Selecting An AC Line Filter For Switching Power Supply Applications
by Kevin Parmenter, Chair, and James Spangler, Co-chair, PSMA Safety and Compliance Committee , How2Power Today, Oct 17 2019
Focus:
While guidelines have been written on how to select EMI line filters, many system engineers
still aren’t aware that they need EMI filters. When they do realize they need one, they
often select a filter without regard to their actual filtering needs. They may also ignore
the impact of the filter on other requirements (such as leakage current), and issues such
as customer support. In this article, the authors identify some of the popular bad
practices being used to choose EMI line filters, explain why they’re wrong and provide a
quick step-by-step guide to proper filter selection that will help designers avoid the
common pitfalls. They identify the key criteria you’ll need for filter selection including
rules of thumb and key specs. Popular EMC standards and standards organizations are also
noted. Armed with this information, designers will be better equipped to apply the existing
EMI selection guides and tools, some of which are referenced here.
What you’ll learn:
- How to select EMI line filters for power supply applications
- How to avoid common mistakes in the selection of EMI line filters
- How to understand the value of customer support when selecting an EMI filter supplier
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