EMC Standards and Their Application
ETL SEMKO (Kista, Sweden)
Intertek Testing Services
Without EMCno market access! Yes, that is
the fundamental concept for manufacturers of electrical
apparatus and systems to remember. It is therefore
necessary to stay current on EMC requirements and
standards and to try to understand how each applies
to different types of equipment.
Regulations may be mandatory, like U.S. FCC
requirements and European EC Directives, or voluntary,
like VCCI approval in Japan. In either case, following
EMC regulations may impart a market advantage.
Standards are voluntary to use but are recommended
as a reference for verification of compliance with
regulations. Basic standards describe test procedures,
and in some cases test instrumentation and calibration
techniques, while more specific product or application
standards usually define limits, severity levels,
and compliance criteria. This article provides an
overview of EMC standards and their use for verifying
compliance with regulations.
Electromagnetic CompatibilitySome Fundamental
EMC stands for electromagnetic compatibility
and is defined as the ability of equipment to function
satisfactorily in its electromagnetic environment
without introducing intolerable disturbances to
anything in that environment. EMC requirements concern
two basic concepts: emissions and immunity or susceptibility.
Electromagnetic disturbance is any phenomenon
that may degrade the performance of a device, equipment,
or system, or adversely affect living or inert matter.
Electromagnetic interference (EMI) is the
degradation of the performance of a device, transmission
channel, or system caused by an electromagnetic
disturbance. In certain parts of the world, "EMI"
is used to characterize emissions. This may lead
to confusion when it comes to the characterization
of immunity, which is sometimes called EMC!
Electromagnetic disturbances can be conducted
or radiated, and the emissions and immunity requirements
are referred to in military standards (MIL-STD 461/462)
as CE/RE (conducted emission/radiated emission)
and CS/RS (conducted susceptibility/radiated susceptibility),
Disturbances may represent low-frequency (LF) and/or
high-frequency (HF) phenomena, as well as broadband
and/or narrowband. Broadband disturbances can originate
from commutator motors, ignition systems, arc welding
equipment, etc.; narrowband from digital electronic
circuitry, switched-mode power supplies, and radio
communication equipment. Computers have often been
reported to cause interference with radio services,
including police, aeronautical and broadcast services.
On the other hand, radio transmission by a high-frequency
carrier, such as a 900 MHz cellular or a 1.8 GHz
DCS, can cause problems in computers and all electrical
circuits because the carriers are easily picked
up by cables and apertures functioning as antennas
and are demodulated in electronic circuits by different
nonlinear electromagnetic phenomena.
To really understand how electromagnetic disturbances
emanate, propagate, and influence electrical systems,
one must have a thorough knowledge of electromagnetic
field theory and high-frequency phenomena. EMC represents
a broad field of technology and may represent a
new subject for many manufacturers of electrical
products. However, if one follows certain rules
of thumb regarding wiring, PCB layout, grounding
and shielding, and usage of RFI suppression components,
it is not difficult to cope with different EMC standards
In industry, it is assumed that electronic
control systems can be used in conjunction with
interfering switching operations, motor drives,
high-frequency ovens, welding equipment, etc. In
a car, electronic automatic systems must function
when we use our mobile phone or meet other vehicles
(with interfering ignition systems). An electronically
controlled wheelchair is presumed to function normally
even when the person sitting in the chair uses a
mobile phone or a portable PC. We demand that life-supporting
electromedical apparatus in a hospital function
safely even near high-frequencyradiating surgical
The general EMC requirements in the U.S.
are set by the Federal Communications Commission
(FCC), while the Food and Drug Administration (FDA)
regulates medical products. Mandatory FCC requirements
primarily concern computing devices, defined as
any electronic device or system that generates and
uses timing pulses at a rate in excess of 9000 cycles
per second and uses digital techniques. FCC Part
15 covers radio frequency devices capable of emitting
RF energy in the range of 9 kHz200 GHz. Testing
should be done according to ANSI C63.4-1992.
Part 18 covers industrial, scientific, and
medical (ISM) equipment (Figure 1), defined as any
device that uses radio waves for industrial, scientific,
or medical purposes and is not intended for radio
communications. While most FCC regulations only
concern emissions, FDA also requires immunity for
certain life-support equipment. FCC Parts 15 and
18 include regulations as well as technical aspects
and limits. FCC Part 68, which governs the technical
requirements for registration of telecom terminal
equipment, includes lightning surge tests (surge
|Figure 1. Required frequency range of radiated
FCC Part 15 currently has three different procedures
for showing conformance:
Verification, where the manufacturer
or the importer files a test report showing
Certification, which requires a review
of the application by the FCC, and the use of
a unique FCC identification number.
Declaration of Conformity (DoC), which
requires that tests are performed by a test
lab accredited by A2LA or NVLAP (other accredited
labs may also be accepted).
The following represents an example of
the FCC's classification system, where the correct
administrative procedure is listed according
to product type (Class A refers to nonconsumer
products, Class B to consumer products):
Personal computers and peripherals (Class
B): Certification or DoC.
Cpu boards and internal power supplies
used with personal computers (Class B): Certification
External switching power supplies (Class
A and B): Verification.
The FCC is currently reviewing these procedures
with the aim of simplifying them by reducing the
number of categories.
The European EMC Directive, 89/336/EEC, sets
out the legal requirements on EMC for principally
all electric/electronic equipment to be placed or
used in the Common Market/
European Economic Area. The European legislation
covers emissions as well as immunity.
The EMC requirements are valid for apparatus
and systems placed on the market as complete units.
Components such as resistors, transistors, or display
units are not included. However, components with
a direct function to the end-user, like plug-in
PC boards, are regarded as equivalent to apparatus
and have to follow the same rules (see Table I).
Scope of Regulation
Appliances and/or digital circuitry inside
|Automotive digital electronics
||Yes, Auto EMC Directive
|Devices with power
||No, except cpu boards and
||Yes, if it has a direct
||Yes, except for induction
||No, except TV interface
|Fluorescent lamps, fixtures
||No (unless RF ballast)
|Marine digital electronics
||Yes, Marine Equipment Directive
|Medical digital devices
||Yes, Active Implantable,
or Medical Devices Directives
|Controls in industrial plants
|Battery operated clock <1.705
|Digital devices, PCs, peripherals
|Amateur radio transmitters
||No, except commercial power
||No, except EMC for commercial
||Yes, Part 15
||ETS 300, 220, 328, 330,
440, 445, or national rules
|High power transmitters
||Yes, other FCC Parts
||ETSI or national rules
|Table I. Scope of FCC and EU
EMC regulations for unintentional and intentional
New EEC Directives only set out essential requirements
and legal aspects (New Approach). Technical aspects
are dealt with in specific standards, the application
of which is voluntary. These standards are developed
by specific bodies, such as CENELEC or ETSI, and
are harmonized to the directives by the action of
the European Commission. The EMC Directive itself,
however, is based on a presumption principle, which
means that a product that meets the requirements
of the harmonized standards is also presumed to
meet the essential requirements of the EMC Directive.
Under the General Agreement on Tariffs and
Trade (GATT) and its successor, the World Trade
Organization (WTO), member countries are obliged
to adopt international standards for national use
wherever possible. International standards concerning
EMC are primarily developed by the International
Electrotechnical Commission (IEC) and the International
Special Committee on Radio Interference (CISPR).
The new extensive series developed by IEC includes
terms, and conditions.
of electromagnetic environments.
and disturbance levels.
and measurement techniques.
and mitigation guidelines.
Some specific EMC standards have also been
published by the International Organization for
Standardization (ISO). North American EMC standards
are published by the FCC, the American National
Standards Institute (ANSI), and the Institute of
Electrical and Electronics Engineers (IEEE). Private
standards are submitted by Bellcore (for telecom
equipment), the Society of Automotive Engineers
(SAE) and automotive manufacturers, and the U.S.
Department of Defense.
European EN standards concerning EMC are
developed by the European Committee for Electrotechnical
Regulations and standards concerning telecom
and radio transmitting equipment are published by
the International Telecommunications Union (ITU)
and the European Telecommunications Standards Institute
International and European EMC standards
are to a great extent becoming harmonized, due to
the fact that many EN standards are based on IEC
and/or CISPR standards. There are also similarities
between international and U.S. standards, though
they are not equivalent. Figure 2 shows some intercompatibility
problems between similar emission standards (FCC
Part 15 J and CISPR 22 limits, respectively, measured
at a distance of 10 m). FCC, however, accepts conformity
to CISPR 22: 1985 as an alternative to FCC Part
15 (sections 15.107 and 15.109).
|Figure 2. Emission limits compared at a
measuring distance of 10 m.
|Figure 3. Required frequency range of conducted
EMC standards are continuously being developed
and revised, and the standards "jungle" sometimes
seems a bit difficult to get through. It is therefore
important to keep track of standards' publication
dates, in addition to knowing if a new standard
is to be expected in the near future and when an
old standard is no longer valid. The following dates
are of specific interest in regard to a standard:
date of publication (dop) and date of withdrawal
(dow) of a conflicting (earlier) standard. Draft
standards are sometimes called preliminary, for
example prETS or prEN. Temporary EN standards are
Standards are principally divided into the
following main groups:
Generic standards refer to the electromagnetic
environment in which the apparatus/system is to
be used. General standards concern groups of equipment
used for general applications in a specific environment,
like general telecom equipment and medical and laboratory
Basic standards describe measuring methods
and, in some cases, interference levels as well
as limits. One of these is the standard series IEC
801-X for process industrial applications, which
has been converted into a general series of basic
standards, IEC 61000-4-X, which were then translated
into European standards as EN 61000-4-X.
Product and Product Family Standards
These are applicable for specific product
types, which are specified within the scope of the
In addition to these standard documents,
there are also standards offering guidance on installation
techniques, or a code of practice, for example the
IEC 61000 series, Part 5 (IEC 61000-5-X).
EMC Standards Classification
Generic standards have two environmental
1. Residential, commercial, and light
industrial environments, including domestic, office,
laboratory, and light industrial environments where
the apparatus or system is connected to the public
2. Industrial environments, meaning
"heavy" industrial environments with separate transformer
stations for mains supply, usually with equipment
spread over some distance.
This simplified view of the world as one of two
categories does not hold true in all cases. There
are so-called gray zones such as laboratory or hospital
environments where equipment may be connected either
to the public mains or to an in-house power net,
through a separate transformer station.
CISPR standards concerning emissions, and
to some extent corresponding EN standards, have
a classification according to the following:
Information Technology Equipment (ITE) intended
primarily for use in domestic environments and may
include portable equipment, telecommunications terminal
equipment, personal computers, and auxiliary connected
ITE, which satisfies Class A but not Class
The following warning shall be included in
the instructions for use: This is a Class A product.
In a domestic environment this product may cause
radio interference, in which case the user may be
required to take adequate measures.
ISM equipment suitable for use in domestic
establishments and in establishments directly connected
to a low-voltage power supply network.
ISM equipment suitable for use in all establishments
other than domestic and those directly connected
to a low-voltage power supply network.
The emission limits differ 10 dB between
Class A and Class B equipment, as well as between
the generic emissions standards for the "light"
and "heavy" environments, respectively, when referred
to the same measuring distance. When recalculated
from 10 to 3 meters distance, there is a difference
in radiated emissions of 9.5 dB. It should also
be noted that the classification of computing devices
according to FCC 15, and ISM equipment to FCC 18,
is very similar to that of CISPR 22 and CISPR 11
A product standard is one that covers all
EMC requirements for a certain product type. In
some cases, product standards also cover electrical
safety requirements. A product standard takes preference
over all other standards. Once it is determined
that a product is within the scope of an applicable
product family standard concerning emissions and/or
immunity, then that standard should be followed.
Some examples of family standards include
CISPR 11/EN 55011 Emission standard
for industrial, scientific, and medical (ISM)
radio RF equipment (see Figure 3).
CISPR 12 Emission standard for vehicles,
motorboats, and spark-ignited engine-driven
CISPR 13/EN 55013 Emission standard for
broadcasting equipment like radio, television,
CISPR 14/EN 55014 Emission standard for
household apparatus and portable tools.
CISPR 15/EN 55015 Emission standards
CISPR 20/EN 55020 Immunity standard for
broadcasting equipment, such as radio and television.
CISPR 22/EN 55022 Emission standard for
information technology equipment (ITE).
CISPR 24/EN 55024 Immunity standard series
Newer product family standards also tend
to appear as complementary emissions and immunity
EN 55014-1, EN 55014-2 Emissions
and immunity requirements for household apparatus
and portable tools.
EN 55103-1, EN 55103-2 Emissions and
immunity requirements for professional audio
and video equipment.
Specific types of product family standards
transferred into general standards include:
IEC 555-2/EN 60555-2 LF emissions
standard concerning harmonics for household
IEC 555-3/EN 60555-3 LF emissions standard
concerning flicker and voltage variations
for household products, etc.
IEC 61000-3-2/EN 61000-3-2 General LF
emissions standard concerning harmonics.
IEC 61000-3-3/EN 61000-3-3 General LF
emissions standard concerning flicker and voltage
Today, however, very few pure product standards
exist that cover all requirements. Therefore one
has to look for an applicable product family standard.
An additional complication is that, for the time
being, a product can sometimes belong to different
product family standards. For example, most household
devices must fulfill emissions requirements according
to EN 55014-1, as well as EN 60555-2 and EN 60555-3
or EN 61000-3-2 and EN 61000-3-3.
If no product family standard is applicable,
one must follow the suitable generic or general
standard, which in turn refers to different basic
standards. Some of the product family standards
are also referred to in other standards, which consequently
gives them characteristics of basic standards.
The generic standards include:
EN 55081-1 Emissions standard for residential,
commercial, and light industrial environments.
EN 55081-2 Emissions standard
for industrial environments.
EN 55082-1 Immunity standard for
residential, commercial, and light industrial
EN 55082-2 Immunity standard for
The IEC is also developing corresponding
generic standards, which will be numbered IEC 61000-6-X.
A general EMC standard that covers emissions and
immunity for medical equipment is EN 60601-1-2,
the collateral standard for medical equipment. In
addition to this collateral standard, there are
a number of product standards covering safety and
EMC for specific medical equipment, like EN 60601-2-24,
which covers infusion pumps and controllers.
A general EMC standard that covers emissions
and immunity for TTE equipment is ETS 300 339 (general
standard for radio transmitting equipment). In addition
to this standard, there are a number of ETS/prETS
standards covering EMC for different telecom and
radio transmitting equipment.
As far as the emissions requirements are
concerned, the generic standard is more rigorous
in regard to light industrial environments than
on heavy industry, which as a rule is already rather
electromagnetically contaminated. As far as the
immunity requirements are concerned, the situation
is the opposite. Interference immunity must be hardier
in heavy industrial environments.
What then is applicable in mixed or special
environments? When using the generic standards it
is recommended to begin with the most strict requirements,
which means that the equipment should be classified
according to the "worst" combination, such as EN
50081-1/EN 50082-2. This scenario has sometimes
been used for equipment in hospital environments.
Basic Immunity Standards
The IEC standardization committee for industrial
processing techniques, TC 65, drafted the first
basic standards for immunity to electrical disturbances.
This responsibility has been taken over by the committee
that works with general EMC standards, TC77 (IEC)
and TC 210 (CLC). With this, the publication numbers
changed from IEC 801 to IEC 1000/61000 and EN 61000,
and thus far the disturbance types that have been
dealt with have gone through the following changes:
1. Electrostatic discharges (ESD).
2. Radiated, radio frequency electromagnetic
fields (RF fields).
3. Electrical fast transients/burst
4. Surges (1, 2 µs/50 µs).
5. Immunity to conducted disturbances
radio frequency fields.
6. Immunity to magnetic fields.
IEC 61000-4-8, IEC 61000-4-9,
and IEC 61000-4-10=
EN 61000-4-8, IEC 61000-4-9, and IEC 61000-4-10.
7. Voltage dips, short interruptions,
and voltage variations.
Because some generic standards and some product
standards have been published at the same time as
the aforementioned revised standards, we will have
to live with references to new, as well as old,
basic standard versions for some time.
EMC regulations will be successively refined.
We are going to see a whole series of new standards
and amendments during the next few years. In many
cases new standards will mean increased testing
requirements. And while these testing requirements
might not be welcomed by all manufacturers, they
will benefit the end-users of electrical equipment.
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