A close-up of a small electronic device being soldered onto a circuit board.

EMC Standards: What Are They, and Why Do They Matter?

Everyone wants the products they purchase to work as intended. These are product requirements.

Furthermore, nobody wants the products they purchase to stop working when placed on, say, a washing machine or near an electric motor. These are EMC requirements.

There are many, many different EMC standards you may be required to meet in the course of electronics design. In this post, we will start by understanding how EMC standards are set and why they matter. We will also take an introductory look at a very common generic set of standards, the IEC 61000-4-X, set by the International Electrotechnical Commission.

Defining EMC Requirements

Electromagnetic compatibility (EMC) requirements can be challenging to define, for it is impossible to test every new electronic product in proximity to every existing product on the market. A Bluetooth speaker may be placed beside a microwave, for example, or carried by a person riding an e-bike. These are completely different devices hoping to work properly in close proximity. How immune and robust should the Bluetooth speaker be to the e-bike’s motor, and vice versa?

Here’s another example: A hand-held toy transceiver radio (walkie-talkie) is destined for a domestic market, maybe for use by kids in their house or a park. A professional security transceiver is destined for a factory or an electrical substation, i.e., an industrial market. And yet another transceiver might be destined for use in an oil refinery, a specialized market with stringent ATEX spark ignition requirements.

The same base product technology is destined for different environments. This is the key to defining EMC requirements: basing the requirements on where the product is intended to be used.

The market, by the way, is just one piece of the intended environment; different geographical regions also have different EMC standards. When designing a new product, pay close attention to its intended geographical market, and be sure to check the EMC regulations for that region. Intuitively, you might think the region shouldn’t matter, but unfortunately, evolution has the world driving on different sides of the road.

What’s in an EMC Standard?

EMC standards guide electrical engineers on what equipment they need to test with, how a test system is calibrated, how something should be tested, how to conclude the outcome, etc. Standards also contain very valuable information for product design and application engineers as to what the product will get exposed to during testing. These standards can often be so generic that experience is necessary to ensure the product is presented in a way that tests it thoroughly and fairly. Each country signs up to these common standards so as to have a common understanding and playing field by which to govern the electromagnetic quality of products in an increasingly global market.

Industrial Standard IEC 61000

We will cover various market and geographical environments over the course of time, but here we will touch on just one example, the common Industrial Standard IEC 61000. Industrial standards apply to products that are destined for factory automation, manufacturing, and other industrial environments. The IEC 61000 standards can be more stringent than those in other markets because of the importance of functional reliability in the intended environments.

The IEC 61000 standards explain how to measure the electromagnetic performance of a product destined for the industrial market. For example, IEC 61000-4-2 details how to test a product’s immunity to Electrostatic Discharge (ESD). IEC 61000-4-5 explains how to test its immunity to lightning strikes. IEC 61000-4-4 shows how to test its immunity to fast transient signals. Any product you design will have to meet multiple EMC standards such as these to be approved for market release.

The obvious next question is, “What maximum emissions (disturbance) levels is a product allowed to generate?” In other words, what unwanted electromagnetic interference signal is the product allowed to produce before it is deemed too noisy, so as to reasonably expect neighboring products will continue to function properly in the intended environment? Standards such as IEC 61000-4-20 provide guidance on how to measure a product’s disturbance levels.

We will delve into detail on examples of immunity and emissions standards in later blog posts. For now, let it suffice to understand the value that EMC standards provide (even if meeting them can seem like a major pain!).

Meeting EMC Standards: Some Practical Advice

All EMC regulations boil down to this point: Your product can’t emit too much energy, nor can it be too sensitive to other products’ energy; either way, it will never get approved for sale. However, neither total immunity nor zero emission should be considered a realistic goal. The price of perfection in EMC tends to run high, in terms of both cost and development time.

So, while we don’t say that the Bluetooth speaker will not be affected by the e-bike, we do decide how immune the speaker should be in the environment where it is intended to work. If you do bring the speaker close to your e-bike, they will change each other’s electromagnetic field but should not noticeably affect each other’s performance. Therefore it is wise to be practical and a little forgiving, for the consequence of demanding total immunity is cost, cost, cost.