RESOURCE PAPER

An EMC Publication
July 2002

An Introduction to Electromagnetic
Compatibility (EMC) Standards
n the design of power systems, To provide guidelines on how to reduce

I engineers have long considered

how to minimize the potential
for causing interference with the
operation of sensitive electronic equipment.
electromagnetic interference, several
professional organizations are working
on EMC standards.
This EPRI Resource Paper was written to
Such interference could occur when electro- increase energy providers' awareness of EMC
magnetic fields or transient events associated with Standards. It is intended to provide an intro-
the operation of the power system interact with duction to EMC standards and related topics
this equipment, overcoming the desired signals that may be of use to power engineers in
and causing system malfunctions. The ability practical matters, such as evaluating and
of electrical or electronic equipment to function dispatching customer complaints, or apply-
satisfactorily in its intended operating environ- ing EMC Standards in the conduct of their
ment without causing electromagnetic disturbances business. The insights derived may be useful
that adversely affect other equipment is known as for understanding the nature and sources of
electromagnetic compatibility (EMC). The recent customer EMC problems and the appro-
proliferation of microprocessors in applications priate testing standards, evaluating vendor
ranging from computers to delicate medical claims or power equipment testing require-
equipment has greatly increased both the ments, or enhancing the installed reliability
incidence and seriousness of EMC problems. of provider or customer equipment.

Table of contents
Background . . . . . . . . . . . . . . . . . . . . . . . .2 Summary . . . . . . . . . . . . . . . . . . . . . . . .10
The Role of Standards in Resolving References and Additional Reading . . . . . .12
EMC Problems . . . . . . . . . . . . . . . . . . . . .2 Appendix A: History of EMC Standards . . .13
The Structure of EMC Standards . . . . . . . . .4 Appendix B: Glossary . . . . . . . . . . . . . . . .14
New EMC Standards . . . . . . . . . . . . . . . . .9
RESOURCE PAPER

· 50/60 Hz Magnetic fields near power

Background facilities have affected certain CRT The Role of Standards in
displays, causing complaints. Resolving EMC Problems
The earliest power system EMC problem · Power line wide-band commu-
was interference with the telephone nications (Internet access) systems Over the years, power companies'
system from magnetic coupling to have caused interference with licensed involvement in the development of
the telephone lines. Later, interference government and amateur radio standards has been through organizations
with AM broadcast receivers from high- communications services. such as the IEEE, ANSI, CISPR and
voltage corona or gap discharges became the IEC. These efforts have yielded
a serious issue. More on EMC history is Many new types of EMC problems standards for the measurement and
given in Appendix A. Today, attention are not well understood and effective limitation of radio noise and on the
has shifted to interference involving methods to mitigate them have not yet susceptibility of microprocessor-based
hand-held radios, power lines located been developed. In the process of resolv- relays to RF fields. Already these efforts
along railroad rights of way, and ing these issues, it is important to under- have played a large role in mitigating
potentially sensitive electronic stand existing EMC standards that may power transmission EMC problems.
systems.The original EMC problems be relevant and their application to real In parallel with these efforts, numer-
were "mitigated" using methods such problems. Standards provide guidance in ous other industry-specific EMC stan-
as reconfiguring the architecture of the implementing uniform testing techniques dards have been developed. Originally,
telephone system to minimize magnetic for controlling EMI and ensuring com- standards were written by and for the
coupling, reducing corona discharges on patibility of control equipment used military and their contractors. They
high voltage transmission lines and re- in the generation and transmission of were interested, for example, in the
pairing gap discharges on distribution electric energy. compatibility of radios and vehicles or
lines to minimize electromagnetic Also contributing to new EMC radar systems and sensitive receivers. In
interference (EMI). In the process problems is the changing electro- more recent years, however, the use of
of mitigating them, however, it was magnetic environment of the power European EMC standards for conformity
recognized that the development of system. Higher voltage transmission, for testing of commercial products has in-
industry wide standards for measure- example, has resulted in more corona and creased dramatically. The European
ment and design would be of great higher currents on transmission and Union (CE mark) requirements have
benefit. New problems have emerged distribution lines have caused higher driven the implementation of EMC
and are bringing the issue of EMC to magnetic fields. In addition, maintenance standards requiring immunity
the attention of Energy companies once and staffing reductions have contributed (interference tolerance) testing for
more. Consider some of these real-world to more difficulty with locating and commercial products bound for Europe.
EMC problems: repairing arcing sources on the
· Hand-held radios used by power distribution lines. The use of power Energy Provider EMC Issues
personnel have interfered with the electronic devices has resulted in more Energy provider EMC problems are
operation of microprocessor relays intense electromagnetic fields at higher mainly related to two issues: First, the
and caused malfunction of frequencies. Also, proposed wide-band electromagnetic emissions caused by
distribution circuit breakers. power line communications systems may operation of the power system that might
· Electromagnetic fields from power generate additional high frequency cause "harmful interference," and second
lines located along railroad easements electromagnetic fields. the immunity of power control and
have caused malfunction of railroad Power companies should thus be communications equipment to the
signaling systems. concerned about EMC standards because electromagnetic disturbances from
· Electromagnetic fields from spark they will help resolve EMC problems the environment in which it operates.
discharges on distribution lines near in their generating plants and power Standards and other reference documents
airports have interrupted commu- delivery facilities. Standards will also that apply to both types of issues have
nication between the control tower help ensure that equipment made been written and are discussed here.
and airplanes on landing approaches. available by vendors meets industry
· Electromagnetic fields from currents EMC requirements. Power Frequency Emissions
injected into the power system by The operations of generating and
power electronic controllers, known distributing electric energy produce
collectively as Flexible AC Trans- electric and magnetic fields that may
mission System (FACTS) devices, interfere with the normal functioning
have caused false blocking signals on of provider or customer equipment.
relay communication systems using a They may disrupt systems such as
power line carrier (PLC). cathode ray tube (CRT) computer
monitors, photolithography systems

2 An Introduction to Electromagnetic Compatibility (EMC) Standards

 RESOURCE PAPER

or electron microscopes. These power found in CIGRE 36.04 and IEC 61000- notification by a Commission
frequency fields may also cause mal- 6-5. (5) (6) Table 5 shows the transient representative that the device is causing
function of railroad signaling systems. immunity tests that ensure functional harmful interference. Operation shall not
Railway EMC concerns are covered in reliability of energy production and resume until the condition causing the
the European Standard series EN 50121 distribution equipment by testing to harmful interference has been corrected."
and the "Blue Book" of the American immunity types and levels of suscepti- This standard normally applies to
Railway Engineering and Maintenance- bility from realistic simulations of the power line emissions from incidental
of-Way Association (AREMA) (1)(2). hostile power environments. sources, such as corona or gap discharges.
These references are useful for In the case of corona, transmission lines
designing power lines to be Radio Frequency Emissions are designed to reduce the associated
compatible with railroad signaling The power system may also generate noise to acceptable levels. Gap discharges
and communication operations. radio frequency interference (RFI), which usually occur in aging systems and are
can interfere with the operation of com- addressed by preventative maintenance
Harmonic Frequency Emissions munication and navigation systems, and mitigation of the arcing problems
Nonlinear loads may cause voltages and long or medium wave radio and as they occur. Standards for this type
currents and their resultant electric and television broadcast, aeronautical of interference are usually related to line
magnetic fields to occur at low-order beacons, amateur radio and aircraft design and measurement issues rather
harmonic frequencies. These currents communication. Table 4 shows standards than the setting of limits, such as IEEE-
are well known sources of transformer for common power system emitters, 430 (1992) and CISPR 18-2 (1996-12).
damage and their associated fields can including corona from HV transmission (8)(9) A major exception to this is the
couple into interference receptors such lines, "tracking" or "scintillation" across Canadian Standard CAN3-C108.3.1-
as analog telephone systems. the surface of contaminated string M84, which sets limits for RFI from
The management of harmonic insulators, and gap discharges (arcing) corona at the edge of the right-of-way.
frequency currents and their fields is from imperfections in the LV distribu- (10)
one aspect of "power quality" (PQ). tion hardware. Other emitters include When the power system is used as a
Although power quality is not EMC, HVDC converters, VAR compensation "carrier current" for communications,
the two topics are related. Power quality equipment or FACTS devices—which 47CFR15 defines the power line as an
is generally restricted to outages and low may produce RFI up to a few MHz— "unintentional radiator" and provides
frequency disturbances (< 9 kHz) that power line carrier (PLC) systems, and specific limits on emissions. In addition,
are conducted to equipment through the recently proposed systems for providing there are several European national
electricity lines. EMC is considered to be consumer broadband services via standards, of which the UK Draft MPT
wider bandwidth disturbances that reach power lines. 1570 standard, "Radiation Limits and
"victim" equipment through electric and Measurement Standard," is one example.
magnetic field coupling. These coupling Legal Implications (11) The limits contained in these stan-
paths may also relate to safety concerns Normally operating power systems are dards could present severe constraints on
due to grounding systems. In the US, the defined as "incidental radiators," in Part the operation of wide-band power line
quality of power is monitored in accor- 15 of the US government telecommuni- communication systems.
dance with IEEE-1159-1995. (3) In cations regulations (47CFR15). (Power
Europe, EN 50160-1999 addresses the systems do not radiate RF energy as an Other Emissions
important characteristics of the voltage at intended aspect of power system oper- Energy provider-owned microwave
the customer's terminals in public low- ation, but rather "incidentally" as a by- systems and hand-held radios and non-
voltage (LV) and medium-voltage (MV) product of their operation.) (7) As a power communications systems mounted
distribution systems. (4) result, "harmful interference" as defined on leased tower space must be considered
in 47CFR15 must be avoided. The as sources of EMI because they are often
Transient Emissions & Immunity Federal Communications Commission used near sensitive provider-owned
Transient currents and fields are caused (FCC) defines such harmful interference control and communication systems.
by distribution switching operations or as "any emission, radiation, or induction (The standards that apply to these
lightning induced effects. These events that endangers the functioning of a radio devices relate to human exposure
may interfere with the operation of navigation service or of other safety limits and are not discussed here.)
distribution equipment and are the services or seriously degrades, obstructs Although unintended, transmission
subject of several EMC Standards. or repeatedly interrupts a radiocommuni- towers and overhead grounding systems
There are no regulated limits on the cations service operating in accordance may also act as "parasitic" sources that
transient electromagnetic fields or vol- with this chapter." According to the reradiate other signals. This effect can
tages in power plants and substations. Commission, "The operator of a radio cause the radiation patterns of AM
However, guidance on acceptable frequency device shall be required to broadcast antennas to be modified
equipment immunity levels can be cease operating the device upon (12) and can degrade signals from the

An Introduction to Electromagnetic Compatibility (EMC) Standards 3

RESOURCE PAPER

nationwide differential global positioning the emission and immunity standards, In Europe, the EMC Directive
system (NDGPS) network. with the overall objective of achieving (89/336EEC) addressed all products
electromagnetic compatibility." (4) that may cause emissions or whose
Immunity in the Power performance may be affected by electro-
Systems Environment magnetic interference. The "Essential
Energy companies often depend upon Requirements" of the Directive were that
equipment that may not be immune to The Structure of products not disturb radio, telecommuni-
the electric and magnetic environment EMC Standards cations, or other products (emissions
generated by the power system itself. limits) and that they have adequate
Examples include CRT monitors and EMC Standards are structured around levels of intrinsic immunity to
magnetic fields (covered in EN55024), prescribed tests for conducted (e.g. interference to operate as intended
(13) distribution relays and susceptibility through wires) and radiated (through (immunity requirements). The Directive
to RF fields from hand held radios space) effects. What comes out of a also requires the application of the "CE
(covered in ANSI C37.90), (14) or product is measured by emissions tests. Mark" for all consumer, commercial,
control instrumentation in substations What is imposed onto a product is industrial, scientific, or medical
that may be susceptible to the operation referred to as immunity, or susceptibility, electronic products—virtually all
of contactors or circuit breakers. The testing. The four quadrants shown in electrical and electronic products
immunity standards that apply to such Table 1 represent the four major types or installations (Figure 1).
equipment are shown in Table 5. It is of EMC tests: The presence of this Mark is a legal
important that equipment acquired for 1. Conducted Emissions (samples RF statement indicating that the product
use in these environments be tested noise voltages "kicked-back" into the meets the Essential Requirements of
for immunity to the typical inter- power lines) the Directive and that "harmonized"
ference threats found in the 2. Radiated Emissions (uses antennas to standards were used to assess the pro-
substation environment. measure RF "leakage" & re-radiation duct for conformity to emissions and
In Europe, an EMC Directive from wires) immunity (susceptibility) requirements.
addressing electromagnetic compatibility 3. Conducted Immunity (imposes (In other words, it was tested in all four
between the power emissions sources and interference into wires) quadrants of Table 1.) Full EMC com-
the customers' equipment (89/336EEC) 4. Radiated Immunity (radiates patibility is more likely to be assured,
was enacted in 1992. The "harmonized" electromagnetic waves onto however, by the addition of related
standard for power quality used through- the product) immunity tests, because customers often
out Europe (EN50160) states: "It should regard "reliability" as the most important
be noted that this question is addressed These types of tests are performed feature of a product and identify a pro-
directly by other standards, already using EMC Standards to guide the test duct that is more "immune" from inter-
published or in preparation: Emission engineers. In the US, the concept of ference as a more reliable product.
standards govern the levels of electro- "harmful interference" applies, and The E.U. standards structure is thus
magnetic disturbances which customers' conducted emissions and radiated based on a hierarchy of Basic, Generic,
equipment may be allowed to generate. emissions testing (against CISPR limits) and Product Standards, as shown in
Immunity standards set down distur- on typical electronics is required, which Figure 2:
bance levels that the equipment should limits the amount of EMI emitting from 1. Basic Standards describe the
be capable of tolerating without undue these items. Products must withstand phenomena we're trying to simulate,
damage or loss of function. A third interference and operate safely, and like the damaging effects of ESD or
set of standards, for electromagnetic must not cause harmful interference lightning, or how to measure radio
compatibility levels, has the function of (items 1&2 above). (7) emissions coming from products.
enabling coordination and coherence of

Table 1
Types of EMC Tests Basic Standards

Emissions Immunity Generic

Standards
Conducted 1 3 Product
Standards
Radiated 2 4 Figure 2. European Standards
Figure 1. CE Mark Structure

4 An Introduction to Electromagnetic Compatibility (EMC) Standards

 RESOURCE PAPER

2. Generic Standards describe the genre and compared to limits such as that immunity was mandated from 26–
(location) where the product will be shown in Figure 4. 500 MHz without modulation at field
used, such as consumer or commercial Immunity standards attempt to ensure strengths as high as 10 V/m at 3 meters
versus heavy industrial settings. EMC compatibility between a product distance. This Standard has now been
3. Product Standards describe the and the environment in which it is used. changed to 80–1000 MHz with AM
mixture of emissions and immunity The Generic Standards of the 1990s modulation and cell-phone (pulsed)
tests to be applied to a particular required immunity testing for radiated modulation to more accurately simulate
product type, often industry-specific. and transient immunities. Radiated modern RF environments. (19)(13)

When the EMC Directive was

published in 1992, many product
standards had not yet been written, Table 2
and the affected manufacturers used EMC Standards Matrix
the generic standards for guidance in
the application of tests. The generic Type of Disturbance Emissions Immunity
standards simply covered emissions
& immunity testing in light industrial Conducted RF (wires) MIL, US, EU MIL, EU
and heavy industrial product
locations (genres). Radiated RF (air) MIL, US, EU MIL, EU
As product standards were written, Power-line related EU, Harmonics EU, Magnetic fields
they focused on six major product areas: EU, Flicker EU, Dips & interrupts
1. Industrial, scientific, & medical Electrostatic Discharge EU
(ISM) products (15)
2. Industrial process, measurement, Electrical Fast Transient EU
& control (IPM&C) products (16) Surge EU
3. Broadcast receivers &
consumer electronics Additional Standards Required After 2001
4. Tools & appliances
5. Lighting equipment
6. Information technology equipment
(ITE), such as computers and
EN 61326-1 CONDUCTED EMISSION LIMITS FOR CLASS A EQUIPMENT
telephone products (17)
CLASS A quasi peak CLASS A average

Table 2 provides details on MIL, US 90

and EU Standards used to assess these

types of products.
80
Emissions testing for these products
tries to limit the amount of EMI (inter-
ference or radio leakage) radiated into 70
the environment. The Generic Standards
EMISSION LIMIT (dBµV)

of the 1990s required that a product be

60
tested for conducted & radiated
emissions related to CISPR limits.
(15)(17) Conducted emissions testing 50
imposes limits for the amount of voltage
a product may inject back into its power
40
lines, which can cause re-radiation from
those lines or other harmful effects. Con-
ducted emissions limits for IPM&C 30
products (16) are shown in Figure 3
for Class A (industrial) products. To
compare actual product performance 20
0.1 1 10
to the EMI limits, radiated emissions FREQUENCY (MHz)
are measured on an open area test site
(OATS) or suitable anechoic chamber Figure 3. Limits for Conducted Emissions

An Introduction to Electromagnetic Compatibility (EMC) Standards 5

RESOURCE PAPER

Since this test required intentionally (ESD) and electrical fast transient (EFT), voltages up to 8 kV, and air discharges to
transmitting RF energy, it was necessary was also required. (18) (20) 15 kV,as shown in Figure 6. The IEC
to conduct such radiated immunity ESD testing required an appropriate 61000–4-2 Standard (18) requires the
testing within a shielded fully anechoic simulator (ESD "gun") with plate use of this "contact mode" method to
chamber, without outside radio leakage antenna and accessories for floor ensure repeatable testing results on metal
or internal reflections, as shown in standing or table top products. Newer encased products.
Figure 5. Testing for transient immunity, versions of this standard require the EFT (or burst) testing simulates the
in the form of electrostatic discharge direct injection of sub-nanosecond rush of arcs that repeatedly form and
extinguish when a magnetic field col-
lapses across the opening contacts of a
switch. This "showering arc" or "burst"
EN 61326-1 EMISSION LIMITS FOR CLASS A EQUIPMENT of short rise-time, short duration pulses
dBµV/m quasi peak at 10 m dBµV/m quasi peak at 30 m
is problematic for products using micro-
70
processors. In poorly decoupled pro-
ducts, the noise pulses are mistaken for
60
data or timing information, and product
latch-up is a common result. The immu-
50
nity standard requires common-mode
testing on power and I/O lines, at
EMISSION LIMIT (dBµV/m)

40
repetition rates from 2.5–5.0 kHz.
Many nondestructive field failures can
30
be simulated in the laboratory by using
higher repetition rates, (20) and the
20
Guide on EMC in Power Plants and
Substations prepared by the CIGRE
10
Working Group 36.04 in 1997 calls out
various repetition rates up to 1 MHz. (5)
0
10 100 10
Compliance & Enforcement
FREQUENCY (MHz) Compliance with the CE Marking
requirements for intentional radiators—
Figure 4. Limits for Radiated Emissions those products that intentionally transmit
RF energy when being used—mandates
the Type Acceptance Route to market.
This route imposes testing by a recog-
nized or accredited laboratory and/or
submission of product samples to the
appropriate national authorities. For
unintentional radiators—those products
that may accidentally emit RF energy
(the vast majority of consumer and
commercial items)—there are two
routes to conformity with the essential
requirements of the EMC Directive.
1. Standards Route – for simple
products that will pass all the
"harmonized" tests in their
product standard
2. Technical Construction File –
for products where :
· There is no harmonized
European EMC Standard;
· Standards exist, but can only
be applied in part;
Figure 5. Fully-Anechoic Chamber

6 An Introduction to Electromagnetic Compatibility (EMC) Standards

 RESOURCE PAPER

· Testing to harmonized Standards Some of these test laboratories have instruments illustrate the recent
is not practical, due to size, mutual recognition agreements with regulatory burden for manufacturers
location, etc.; accrediting firms in other jurisdictions. of industrial process, measurement, and
· A large number of product Many of these testing bodies also offer control (IPM&C) instruments bound for
variations makes testing each private labels, or "marks," which reflect Europe in the 1990s. (16) This classifi-
combination impossible; the levels of testing undertaken. While cation would include such common
· Other recognized EMC Standards not replacing the CE Mark or its legal items as portable oscilloscopes, hand-held
were used, such as MIL-STD, etc. responsibilities, these "marks" could DVM's, and common panel meters used
indicate the testing types, levels, and in power control settings. The testing
Enforcement of the E. U. Directive performance criteria to which the burdens for these types of instruments
rests with each national authority. In the product was subjected. are shown in Table 2. Conducted
UK, for example, the trading standards emissions and radiated emissions are
departments of the local authorities can Product Examples required in the US and Europe and in
levy civil penalties of three months Three common power-measuring some smaller markets as well. Products
and/or £5,000, or both. Competitors
typically provide good leads on where
violations are occurring. In the US, trade
show exhibits are scanned by the FCC Table 3
to detect "harmful interference," and Performance Criteria During Immunity Testing
products are also acquired and tested
by the Commission. In both markets, Type A EUT performs normally during the test.
complaints drive the enforcement
process, with authorities launching an Type B EUT performs normally after the test, without loss of stored
investigation after a complaint from a data or change in operational mode. Performance degradation is
user or a competitor comes in. The data allowed during the test.
in Europe are archived by the manufac-
turer's representative or legal agent. In Type C A & B apply, but normal performance after the test requires
the US, the data are required to be on operator intervention.
file with the manufacturer. In either case,
only a national authority can compel the Type D Non-recovering failure (damage).
delivery of the test data. In most cases, a
manufacturer issues a "Declaration of
Conformity" stating which standards
were used to test the product and to
establish compliance with the essential
requirements of the EMC Directive in
Europe, or with due diligence and good
manufacturing practice for self-
declaration in the US.
Large manufacturers typically utilize
their own in-house EMC Qualification
testing facilities, and smaller firms often
use third-party test houses for assessing
conformity. In either case, many
manufacturers will attempt some
"pre-qualification" testing at their plants
to quantify their EMC concerns and
evaluate the effectiveness of any mod-
ifications. Often, such equipment is low-
cost and non-compliant, but still useful.
Some firms use a non-conforming test
site—such as their laboratory test floor—
and clever engineers can implement non-
standard uses for immunity test equip-
Figure 6. Table-top ESD Testing
ment to expose design weaknesses.

An Introduction to Electromagnetic Compatibility (EMC) Standards 7

RESOURCE PAPER

Table 4 bound for Europe (CE-marked) and

EMC Emissions Standards many other high-quality products are
subjected to immunity testing as well.
Equipment purchased by energy
EN55011(1991) Emissions from Industrial, Scientific, &
companies is often sold in Europe and
Medical equipment
tested according to the product standard
EN55013(1998) Emissions from Broadcast Receivers for the IPM&C equipment (IEC 61326-
1). However, energy providers have also
EN55013(1998) Emissions from Broadcast Receivers
recognized that these requirements may
EN55014(1993) Emissions from household appliances and tools not be sufficient to guarantee immunity
in the power station and substation
EN55015+A2(1999) Emissions from lighting equipment
environments, which are both different
CISPR 18-2(1996) Emissions from overhead power lines & HV equipment and more severe. For this reason, IEC
Standard 61000-6-5 has been developed
EN55022(1998) Emissions from Information
to specify additional tests that more
Technology Equipment
closely mimic the power station and
IEEE 430(1992) Emissions from overhead power lines & substations substation environment (the Basic
Standards within IEC 61000-6-5 are
MIL-STD-461E Radiated & Conducted Emissions from U.S.
shown in bold in Table 5). All Immunity
military products
testing is carried out while monitoring
FCC (47CFR15) Emissions from U.S. commercial electronics the performance of the equipment under
test (EUT.) In order to fully specify an
EN61000-3-2(1995) Conducted harmonic emissions from products
immunity test and get consistent results,
drawing up to16AMPS
it is necessary to quantify the EUT
EN61000-3-3(1995) Voltage fluctuations (flicker) emissions from performance criteria during immunity
products up to 16AMPS testing. The European Immunity
Standards use the definitions in Table 3.
Only CE-marked products or those
designed to meet the highest standards
are generally tested for immunity at all,
and this testing is not required for many
markets, such as consumer products in
the US or Asia. The question thus arises,
Is such "commercial grade" equipment
good enough for power system environ-
ments? Probably not. In practical terms,
only products that are CE-Marked
should be considered for heavy industrial
or professional use, because the cost of
down time is just too great. For this
reason, many manufacturers voluntarily
test their products for immunity, even if
they are not shipping them to Europe.
A practical approach to ensuring
compatibility and reliability at power
plants and transmission substations
levels is provided by the Guide on
EMC in Power Plants and Substations
prepared by the CIGRE Working Group
36.04 in 1997. (5) Aspects of this
approach include:
· Characterize worst-case
disturbances, then choose
reasonable immunity levels;
Figure 7. Level-setting Procedure
· Ensure that no level of distur-

8 An Introduction to Electromagnetic Compatibility (EMC) Standards

 RESOURCE PAPER

bance above the threshold level are usually applied with Coupler IEC 61000-4-8 (2001) uses induction
can arise; Decoupler Networks (CDN's) for coils to produce a 50-60 Hz H-field
· Specify acceptance criteria for most common lines, and the level of that is brought near a product or into
each function of automation interference is established with a level- which a product is placed. (23)
and control systems; setting procedure shown in Figure 7. 4. Power Dips & Interrupts–Some
· Specify the equipment and (22) products are more sensitive than
installation practices to provide 3. Power line Magnetic Fields–With others are to momentary interrup-
the immunity levels required; increasing reliance on computers and tions or longer perturbations on
· Specify the tests to verify that these telecommunications equipment, their their power inputs. IEC 61000-4-11
goals have been achieved resistance to power line magnetic (2001) simulates both rapid, short
fields is essential when they are sub-cycle dips and the longer, slower
The CIGRE survey of standardized installed near power distribution interruptions seen in motor intensive
procedures used to carry out the tests equipment or other magnetic sources. locations. (26)
is based on IEC 1000-4-x series of
immunity tests. The EMC Standards Table 5
cited by the CIGRE Guide on EMC EMC Immunity Standards
in Power Plants and Substations are
highlighted in Table 4 (Emissions) and
Table 5 (Immunity.) In Europe, these EN50082-1(1997) Generic immunity; residential, commercial, & light
standards are also cited in IEC 61000-6- industrial locations
5, Immunity for power station and EN55014-2(1997) Immunity of household appliances and tools
substation environments. (6)
EN55020(1994) Immunity of broadcast receivers
EN55024(1998) Immunity of Information Technology Equipment
MIL-STD-461E Radiated & Conducted Immunity for U.S. military
"New" EMC Standards products
IEC61000-4-2(1999) Immunity to electrostatic discharge
For CE Marking in 2001, six new stan-
dards were added to those previously IEC61000-4-3(1998) Immunity to radiated RF electromagnetic fields
discussed—four immunity standards IEC61000-4-4(1995) Immunity to electrical fast transient (burst)
and two emissions standards, shown
highlighted in Table 2. These standards IEC61000-4-5(1995) Immunity to indirect lightning strike (surge)
include: IEC61000-4-6(1996) Immunity to conducted disturbances from RF
1. Surge–Modern buildings often feature fields
lightning rods for the dissipation of
energy from "direct" lightning strikes, IEC61000-4-8(2001) Immunity to power frequency magnetic fields
but the electromagnetic effects of IEC61000-4-9(2001) Immunity to pulsed magnetic fields
these events are destructive to wire-
connected products within about IEC61000-4-10(2001) Immunity to damped oscillatory magnetic fields
five miles. To simulate the damage IEC61000-4-11(2001) Immunity to voltage dips & fluctuations on
inflicted by these "indirect" strikes, AC mains
IEC 61000-4-5(1995) describes
methods, waveforms and energy levels IEC61000-4-12(2000) Immunity to oscillatory waves
for testing power, I/O and telecoms IEC61000-4-13(Ed. 1) Immunity to harmonics & inter-harmonics at
lines. (21) AC power ports
2. Conducted RF Voltages–With the
increasing density of RF emitters, the IEC61000-4-16(1998) Immunity to conducted disturbances from 0-
ability of cabling bundles to withstand 150 kHz
immersion in RF fields from inten- IEC61000-4-17(1999) Immunity to ripple on DC power inputs
tional transmitters is crucial. IEC
61000-4-6(1996) details test equip- IEC61000-4-27(2000) Immunity to phase imbalance
ment and methods for simulating IEC61000-4-28(1999) Immunity to power frequency variations
the effects of external transmitters
inducing modulated RF voltages IEC61000-4-29(2000) Immunity to voltage dips & fluctuation on DC mains
onto power and I/O lines. Voltages

An Introduction to Electromagnetic Compatibility (EMC) Standards 9

RESOURCE PAPER

5. Power line Harmonic Emissions– 61000-4-12(1995) requires 100 kHz the "product" they produce, but these
Switched-mode power supplies and 1 MHz damped oscillatory standards are only an indication that the
commonly used in modern computer waveforms (27) source, transmission medium, and load
equipment draw short pulses of 4. Harmonics, Interharmonics, & Mains are compatible with each other. Under-
current at the tips of the applied Signaling–IEC 61000-4-13 (2001 Ed. standing EMC standards helps utility
line voltage. This non-sinusoidal 1) specifies testing for the immunity personnel build and maintain reliable
current is rich in harmonics of the or "tolerance" of products to power installations that produce good quality
fundamental line frequency, and these frequency harmonics, interharmonics, output, and helps them in their inter-
high-order currents can be harmful in and mains signaling (PLC) actions with customers. (35)
power distribution networks. This interference. (28) Supplier- and consumer-side EMC
"emission" is addressed in EN 61000- 5. Conducted disturbances from 0–150 characterization and testing is important,
3-2 (1995), which establishes test kHz–IEC 61000-4-16(1998) indicates since they assure compatibility between
methods and limits for these har- methods and limits for simulating the equipment of producers and con-
monic currents for single-phase pro- conducted disturbances in the sumers of electric energy. Currently,
ducts drawing 16 AMPS or less. (33) frequency range of DC to 150 kHz immunity testing is only required in
6. Power line Flicker Emissions– on power lines. (29) Europe, but that is changing. Already,
Variations in the current demand of 6. Unbalance, immunity test–IEC in the power, military and medical
electrical and electronic products can 61000-4-27(2000) supplies infor- industries in the US, the push is on to
cause the line voltage to sag, and if mation on the testing of products implement a variety of immunity tests
these demands are recurring, the lights for tolerance to unbalanced condi- to ensure reliability and minimize risk.
can "flicker" or vary in brightness. tions on the power mains. (30) Providers tasked with building or
This annoyance is more dangerous at 7. Variation of power frequency–IEC modifying generation or substation
frequencies and intensities that can 61000-4-28(1999) specifies test facilities are using CIGRE 36.04 and
precipitate seizures in some suscep- conditions and performance criteria IEC 61000-6-5 to guide them in
tible individuals. These variations in for "power tolerance" testing of pro- specifying and testing products that
brightness, and their cause, variations ducts subjected to variations in the contribute to the installed reliability
in load, are addressed in EN 61000-3- power frequency. (31) of the facility, not detract from it.
3 (1995) using a stable laboratory AC 8. Voltage dips, interruptions, & These standards are based on the
supply, reference impedance and a variations on DC power–IEC 61000- "Basic Standards" of the European
"flickermeter." (34) 4-29(2000) gives test conditions and Union, the most widely used and
criteria for evaluating equipment sub- respected EMC standards currently in
More "power tolerance" tests are
jected to assorted variations on the circulation, and test equipment is widely
slated for implementation in the future.
DC input power mains (32) available for them. (5) (6)
Typically, a few years pass between
Providers also want to offer customers
groups of new standards, and two groups
the best quality product possible, and
have been implemented from 1992-2001
power quality standards are used to
in Europe. The first group was mandated
measure it. Providers can also help
in 1995, and the second group in 2001.
customers tolerate certain amounts of
Some of the new standards awaiting
Summary imperfection in the power delivered to
"harmonization" by CENELEC include:
them, as measured by new "Power
1. Pulsed magnetic field immunity–
With the increasing speed and Tolerance" tests. In fact, both power
IEC 61000-4-9(2001) uses the same
proliferation of sensitive electronics, quality and power tolerance testing is
induction coils as IEC 61000-4-8
coupled with ever more low-power required to ensure (EMC) between
to expose the product to pulsed (uni-
wireless applications, the problems providers and their customers.
polar) magnetic fields by connecting
associated with EMC will only get
the Combination Wave surge gener-
worse unless appropriate standards
ator used in IEC 61000-4-(1995) to
are provided. Understanding the EMC
the induction coil. (24)
Standards used to evaluate products
2. Damped oscillatory magnetic field
for "reliability" helps power personnel
immunity–IEC 61000-4-10(2001)
choose equipment for their facilities that
uses a 100 kHz period "ring wave"
will ensure compatibility, and helps them
generator driving the induction coil
assist customers in procuring equipment
to produce changing polarities of
that is tolerant to outside interference.
magnetic fields. These can result
Service providers use power quality
from power switching operations. (25)
standards to measure the quality of
3. Oscillatory wave immunity–IEC

10 An Introduction to Electromagnetic Compatibility (EMC) Standards

 RESOURCE PAPER

EMC Standards Organizations

North American EMC standards are published by the FCC–The Federal Communications Commission is an inde-
American National Standards Institute (ANSI), the Institute pendent agency of the US Federal Government and is directly
of Electrical and Electronics Engineers (IEEE), the Federal responsible to Congress. The FCC was established by the
Communications Commission (FCC), and the Canadian Communications Act of 1934 and is charged with regulating
Standards Association (CSA). European EMC standards interstate and international communications by radio, televi-
are developed for CENELEC (the European Committee for sion, wire, satellite, and cable. The FCC also allocates bands of
Electrotechnical Standardization) and are harmonized across frequencies for non-government communications services (the
Europe based on existing IEC and/or CISPR standards. There NTIA allocates government frequencies). The general EMC
are similarities between international and US standards. requirements in the US are set by the FCC. The Code of
Emissions tests are required by both. Immunity tests are Federal Regulations (CFR) Title 47, Part 15 covers radio fre-
required in Europe and used for high-reliability applications in quency devices capable of emitting RF energy in the range of
the US. 9 kHz to 200 GHz. Testing should be done in accordance
with ANSI C63 standards.
ANSI–The American National Standards Institute administers
and coordinates the U.S. voluntary standardization and confor- IEC–The International Electrotechnical Commission (IEC),
mity assessment system. ANSI was founded in 1918 by five largely through its CISPR committee (established in 1934)
engineering societies and three government agencies and func- generates EMC standards that address emissions, and through
tions as a private non-profit membership organization. The TC-77 (established in 1973) addresses immunity requirements
primary ANSI standards for EMC are contained in the C63 and test procedures. The IEC works closely with CENELEC
series of standards. and the International Organization for Standardization (ISO).
CSA–The Canadian Standards Association is a non-profit, ITU–The International Telecommunications Union is
private, member-based association that develops standards. responsible for international frequency allocations and
The CSA does recognize certain standards promulgated by radio frequency spectrum management.
other organizations. These "endorsed standards" are non-
Canadian standards that have been reviewed by CSA and IEEE–The Institute of Electrical and Electronics Engineers
are approved for use in Canada. was founded in 1884 and is the world's largest technical
professional society. IEEE promulgates standards that apply
CENELEC–The European Committee for Electrotechnical to many subjects, including EMC topics in cooperation
Standardization (Comite Europeen de Normalisation Electro- with ANSI.
technique) was established in 1973 as a non-profit organiza-
tion. CENELEC has been mandated by the European ISO–The International Organization for Standardization is a
Commission (EC) to adopt (harmonize) the standards neces- worldwide federation of national standards bodies from about
sary to show conformity with the Essential Requirements of 140 countries. ISO is a non-governmental organization estab-
the EMC Directive. CENELEC has the responsibility for pro- lished in 1947 to promote the development of standardization
ducing harmonized European EMC standards and adopts and related activities. The work of ISO results in international
proposed IEC standards as written or rejects them for a new agreements that are published as International Standards.
EN standard. CENELEC Technical Committee TC210 is MIL-STD–US Military Standards are prepared by EMC
responsible for EMC standards (previously this was TC110). personnel of the US Army, Navy, and Air force. The EMC
According to a 1991 agreement, the IEC has primary responsi- requirements of the military are different from commercial
bility for the development of standards. When CENELEC needs and the Tri-Service EMC Committee revises and up-
identifies the need for an EMC standard, it asks the IEC to dates EMC standards as necessary. Military standards are gen-
develop it. If the IEC is not in a position to carry out the erally more elaborate and tend to be more stringent than their
requirements, CENELEC will perform the work itself. non-military commercial or civilian counterparts. The primary
CISPR–The International Special Committee on Radio military EMC standard is MIL-STD 461E, which covers
Interference (Comite International Special Des Pertubations EMC methods and limits. The basic concepts of MIL-STD-
Radioelectriques) was set up in 1934 with the object of reach- 461 have been adopted by several non-US military organiza-
ing worldwide agreement on control of radio interference and tions and also influence national and international
thus avoiding barriers to trade. CISPR covers the frequency standardization efforts.
range from 9 kHz to 400 GHz. It is a special committee of NTIA–The National Telecommunications and Information
the International Electrotechnical Commission (IEC) differing Administration is an agency of the US Department of Com-
from IEC's normal technical committees in that it has a wider merce. The NTIA manages the Federal Government's use of
membership. Technical committees are made up of national the radio frequency spectrum and allocates government fre-
representatives from IEC member countries. quencies (the FCC allocates non-government frequencies).
ETSI–The European Telecommunications Standards Official Journal of the European Communities–The
Institute is a non-profit organization established to produce OJEC is published every day in all eleven official languages of
telecommunications standards concerning telecom and radio the European Union (EU), containing material on legislation,
transmitting equipment. information, and notices. An EMC standard is deemed to be
"harmonized" once it has been published in the OJEC.

An Introduction to Electromagnetic Compatibility (EMC) Standards 11

RESOURCE PAPER

(9) IEC / CISPR 18-2, Radio interfer- (18) IEC 61000-4-2 (1999-05): Electro-
References and additional ence characteristics of overhead power magnetic Compatibility (EMC) - Part 2:
reading lines and high voltage equipment, Testing and measurement techniques–
Amendment 2. 1996-12 Electrostatic discharge immunity test 1st
(1) ENV50121-1: 1999 Railway applica- ed. Geneva, International Electrotech-
tions–Electromagnetic Compatibility - (10) CAN3-C108.3.1-M84, 1984 nical Commission, 1999
Part 1 - General, The European Limits and Measurement Methods of
Committee for Electrotechnical Electromagnetic Noise from AC Power (19) IEC 61000-4-3 (1998-11):
Standardization, 1st ed. Brussels, Systems, 0.15 - 30 MHz, Canadian Electromagnetic Compatibility (EMC)–
CENELEC 1999 Standards Association, Ontario, Canada Part 4-3: Testing and measurement
techniques - Radiated, radio-frequency,
(2) "Principles and Practices for induc- (11) Draft MPT 1570, Radiation electromagnetic field immunity test 1st
tive coordination of electric supply and Limits and Measurement Standard, ed. Geneva, International Electrotech-
railroad communication/signaling sys- Radiocommunications Agency, London, nical Commission, 1998
tems," Association of American Rail- February 2000
roads and Edison Electric Institute, Joint (20) IEC 61000-4-4 (1995-01):
Committee on Inductive Coordination, (12) IEEE Standard 1260, "Guide on Electromagnetic Compatibility (EMC)–
Washington DC and New York, 1977 the Prediction, Measurement and Anal- Part 4: Testing and measurement
ysis of AM Broadcast Reradiation by techniques–Section 4: Electrical fast
(3) IEEE Std 1159-1995 IEEE Power Lines." 1996 transient/burst immunity test 1st ed.
Recommended Practice for Monitoring Geneva, International Electrotechnical
Electric Power Quality, Institute of (13) EN55024:1998 Electromagnetic Commission, 1995
Electrical and Electronics Engineers, Compatibility (EMC) - Immunity of
Inc., 345 East 47th Street, New York Information Technology Equipment (21) IEC 61000-4-5 (1995-02):
(ITE) The European Committee for Electromagnetic Compatibility (EMC)–
(4) EN50160:1999 Voltage Charac- Electrotechnical Standardization, 1st ed. Part 4: Testing and measurement tech-
teristics of electricity supplied by Brussels, CENELEC 1998 niques - Section 5: Surge immunity test
public distribution systems, 1st ed. 1st ed. Geneva, International Electro-
Geneva, IEC, 1999 (14) IEEE Std C37.90.2-1995 IEEE technical Commission, 1995
Standard for Withstand Capability
(5) Guide on EMC in Power Plants of Relay Systems to Radiated Electro- (22) IEC 61000-4-6 (1996-04):
and Substations. Prepared by CIGRE magnetic Interference from Transceivers, Electromagnetic Compatibility (EMC)–
Working Group 36.04 (EMC within IEEE, Inc., New York Part 4: Testing and measurement
power plants and substations), 1997 techniques–Section 6: Immunity
(15) EN55011:1998 Electromagnetic to conducted disturbances, induced
(6) IEC 61000-6-5 (1999-03): Compatibility (EMC) - Emissions from by radio-frequency fields 1st ed.
Electromagnetic Compatibility (EMC) - industrial, scientific and medical (ISM) Geneva, International Electrotechnical
Part 6-5: Generic standards - Immunity equipment The European Committee Commission, 1996
for power station and substation envi- for Electrotechnical Standardization,
ronments (CD). Geneva, International 1st ed. Brussels, CENELEC 1998 (23) IEC 61000-4-8 (2001-03):
Electrotechnical Commission, 1999 Electromagnetic Compatibility (EMC)–
(16) EN61326-1:1997 Electromagnetic Part 4-8: Testing and measurement
(7) Code of Federal Regulations, Title Compatibility (EMC) - Emissions and techniques–Power frequency magnetic
47, Volume 1, Part 15 - Radio Fre- Immunity for Equipment for Measure- field immunity test 1st ed. Geneva,
quency Devices U.S. Govt. Printing ment, Control, and Laboratory use The International Electrotechnical
Office, revised October 1, 1999 European Committee for Electrotech- Commission, 2001
47CFR15.33 pages 664-665 nical Standardization, 1st ed. Brussels,
CENELEC 1997 (24) IEC 61000-4-9 (2001-03):
(8) IEEE Standard 430, 1992 Standard Electromagnetic Compatibility (EMC)–
Procedures for the Measurement of (17) EN55022:1998 Electromagnetic Part 4-9: Testing and measurement
Radio Noise from Overhead Power Compatibility (EMC) - Emissions techniques–Pulse magnetic field immu-
Lines and Substations, IEEE, Inc. 345 from information technology equip- nity test 1st ed. Geneva, International
East 47th St, New York, NY ment (ITE) The European Committee Electrotechnical Commission, 2001
for Electrotechnical Standardization,
1st ed. Brussels, CENELEC 1998

12 An Introduction to Electromagnetic Compatibility (EMC) Standards

 RESOURCE PAPER

(25) IEC 61000-4-10 (2001-03): frequency, immunity test. 1st ed.

Electromagnetic Compatibility (EMC)– Geneva, International Electrotechnical Appendix A: History of
Part 4-10: Testing and measurement Commission, 1999 EMC Standards
techniques–Damped oscillatory
magnetic field immunity test 1st ed. (32) IEC 61000-4-29 (2000-08): The 1930s introduced AM broadcast
Geneva, International Electrotechnical Electromagnetic Compatibility (EMC)– radio to many people, and with the
Commission, 2001 Part 4-29: Testing and measurement rising use of electric motors, railroads,
techniques–Voltage dips, short interrup- and signs, more EMI problems appeared.
(26) IEC 61000-4-11 (2001-03): tions and voltage variations on d.c. The Proceedings of the Institute of Radio
Electromagnetic Compatibility (EMC)– input power port immunity tests 1st ed. Engineers (IRE) addressed vehicle EMI
Part 4: Testing and measurement tech- Geneva, International Electrotechnical problems in 1932. (36) The IEC recom-
niques–Section 11: Voltage dips, short Commission, 2000 mended in 1933 that an "International
interruptions and voltage variations Special Committee on Radio Inter-
immunity tests 1st ed. Geneva, (33) EN61000-3-2:1995 Electromag- ference" (CISPR) be formed to quantify
International Electrotechnical netic Compatibility (EMC)–Part 3: the emerging EMI problems and describe
Commission, 2001 Limits - Section 2: Limits for harmonic interference measuring equipment for the
current emissions The European Com- 150 kHz – 1.605 MHz range. At the
(27) IEC 61000-4-12 (1995-05): mittee for Electrotechnical Standard- CISPR meeting in 1934, it was agreed
Electromagnetic Compatibility (EMC)– ization, 1st ed. Brussels, CENELEC that the tolerable limits for interference
Part 4: Testing and measurement tech- 1995 would preserve a 40 dB signal-to-noise
niques–Section 12: Oscillatory waves ratio when receiving the reference 1m
immunity test. Basic EMC Publication (34) EN61000-3-3:1995 Electromag- V/M field strength modulated to 20%.
1st ed. Geneva, International Electro- netic Compatibility (EMC)–Part 3: (37) Radiated emissions testing was
technical Commission, 1995 Limits - Section 3: Limitation of voltage initially addressed, but voltages "leaking"
fluctuations and flicker in low-voltage from power cords, polluting the unfilter-
(28) IEC 61000-4-13 (Ed. 1.0): supply systems The European Com- ed power network and re-radiating into
Electromagnetic Compatibility (EMC)– mittee for Electrotechnical Standard- space mandated that conducted emis-
Part 4-13: Testing and measurement ization, 1st ed. Brussels, CENELEC sions testing be addressed as well.
techniques–Harmonics and interhar- 1995 In 1934 the US Army Signal Corps
monics including mains signaling at a.c. issued SCL-49, "Electrical Shielding
power port, low frequency immunity (35) Power System Electromagnetic & Radio Power Supply in Vehicles."
tests - Basic EMC Publication 1st ed. Compatibility, EPRI Resource Paper, From 1934-1939 CISPR issued Reports
Geneva, International Electrotechnical M. Silva, F. Young, and R. Olsen, RI 1-8 specified receivers, field strength
Commission, 2001 December, 2000. measurements and artificial mains net-
works (AMN or LISN) to stabilize
(29) IEC 61000-4-16 (1998-01): (36) Curtis, Leslie E. "Electrical the impedance of the power being
Electromagnetic Compatibility (EMC)– Interference in Motor Car Receivers," supplied, so as to allow consistent
Part 4-16: Testing and measurement Proceedings of the Institute of Radio voltage measurements. (37)
techniques–Test for immunity to con- Engineers, vol. 20 no. 4, April 1932, The need for EMC increased during
ducted, common mode disturbances p. 674 World War II because of the growing
in the frequency range 0 Hz to 150 kHz numbers of electronic devices, such as
1st ed. Geneva, International Electro- (37) The History of Military EMC radios, navigation receivers, and radars.
technical Commission, 1998 Specifications, Warren Kesselman, Reports of interference on airplanes
Herbert Mertel, IEEE-EMC Society between radios and navigation equip-
(30) IEC 61000-4-27 (2000-08): Summer 2000 Newsletter ment were handled on a case-by-case
Electromagnetic Compatibility (EMC)– basis. EMC was made more urgent with
Part 4-27: Testing and measurement (38) Paul, C.R. Introduction to the deployment of life-critical guidance,
techniques–Unbalance, immunity test Electromagnetic Compatibility. communication, and sonar and radar
1st ed. Geneva, International Electro- New York: John Wiley & Sons, 1992. applications that tracked enemy ship,
technical Commission, 2000 submarine, air and terrestrial locations.
The earliest developments in Military
(31) IEC 61000-4-28 (1999-11): EMC Standards were driven by vehicle
Electromagnetic Compatibility (EMC)– EMI problems. (Figure 8) In 1942, The
Part 4-28: Testing and measurement US Army Signal Corps issued 71-1303,
techniques–Variation of power later modified into JAN-I-225 in 1945.

An Introduction to Electromagnetic Compatibility (EMC) Standards 13

RESOURCE PAPER

CISPR met again after the War in The end of the Cold War, softening Coupling – the transfer or pick-up of
1946, and issued standards on conducted demand for military hardware, and the electromagnetic energy from one circuit
interference measurement techniques and integration of the European Union (EU) to another by radiation, induction, or
recommended emissions limits and an in the 1990's began to shift emphasis conduction (or all three)
artificial mains network (LISN) for the away from MIL-STD 461 towards
widely used broadcast band. (37) Post- consumer, commercial, and light Current Probe – a transducer that
war projects centered on radio noise from industrial equipment covered under the converts current through its primary
transmission lines, and EEI (Edison EMC Directive 89/336EEC of the EU. opening into voltage at its output,
Electric Institute) and EPRI (Electric These European standards became the for the measurement of current spectra
Power Research Institute) extended this underlying methodology for high quality, in conductors
work to the 1000 kV range. (35) Several "world designed" products, which could
national EMC organizations were also be shipped to all regulated markets. Decibel (dB) – a numerical expression
formed after the war, with technical of the relative difference between a
committees to develop new standards. quantity and a reference level
EMC problems increased rapidly with
the introduction of solid-state electronics, Appendix B: Glossary Declaration of Conformity – a legal
beginning with the bipolar transistor in statement accompanying a product
the 1950s and the integrated circuit (IC) Anechoic Chamber – a test room that staing its conformity with the "essential
"chip" in the 1960s. The FCC licensed has walls and ceiling covered with ane- requirements" of the EMC Directive
Citizen's Band (CB) radio in the early choic absorber or radio-absorbent mater-
1960's, with a resulting increase in ial (RAM) to prevent reflected radio Dips – short, sub-cycle reductions in
incidents of EMI. (38) waves during an EMC test power input voltage (see Interrupts)
Microprocessors were introduced in (IEC 61000-4-11)
the 1970's. Apple Computer introduced Arcing – the current flow across an
the Apple II in 1976, and Radio Shack ionized air gap Electrical Fast Transient (EFT) (Burst)
responded with the TRS-80 in 1977, – simulates the rush of "showering arcs"
the same year power interference with Basic Standard – describes the phenom- that repeatedly form and extinguish
railroad signaling was addressed (in ena that are being simulated, such as when a magnetic field collapses across
September 1977.) (2) As computers electrostatic discharge or surge the opening contacts of a switch
became more common, commercial
EMC standards were urgently needed Burst – Electrical Fast Transient (EFT) EMC – Electromagnetic Compatibility-
and, in 1979, the FCC mandated CISPR - simulates the rush of "showering arcs" the ability of electrical or electronic
emissions limits for "digital devices" in that repeatedly form and extinguish equipment to function satisfactorily in
response to increasing reports of radio, when a magnetic field collapses across its intended electromagnetic operating
TV, and aircraft navigation interference the opening contacts of a switch environment without causing undesir-
from digital electronics. (Figure 3, Figure able or intolerable electromagnetic
4) The IBM-PC was introduced August Common Mode Current – a current disturbances to other equipment or
12, 1981 and the effect of power fre- flowing in the same direction along systems. Also, the engineering discipline
quency magnetic fields on computer all conductors in a circuit, including of studying, analyzing, and solving
monitors became the subject of the shield. electromagnetic interaction problems.
growing complaints. (38)
Compatibility Level – the specified EMI – Electromagnetic Interference –
electromagnetic disturbance level used as the impairment of the performance
a reference level for coordination in the of equipment or systems caused by an
setting of emission and immunity limits. unwanted electromagnetic disturbance
By convention, the compatibility level is
chosen so that there is only a small Emission – Electromagnetic energy that
probability that the actual disturbance travels outside the bounds of the initiat-
level will exceed it. Frequently, the ing device as conducted energy or radi-
95% probability level is defined as ated energy, or both
the compatibility level.
EN – Euronorms (European Standards)
Conduction – a coupling method by – Adopted standards have an EN prefix.
direct wire connection Prior to adoption, HD a harmonized
Figure 8. Jeep plant
document, prEN is a preliminary or

14 An Introduction to Electromagnetic Compatibility (EMC) Standards

 RESOURCE PAPER

provisional EN standard, and ENV is location where the product would Product Standard – the Standard that
a temporary (voting copy) EN standard. be used, such as commercial or heavy should be used for the guidance on
industrial locations testing of a particular type of finished
ESD – Electrostatic discharge – the product, if not available use a Generic
energy released by the flow of electric Harmonic Emissions – an emission Standards or TCF filing instead
current, usually resulting from the from a product that does not draw
mechanical separation of electric sinusoidal current, and hence produces Receptor – a circuit, device or system
charge. ESD can damage sensitive harmonic currents that enter the power (victim) that may suffer interference due
equipment and create impulsive system wiring, regulated under EN to noise
electromagnetic energy. 61000-3-2
Re-Radiation – indirect transmission
Essential Requirements – the EMC Immunity – the ability of a device or of RF energy across open space,
Directive mandates that a product not system to perform satisfactorily in the using wiring or other structures
disturb other products and that it have presence of a specific interfering electro- as secondary antennas
intrinsic immunity to outside interfer- magnetic environment
ence to enable it to operate as intended Shielded Enclosure – a room shielded
Incidental Radiator – a device that from external radio frequency electro-
European EMC Directive – incidentally generates radio-frequency magnetic waves with filtered power to
89/336/EEC was adopted in 1989. This energy during the course of its opera- facilitate EMC testing of equipment
Directive sets out the legal requirements tion, although its not intentionally (also called a "Faraday cage or
on EMC for all electric or electronic designed to do so screened room")
equipment to be placed or used in the
Common Market/European Economic Induction – a process by which electro- Surge – lightning strike simulation test-
Area. The European legislation covers magnetic energy is transferred from a ing on power and I/O lines, typically to
emissions as well as immunity and source to a nearby parallel conductor IEC 61000-4-5
came into effect in 1992. An amending or circuit
Directive (92/31/EEC) was adopted in Susceptibility – the threshold for
1992, which introduced a transitional Interrupts – cessation of electrical interference in a device or system
period that ended on December 31, service for several seconds, which may
1995. Enforcement of the EMC cause rotating machines to generate Technical Construction File (TCF) –
Directive is the responsibility of smooth, slow voltage changes (IEC used to demonstrate EMC compliance
government-appointed authorities 61000-4-11) where:
in individual countries. · There is no harmonized
Line Impedance Stabilization Network European Standard
EUT – Equipment Under Test – a (LISN or AMN) – sets the RF imped- · Standards exist, but can only be
device or system (and its associated ance of the power line and derives a applied in part
cables) used for EMC testing that sample of the noise voltages being · Testing to harmonized Standards is
is representative of a product to ejected from the mains of the EUT not practical due to size, location, etc.
be marketed
OATS – Open Area Test Site – used for · The large number of product
conformance testing for radiated emis- variations makes testing all
sions. Reflected radio frequency waves combinations impossible
Flicker – an emission from a product are a problem and no objects, structures, · Other recognized EMC Standards
whose variance in current demand or wires should be in the area. A good were used, such as MIL-STD, etc.
causes a corresponding variance in site should also have very low ambient
the luminance of incandescent lamps RF levels in the test frequencies of inter- In the past, the TCF Route to Market
connected in parallel, regulated under est. Requirements for OATS certifica- required the use of a "Competent Body"
EN 61000-3-3 tion are detailed in CISPR 16.1 and but that may change towards Self-
ANSI C63.4 Declaration in the future.
Gap discharge – electrical arcing caused
by loose or broken hardware in the Performance Criteria – standardized Unintentional Radiator – a device that
distribution power system guidance on the evaluation of the per- incidentally generates radio-frequency
formance of an EUT while it is being energy during the course of its operation
Generic Standards – EMC Standards subjected to Immunity tests although its not intentionally designed
that call for testing based on the to do so (Incidental radiator)

An Introduction to Electromagnetic Compatibility (EMC) Standards 15

RESOURCE PAPER

16 An Introduction to Electromagnetic Compatibility (EMC) Standards

 RESOURCE PAPER

The following illustrations are provided as aids to

making overhead or 35 mm transparencies.

An Introduction to Electromagnetic Compatibility (EMC) Standards 17

 RESOURCE PAPER

18 An Introduction to Electromagnetic Compatibility (EMC) Standards

 RESOURCE PAPER

Basic
Standards
Generic
Standards
Product
Standards

An Introduction to Electromagnetic Compatibility (EMC) Standards 19

 RESOURCE PAPER

EN 61326-1 CONDUCTED EMISSION LIMITS FOR CLASS A EQUIPMENT

CLASS A quasi peak CLASS A average

90

80

70
EMISSION LIMIT (dBµV)

60

50

40

30

20
0.1 1 10 100
FREQUENCY (MHz)

20 An Introduction to Electromagnetic Compatibility (EMC) Standards

 RESOURCE PAPER

EN 61326-1 EMISSION LIMITS FOR CLASS A EQUIPMENT

dBµV/m quasi peak at 10 m dBµV/m quasi peak at 30 m

70

60

50
EMISSION LIMIT (dBµV/m)

40

30

20

10

0
10 100 1000
FREQUENCY (MHz)

An Introduction to Electromagnetic Compatibility (EMC) Standards 21

 RESOURCE PAPER

22 An Introduction to Electromagnetic Compatibility (EMC) Standards

 RESOURCE PAPER

An Introduction to Electromagnetic Compatibility (EMC) Standards 23

 RESOURCE PAPER

24 Power System Electromagnetic Compatibility

 RESOURCE PAPER

Power System Electromagnetic Compatibility 25

 About EPRI
EPRI Resource Papers
EPRI creates science and technology solu-
tions for the global energy and energy services
esource papers provide scientific and/or engineering information on
R selected environmental, health, or electromagnetic compatibility issues
of interest to professionals in the energy industry. Each paper supplies
industry. U.S. electric utilities established the
Electric Power Research Institute in 1973 as
a nonprofit research consortium for the
benefit of utility members, their customers,
detailed background information on a narrowly defined topic, including and society. Now known simply as EPRI, the
key concepts and scientific perspective, as well as a list of other information company provides a wide range of innovative
resources. products and services to more than 1000
energy-related organizations in 40 countries.
A typical reader of resource papers is a technically trained professional who EPRI’s multidisciplinary team of scientists and
engineers draws on a worldwide network of
needs a concise, thorough update on a topic outside of his or her area of
technical and business expertise to help solve
expertise. today’s toughest energy and environmental
problems.
EPRI. Electrify the World

© 2002 Electric Power Research Institute (EPRI), Inc.

All rights reserved. Electric Power Research Institute
and EPRI are registered service marks of the Electric
Power Research Institute, Inc. EPRI. ELECTRIFY THE
WORLD is a service mark of the Electric Power
Research Institute, Inc.

Printed on recycled paper in the United States

of America
1005494

EPRI • 3412 Hillview Avenue, Palo Alto, California 94304-1395 USA • PO Box 10412, Palo Alto, California 94303-0813 USA
800.313.3774 • 650.855.2121 • askepri@epri.com • www.epri.com