or wind power should target compliance with the most stringent combination of IEEE 1547 and EU generic EMC standards for the intended environment. The equipment should provide adequate filtering against any powerline carrier signals that may be in use, or – if the system is intended to respond to such signals - carefully route the signals only to intended receivers. If the renewable power system generates powerline carrier signals, self-compatibility must be assured. Wireless communications

Product EMC standards such as EN/IEC 60947-1 (low-voltage switchgear and controlgear) and EN/IEC 61326-1 (process control and measurement) provide generally adequate RF immunity from common radio transmitters as AM/FM/TV broadcast, cell phones, walkie-talkies and remote controls. Similarly, renewable resource systems comprising a number of different equipment types and evaluated to the requirements of the generic EMC standards EN/IEC 61000-6-1 and -2 will afford protection from performance degradation in the presence of most common RF interference sources.


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Additional EMC considerations may come into play when either the operating environment of the renewable power system or specific equipment configurations result in RF fields higher than those in the relevant EMC standards. For example: The system is deployed in a navigable waterway and may be exposed to shipboard radar (> 1 GHz) or low-frequency radio communications fields (0.1 – 27.5 MHz); The power system contains a radio telemetry or voice communications transmitter antenna in close proximity to other electronics; Operating and maintenance personnel are using handheld two-way radios while working in open cabinet enclosures. In each of these cases the potential maximum RF field should be compared with the tested immunity limits of the power system and its electronic components.

Summary

Renewable resource power systems contain the promise of environmental friendliness and petrochemical independence. In many parts of the world, such power systems are being encouraged by tax incentives and simplified regulation. Each type of resource considered here – biomass, geothermal, hydroelectric, photovoltaic, tidal, wave and wind – has its own advantages and drawbacks. Some, such as PV and wind, are well-suited to residential or distributed configurations. All, even the largest utility-grade power systems, are subject to EMC considerations for the sake of either regulatory compliance, reliable operation, or both. EMC regulations for renewable resource power systems vary widely around the world, but the US FCC and EU EMC regulations are fairly representative so they are examined here. The FCC does not generally regulate susceptibility or immunity of electronic equipment, but for grid-connected resources in the USA immunity is necessary for product safety listing or certification. In the EU, both grid-connected and independent power systems must meet EMC criteria.


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About Intertek -- Commercial & Electrical

Intertek Commercial & Electrical Services specialize in testing and certification for a wide range of products, including household appliances, electronics, automotive components, heating equipment and air conditioning, cable and wiring accessories, industrial machinery, medical equipment, lighting, semiconductors and manufacturing products for construction. We provide industry-specific certification services for electromagnetic (EMC) compatibility and specialized telecommunications.
