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

icenter@intertek.com 800-WORLDLAB www.intertek-etlsemko.com

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

www.intertek-etlsemko.com 1


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
EMI only:
Approval Verification
Certification N/A Certification
Procedures DoC: accredited
Cert: accredited
In-country
testing No No N/A No
required?
MRA with
N/A N/A N/A N/A
US?
For DoC only:
Marks None N/A N/A
FCC logo

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 EMI only:
Certification N/A Licensing
Procedures Verification
In-country
testing No No N/A No
required?
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 Certification and
N/A N/A Registration
Procedures Homologation
In-country
testing N/A Yes N/A No
required?
MRA with
Pending Pending N/A N/A
US?
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
Spectrum EMC Medical
EMC Competent
Authority Competent Competent Competent
Authority
Authority Authority Authority
Verification,
Verification. Verification.
DoC, Type
Approval Notified Body Notified Body
Verification Examination,
Procedures opinion may be opinion may be
Notified Body
obtained rendered.
approval
In-country No No No No
testing



required?
MRA with
Yes, Phases I & II Yes, Phases I & II Yes, Phases I & II Yes, Phases I & II
US?
CE, possibly
CE and Notified
Notified Body
Marks CE CE Body number
number, alert
where applicable
mark

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 Certification,
Certification Verification Registration
Procedures licensing
In-country
testing No Yes No Yes
required?
MRA with
No No No No
US?
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 Certification, Certification,
Registration Licensing
Procedures SDoC verification
In-country
testing No No No No
required?
MRA with
Yes, 2007 Yes, 2007 No No
US?
Class B: VCCI
mark Technical
Marks Conformity PSE or none None
Class A: Kanjii Mark
text

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
Certification; see
Certification; Certification; Certification;
Approval see: CNCA-08C-032
see: see: to 043 for
Procedures CNCA-07C-031
CNCA-01C-020 CNCA-01C-016 examples; also
for examples
Registration
In-country
testing Yes Yes Yes Yes
required?
MRA with
No No No No
US?
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 DoC and Certification,
Certification Licensing
Procedures certification registration
In-country
testing No No No No
required?
MRA with
Yes, Phase I Yes, Phase I No No
US?
Commodity Commodity
Marks NCC No
inspection mark inspection mark

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 icenter@intertek.com.
Intertek gets you the answers you need—within 24 hours. We look forward to helping you.


Insider’s Guide to Faster Safety & EMC Testing

Intertek Testing Services
70 Codman Hill Road, Boxborough, MA
www.intertek-etlsemko.com

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 icenter@intertek.com, or visit our website at www.intertek-etlsemko.com.

This publication is copyright © Intertek and may not be reproduced or transmitted in any form in whole or in part without the 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: icenter@intertek.com Web: www.intertek-etlsemko.com

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.

60 Fortunately, the EMC learning curve for products that fail
50 ITE
initially is quite steep. Presumably taking advantage of both
the EMC education provided by the first go-around, as well
40
Medical as the pinpointing of EMC problems, manufacturers reduce
30 the failure rate on the EMC re-testing to the level of 5% -
Learning curve – 7%. Very challenging products may require a third round of
Failure

20 plus
knowing exactly what EMC testing, for which we observe a failure rate reduced to
10 1% - 2%.

1st 2nd 3rd trial
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 EMC environment
interpretation of EMC environments can differ USA EU+
between jurisdictions. In the USA, the FCC has
defined the Part 15 Class A environment as
anything except residential or consumer. EU non-residential industrial
Class A
generic EMC regulations define Class B more
broadly. It may include commercial and light residential,
industrial environments. For ITE, however, it is Class B residential commercial,
acceptable to allow Class A emissions in light industrial

commercial and light industrial locations.
Emissions increase Immunity disturbances

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,
The design process
validated, tested and perhaps modified. The Design
concept Target System
feedback implied in Figure 3 does not necessarily rules
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 Regulatory Functional Initial
release evaluation design

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
bypass impedance Figure 4 for a leaded bypass capacitor. At low
frequencies the capacitive impedance
decreases as frequency increases, allowing for
10
good bypass characteristics. Above a resonant
point determined by the capacitor’s nominal
value and its internal and external lead
impedance, ohms

inductances, impedance increases with
1 frequency – reducing the capacitor’s
effectiveness at the higher frequencies.
Leadless bypass capacitors are more effective
at high frequencies owing to their lower
connection inductances.
0.1
0.01 0.1 1 10 The same argument can be applied to the
frequency, GHz parallel power and ground planes in a PC
board. These constitute effective bypass
capacitors with low inductances.


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
aperture shielding effectiveness to reduce RF emissions or improve immunity,
70
only if the enclosure is conductive (metal or
plastic) and preserves the continuity of a
shielding effectiveness, dB

60
conductive path around the electronic circuitry
50 inside. Any seams or holes in the enclosure
40 10 cm must be sufficiently small to attenuate
30 1 cm electromagnetic disturbances that could enter
or exit. Small openings (see Figure 5) can be
20
tolerated, depending on the frequencies of
10 concern. In this chart the dimensions of 1 cm
0 and 10 cm represent the diameter of a circular
0.01 0.1 1 10 opening, the diagonal of a rectangular opening,
frequency, GHz or the length of a thin slit or seam. Non-
conductive enclosures provide good 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


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
Pre-compliance EMI site excluded from the 1m pre-compliance site by constructing a
screened room around it using a wooden frame and metal
1m mesh. Radiated reflections will be introduced, so any
measurements made in the screened room are subject to
EUT analyzer additional uncertainties. The screened room can also be used
for conducted emission measurements using a LISN (Line
Impedance Stabilization Network) or AMN (Artificial Mains
floor - not a ground plane Network).

Pre-compliance tools – 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.


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.”


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