Title: Testing for EMC Compliance -Approaches
and Techniques
Authors: Mark I. Montrose and Edward M. Nakauchi
Publisher: Wiley/IEEE Press
Year Published: 2004
ISBN: 0-471-43308-X
Number of Pages: 460
Testing
for EMC Compliance–Approaches and Techniques, is the third
in a series of books on EMC by Mark I. Montrose and the first
with co-author Edward M. Nakauchi. The first two books dealt with
EMC design and layout for printed circuit boards. This book’s
focus is on EMC testing as the title suggests. Testing, as described
in this book, is heavily weighed towards commercial requirements,
(i.e., CISPR, FCC, etc.), while also having applicability to MIL-STD
testing.
It is the opinion of this reviewer that this book should be mandatory
reading for every engineer that needs to witness or perform EMC
testing of electrical and electronic devices for compliance with
international standards. Additionally, product development managers
should read this book to understand the ramifications of not fully
testing early during the design cycle to gain knowledge of their
product’s performance in a world immersed in interfering
sources. Testing details and descriptions of the “whys”
provided in this book are most helpful in understanding the principles
of EMC compliance verification and the interpretation of test
results.
This book is divided into nine chapters preceded by a Preface
and Acknowledgements, followed by two Appendices, a Glossary,
Bibliography and Index.
Chapter 1 “Introduction” (16 pages) contains a narrative
for the need to comply with requirements followed with definitions
and then an excellent description of the nature of interference.
This is followed by a short overview of product testing including
the test environment, self-compatibility, and validation of measured
data. There is also an introduction to problems that may be encountered
during emissions testing that are expanded upon in subsequent
chapters. This first chapter also contains an explanation on the
differences between time domain and frequency domain analysis
and when to use each properly. Finally, EMC testing methodologies,
i.e. the differences between development and diagnostic testing,
and furthermore the differences between compliance and pre-compliance
testing, is described in detail. This too is augmented in later
chapters so that the reader is well informed of the unique distinctions
of each.
Chapter 2 “Electric, Magnetic, and Static Fields”
begins with the relationship between each field. This discussion
is essential for the reader to understand the ensuing text of
this chapter. After this presentation, the authors describe in
great detail the different methods of noise (EMI) coupling for
both conducted and radiated emissions. This further develops the
reader’s understanding leading to even more detailed analysis
on common-mode vs. differential-mode currents, and conversion
from differential to common-mode noise including equations. Finally,
the authors describe static fields including electrostatic and
tribo-electric fields and the resultant failure modes for each.
Chapter 3 deals with the “Instrumentation” necessary
to measure time domain and frequency domain electromagnetic energy.
Several pages are devoted to oscilloscopes, spectrum analyzers,
frequency selective voltmeters (receivers), and correlation analyzers.
The differences between pre-compliance and compliance instrumentation
is fully described. The use of peak detection versus quasi-peak
and average is examined completely as well as when to use each.
Coherence factors for signal correlation are also described in
this chapter.
In Chapter 4 the authors discuss the use of “Test Facilities”
including Open-Area-Test-Sites (OATS), chambers (shielded enclosures)
and Transverse Electro-Magnetic (TEM) cells. This chapter clearly
can be used to understand test facility differences for commercial
vs. MIL-STD testing. Detailed information about test setup configurations
for the system, and power and signal interface cables are presented
along with operating conditions and measurement precautions. The
distinction between anechoic, semi-anechoic, reverberation and
shielded enclosures, and the use of each is fully described. The
TEM and G (GHz) TEM cells are shown to be adequate facilities
to use for physically small device testing.
“Probes, Antennas, and Support Equipment” are presented
in Chapter 5. Although this chapter could have followed Chapter
3 on Instrumentation and before Chapter 4 on Test Facilities,
it nevertheless is absolutely complete on the chapter title subject.
In this chapter, not only are transducers described well including
their usage, they are shown with schematics and drawings in addition
to how to fabricate many of these sensors. Appendix A of this
book goes into greater detail on the fabrication of these devices.
The definition of transfer impedance as it pertains to current
probes is given. Line Impedance Stabilization Networks (LISN’s)
are also completely described. Voltage probes, absorption and
insertion clamps for capture and injection of interfering signals
(noise) are detailed. Homemade probes known as small “sniffers”
are also discussed. Reading this chapter requires patience because
it is packed with very useful information.
Chapters 6 and 7 of this book contain the “meat” of
the title subject matter and are the most important reasons for
readers to purchase the book. These two chapters talk about “Conducted”
and “Radiated” testing, the two fundamental parameters
of EMC compliance.
Chapter 6 begins with an overview of conducted currents including
the difference between common and differential-mode currents and
their coupling paths. This is a bit of a refresher considering
that both common-mode and differential-mode currents were previously
discussed in Chapter 2. What are new in the beginning of this
chapter are conducted test requirements. Next, this chapter describes
general statements about the performance of conducted current
tests, followed with emissions and immunity (susceptibility) testing.
Conducted emissions testing is limited to the most commonly applied
tests because of this book’s close ties to commercial products,
especially related to AC power mains and potential problems that
may be encountered when making such measurements. This is followed
with in situ emissions testing of systems and installations.
Chapter 6 discusses conducted immunity (susceptibility) testing
in both the frequency and time domains. Like testing for conducted
emissions, this part of the chapter is limited to conducted immunity
testing of AC power mains, probably for the same reason. Fast
transient, burst and surge testing is discussed. For the next
three subjects, “Conducted RF Current Immunity”, “AC
Mains Supply, Dips, Dropouts, and Interruptions”, and “Power
Line Harmonics”, the authors establish a format for this
book to flow from how the noise got there, to how to measure it,
to diagnosing and fixing the problem. This chapter ends with measurement
of “Voltage Fluctuation and Flicker”.
Chapter 7 begins with a general discussion about investigative
emissions testing in a laboratory or office environment, and then
moves on to pre-compliance testing and analysis of the results.
Next, the authors discuss formal EMC qualification radiated emissions
testing followed with a dissertation on in situ testing of systems
and installations. The remainder of this chapter is devoted to
radiated immunity (susceptibility) testing. This part of Chapter
7 is divided into three subchapters. First there is radiated immunity
testing in the traditional sense, i.e. the generation of electric
fields and immersing the test item(s) in that field. The next
part deals with electrostatic discharge (ESD) testing. This part
of Chapter 7 is well thought out and complete. The last part of
Chapter 7 deals with power frequency magnetic fields and the testing
involved to evaluate a disturbance from this particular type of
field.
The last two Chapters of this book deal with “Troubleshooting”
which is fault or failure isolation and appropriate corrective
action. This is by all means the hardest part of being an EMC
engineer, and requires many years experience to be proficient.
Chapter 8 describes “General Approaches to Troubleshooting.”
This chapter describes general system troubleshooting techniques
including unique emissions and immunity testing and potential
problems encountered during evaluation of those test results.
This chapter also gives a systematic approach to troubleshooting
techniques to isolate problems. The ever-present question about
repeatability of one’s test results is discussed in some
detail and continues to unexpected problems that may be encountered
after production has begun. This chapter ends with several examples
and case studies.
Chapter 9 deals specifically with “On-Site Troubleshooting
Techniques.” This chapter is filled with tricks of the trade
to isolate problem areas quickly when evaluating and troubleshooting
installed and working systems.
As previously stated, Appendix A contains a great detail of information
about fabrication methods for building special probes useful for
isolating noise sources emanating from equipment or circuits.
Appendix B contains 58 pages of a test procedure useful to the
reader who wishes to create their own test laboratory, or to repeat
a particular test that failed at a commercial test facility.
The authors have developed a logical approach to understanding
testing for EMC. The examples and equations are most helpful in
understanding the mechanisms involved for coupling of interfering
signals (noise) to victim equipment and circuits. The conversion
from common-mode conducted current to a radiated electric field
is particularly useful in understanding the radiated emissions
coupling mechanism. EMC
About the Book Review Guest Associate Editor
Larry G. Campbell has worked in the
EMI/EMC field for nearly 44 years. At present he is a Senior Contractor
for MEI Technologies headquartered in Houston, Texas with local
offices in Littleton, Colorado where Mr. Campbell is currently
contracting with Lockheed Martin supporting a variety of space
programs. Mr. Campbell holds a California professional engineers
license in Quality Engineering and is a NARTE certified EMI/EMC
Engineer. Mr. Campbell’s employment history spans the history
of the aerospace industry. He started in the industry in 1962
working for Autonetics in Downey, California, then a division
of North American Aviation (the maker of the P40 Mustang and the
F86 Super Saber Jet). Mr. Campbell worked on the Minuteman I,
II and III, radar systems and submarine systems, as well as the
Apollo moon landing mission while at Autonetics. After five years
in the RFI test laboratory at Autonetics, Mr. Campbell went to
Collins Radio Company in Newport Beach, California. At Collins
Radio Company, Mr. Campbell was instrumental in the development
of TEMPEST and EMI testing techniques applied to secure communications
systems still used throughout the industry. Seven years after
joining Collins Radio Company, Mr. Campbell left to manage a now
defunct R.F. shielded enclosure manufacturing business. Mr. Campbell
then spent the next three years at Hughes Aircraft Company in
Fullerton, California managing the EMI test laboratory performing
EMI and TEMPEST tests. Mr. Campbell was recruited by Martin Marietta
in Colorado to work on the Peacekeeper program in 1979. He then
spent the next 22 years working on the Peacekeeper and a variety
of programs that followed. Mr. Campbell retired from Lockheed
Martin in 2001 and four months later went to work as a contracting
engineer for MEI Technologies.
Book
Review