Introduction This article will serve as an introduction to the topic. It is aimed at the people who have been told by their management, “You are now my EMC person. Go figure out what it is and how we must deal with it!” It will not be an all-encompassing treatment of the subject, but it will provide the reader with a start and some ideas of where to go for more … [Read more...]
About the Author
Ghery Pettit
Ghery S. Pettit, NCE is the President of Pettit EMC Consulting LLC. He is a graduate of Washington State University and is a Life Senior Member of the IEEE. He has worked in the EMC world for the past 42 years in positions with the US Navy, Martin Marietta Denver Aerospace, Tandem Computers, Intel Corporation and now as an independent consultant. Mr. Pettit is a past President of the IEEE EMC Society and currently serves as Chair of CISPR Subcommittee I, which is responsible for emissions and immunity standards for broadcast receivers, ITE and multimedia equipment. He has designed and operated EMC laboratories, provided EMC analysis, design, troubleshooting and testing support for a variety of projects and contributed to various EMC standards such as ANSI C63.4, CISPR 22, CISPR 24, CISPR 32 and CISPR 35. Ghery may be reached at [email protected] or at (360) 790-9672.
New and Proposed Changes to CISPR SC I Standards
Are you familiar with CISPR 32 and CISPR 35? CISPR 32 was originally published in 2012, followed by a pair of corrigenda and then the 2nd edition was published in 2015. CISPR 32 replaced CISPR 13 (Broadcast receivers emissions) and CISPR 22 (ITE emissions), both of which were withdrawn by the IEC on March 5, 2017. In the EU CISPR 32 is published as EN 55032 and it has … [Read more...]
EMC Laboratory Selection Audit Items
Introduction This blog will provide the reader with an introduction to some of the items that need to be looked at when auditing an EMC laboratory with an eye to placing them on your company’s approved lab list. This is not an in-depth look at each item but is based on my experiences auditing laboratories (both in-house and 3rd party) over a number of years. Key … [Read more...]
Does the Number of Bypass Capacitors for a Chip Matter?
How do you decide on the size of a bypass capacitor (or capacitors) for your project? Do you need multiple capacitors to bypass a specific chip? Are multiple value capacitors important for a given use? Do you subscribe to the old Wife’s Tail about having a couple capacitors a couple orders of magnitude different in value in parallel? Here is one take on the subject for you … [Read more...]
Emissions Test Facility – OATS vs SAC?
You’ve been tasked by management to build a new, from scratch, EMC test facility. Among other items, you need to decide between an Open Area Test Site (OATS) or an RF Semi-Anechoic Chamber (SAC). How do you decide? To someone who has been there, done that, the choice is clear, but what are some factors that might sway the decision one way or the other? Design of an … [Read more...]
What is the Number One Item That Causes EMC Problems at the Board Level?
There are many “rules” for laying out a printed wiring board (PWB) to minimize generation of EMI from a board. These cover a wide range of issues that are important. Some more than others, but all can be important. But, if you were to ask what the number one item on the hit parade would be, what would you say? What are the important factors to consider when laying out a … [Read more...]
Proposed Changes to CISPR SC I Standards
Are you familiar with CISPR 32 and CISPR 35? CISPR 32 was originally published in 2012, followed by a pair of corrigenda and then the 2nd edition was published in 2015. CISPR 32 replaced CISPR 13 (Broadcast receivers emissions) and CISPR 22 (ITE emissions). In the EU CISPR 32 is published as EN 55032 and it has superseded EN 55013 and EN 55022. By now you should all be … [Read more...]
Substitution Source Measurements
In today’s EMC testing world testing is very often automated, using well calibrated test equipment. The operator sets up the EUT and support equipment, sets up the test equipment, fires up the software on the computer designed to automate the test, clicks on “Go” and sits back to watch the blinking lights. After a while the test is complete and a file is generated containing … [Read more...]
Do your people really know how to perform a conducted emissions test to ANSI C63.4 or CISPR 32?
Oftentimes when a new person is hired to perform conducted emissions testing in a laboratory they know little about EMC and even less about how to perform a test. There is a training period where the new person learns how to perform a test using whatever software the lab has been using. The new person is well trained in how to perform the test with the automation working, … [Read more...]
An Engineering Ethics Question for Today
I’ve been presenting a seminar on engineering ethics to students in the Electrical Engineering Department at Washington State University for a number of years. I’ve started off with a video of the Challenger explosion and the questions leading up to it as expressed by Roger Boisjoly, a Morton Thiokol engineer. Roger Boisjoly had studied data showing that the field joint … [Read more...]
