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This set of course modules is intended to help product developers come to grips with the EMC aspects of their designs. It is based on Elmac Services' standard 3-day training course (Now becomes the TUV SUD academy's EMC training course, taught by Dr. Min Zhang). Elmac Services was formerly under the ownership of Mr. Tim Williams, who retired in 2021. Subsequently, Tim entrusted Min with the responsibility of continually updating the course content and ensuring the service remains operational, enabling engineers worldwide to benefit from this self-taught resource. You can still purchase Tim's very popular EMC book "EMC for Product Designers, fifth Edition".

Please visit our website for more contents. You are welcome to send corrections and ideas for future development of the course to us, using the e-mail link in the header of each topic page.

How to use this course

The course is organised into sections with topics as per the table of contents; many topics have a link to questions at the end of the page, or you can go straight to the questions via the contents page. You can browse particular subjects using the index or table of contents, or work through it in order, as you prefer. There is also a glossary and a list of frequently asked questions.

As we continuously update our materials, the content you are currently viewing may not be the latest version due to cached data in your browser. Therefore, we strongly recommend checking the most recent version, which is V2.0 at the moment, highlighted in the course front page. If you encounter a different version, please clear your browser cache (or simply use private/incognito mode) to access the latest version of the training course.

Electromagnetic Compatibility

All electrical and electronic devices can generate electromagnetic interference, and can be susceptible to it. The ability of a device to operate within the limits of interference immunity and suppression is known as electromagnetic compatibility (EMC).

EMC is concerned with two things:

ensuring that other users of the radio spectrum, and for that matter the public power supply, are not inconvenienced by operation of another piece of equipment, and

that the operation of that equipment itself is not unacceptably affected by external interference.

Historically, EMC came about with the realisation of interference problems between electrical machines and broadcast receivers in the early twentieth century. At that time it was known as radio frequency interference (RFI). With the spread of electronics and the increase in both radio and wired communication media, the issues have extended beyond just the radio spectrum to encompass everything "from DC to daylight".

Some illustrations of EMC problems in real life can be found under the "Examples" section of this course.

The formal definition of EMC can be found in the International Electrotechnical Vocabulary IEC60050-161:

“The ability of a device, equipment or system to function satisfactorily in its electromagnetic environment without introducing intolerable electromagnetic disturbance to anything in that environment”

It emphasizes the two complementary aspects of immunity from interference – to ensure the correct operation of the equipment – and the control of interference emissions, to protect users of the radio spectrum and the public power supply.

The electromagnetic environment as referenced in the above definition is itself defined as “the totality of electromagnetic phenomena existing at a given location”. A wide variety of such phenomena are encountered which are complex and time-varying, such that it is only really possible to obtain a description of the environment by the use of statistical methods. No frequency limits are specified, nor are the routes by which the disturbances may be propagated. But for practical purposes we have to classify the possible phenomena to be able to deal with them:


At radio frequency

At low frequency


From radio frequencies

From low frequencies

From transients

EMC cannot be proven by design standards, although there are many good practice design techniques which help to ensure it, and this course covers these. But there are several tests that can be performed and these are standardized for several sectors. The section on standards compliance describes the main sources of standards and what they require.