The Lowdown on EMC and EMI

Podcast Transcript

Jeff: Welcome to RECOM's Powerful Podcast, where we discuss new topics and products. I'm Jeff Deutschman, your product moderator. From a quarter watt up to 2kW, whether the power is required for an industrial setting, a new IoT gadget, or a high-end medical-grade device, RECOM has you covered.
In this episode, we'll be discussing EMI and EMC. Louis, thanks for joining the podcast. Can you begin telling us the difference between EMI and EMC?

Louis: Hi, Jeff. EMI is electromagnetic interference, which are disturbances generated by electrical components, while EMC stands for electromagnetic compatibility, which is the ability for electronic devices to resist these disturbances and not introduce any intolerable electromagnetic disturbances into the environment.

Jeff: Hey, easy for you to say. So, EMI is the problem then, while EMC is the ability to cope with the problem.

Louis: That's right. There are different standards for EMC, such as EN55022 and EN55032, but this is then further broken down into the categories of conducted and radiated emissions. To find out these emission levels, highly controlled tests are conducted in a special EMC chamber.

Jeff: Very interesting. Back to what you said about electrical components generating EMI. I take it that includes power supplies.

Louis: Yes, power supplies included. That is why it is important to have a proper EMC filter. Some of the RECOM power supplies come with EMC filtering already built in, but others require a few additional components, typically just an inductor and capacitor.

Jeff: Okay, how would I know what values I need for the additional components for my RECOM power supply?

Louis: The datasheet will have an EMC filter circuit shown. There will be a table for what values the components will need to be. There are two levels you can pick components from, either Class A or Class B.

Jeff: Good to know we have the information right on the datasheet, but what is the difference between Class A and Class B?

Louis: Good question. Class B is a stricter EMC requirement than Class A. This is true for both the conducted and radiated emissions.

Jeff: So, if the power supply is in an environment where other components are sensitive to EMI, it would be best to go with the Class B filter component list. What are some of our products that have the Class B filter already built in?

Louis: Many of the AC/DC converters offered by RECOM, such as the RAC03-K and RAC10-K/277, have Class B EMC capability without any external components.

Jeff: Outstanding. Any other important considerations I need to make with using the RECOM recommended filters?

Louis: Sometimes a wide capacitor which spans the isolation boundary is used in the recommended filter. It is important that the withstand voltage of this capacitor is at least the isolation rating of the converter. The datasheet will have this considered for the recommended component, but it is good to know the reasoning.

Jeff: Excellent. How about the applications for where our power supplies are being used? Any EMI considerations here?

Louis: Board layout can greatly impact EMI performance. For the board-mounted AC/DC and DC/DC converters, it is best practice to keep the PCB traces short to reduce EMI by having shorter current loops.

Jeff: Louis, this is all great information, but I still want to learn some more about EMC. Where can I go?

Louis: No problem. EMC is a complex topic. The RECOM website has some great resources, including whitepapers and videos. RECOM also has webinar trainings hosted throughout the year on different EMC topics. At the end of the webinar, there is a question and answer section which you can ask more questions. You can register on the website.

Jeff: Louis, this is awesome information. Thank you very much. We'll have to check this out. Well, that about wraps it up for this episode of RECOMs Powerful Podcast. Be sure to listen next time when we delve into the pros of another RECOM topic. As always, please contact your regional sales manager for any samples or pricing information. Our applications engineers are always happy to assist you with any technical questions or requests. You can email them at techsupportamericas@recom-power.com. Until then, have a great day and always remember, RECOM powers your products!