EMC in a Nutshell

These days [2019], a global trend of increasing automation, wireless communication and safety requirements can be observed. This leads to the conclusion that Electromagnetic Compatibility (EMC) is a topic which will bother thousands of engineers for many years to come. This simply because EMC ensures seamless and safe operation of devices and machines beside each other.

"In case you have never heard about EMC before or you have just started studying engineering, this article is a door opener for you to the fascinating world of EMC."

What is EMC?

EMC stands for Electromagnetic Compatibility. Electromagnetic Compatibility means that all electronic and electromechanical devices and machines run in their intended environment besides each other without interfering. In other words: each device must not be interfered by other devices and vice versa.

The expressions and definitions involved in EMC are explained in the picture below:

How EMC is structured.

EMC Regulations

Every electronic device/machine on the market must be EMC compliant, meaning it must fulfill the EMC regulations (laws, directives) for the intended use of the product. Which EMC regulations and directives are applicable for which product is defined by the country (or customs union) where the product is sold. A company which is the legal manufacturer of a product must proof compliance with the regulations. This is done with a conformity assessment. In case of a product which contains electronics, an EMC conformity assessment is necessary. Such an EMC conformity assessment usually comprises the proof of...:

...the manufacturing process control (quality)....the conformity of the product regarding the applicable EMC standards (EMC test).

Many countries and customs unions also define that the companies which import (importer) and/or sell a product, must ensure that the product is compliant to the laws and directives of the country where it is imported or sold, respectively.

EMC Standards

EMC Standards define terms, rules and test methods for EMC. Furthermore, they specify emission limits and minimum immunity test levels for electric and electromagnetic emissions and immunity of electromechanical and electronic products. EMC Standards help to make measurements comparable and repeatable by defining the test methods and the test equipment and the test environment. And most important, EMC Standards have the purpose of bringing harmonization to EMC testing, in the best case: a global harmonization.

"Globally harmonized EMC Standards help to increase free trade and prosperity."

Which EMC Standards to apply for compliance? This is a tricky part! As mentioned above, the applicable standards are defined by the responsible governmental administrations, organizations, commissions or committees. So the process of finding the applicable standards often differs from country to country. However, to give you an idea how it works e.g. in the European Union (directive 2014/30/EU), we drew a flow-chart, which is based on the EMCD Guide. Other useful tips:

Have a look at the CISPR Guide and search for your product category. Check which EMC Standards your competitors applied. Ask your EMC test laboratory for advice which EMC Standards to apply.

EMC vs. EMI.

EMI stands for Electromagnetic Interference and is often mixed up with EMC. EMI means that one electronic device/machine A is causing disturbance to another electronic device/machine B, which is in the surrounding of device/machine A.

What is the difference between EMC and EMI? Now, an EMC compliant product has to be tested on EMI during its development. For an EMC compliant product, EMI should not happen any more. This is due to the fact that EMC compliant products proved their electromagnetic immunity to be high enough and their electromagnetic emission to be low enough to work seamlessly in its predefined environment.

Coupling Paths

One important concept in EMC is the concept of coupling paths. To start off, let's see what parts are involved when Electromagnetic Interference (EMI) happens and why focusing on coupling paths is so important:

• Source: In real world, there are sources of unwanted electric or electromagnetic noise, like mobile phones or heavy industrial machines (during EMC testing, these sources of noise are artificial and as close as possible to the real world, e.g. ESD generators, burst generators, surge generators, antennas etc.).

• Coupling Path: The noise needs a path from the source to the victim to affect the victim. This path is called the coupling path or coupling channel.

• Victim: The victim is the receiver or receptor of the noise.

Coupling Paths.

We will write more in a future post about the different types of coupling paths and how to deal with them.

Free Education

We hope the introduction to the topic Electromagnetic Compatibility helped you to get an idea. We hold the believe that EMC will be a hot topic in the near future. Therefore, we offer free education about it.

-The Academy of EMC