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Role of EMI X1, X2, Y1, Y2 Capacitors Ratings

10818399_10152509408852219_5757913693783094151_oUnderstanding what X2 or Y1 capacitors actually are and are not is important when designing them into an AC-mains connected power supply.  Recently Electronic Products Magazine ran an article I wrote on the proper role of X and Y safety rated EMI Capacitors.

The X2 capacitor rating means different things to different people–except for UL.  When I wrote this article to discuss some common misconceptions around what X2 Rated Capacitors are, and how they can be properly used.

In case the PDF reader doesn’t load, it’s on Page 20 of the November 2014 issue.

You can see the full article with the EP Reader, by clicking here.

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Events

Introduction to Polymer Capacitors

November 2013’s issue of Electronic Products features an article on the cover titled “Introduction to Polymer Capacitors.”  The author is, well, me. This article explains the differences between traditional MnO2-Tantalum and  Polymer-Tantalum capacitors.  Previously I explained these differences in the post on the fire hazard the Arduino GSM shield poses (due to improper derating).

You can find the Electronic Products article wherever magazines are sold or here:  Introduction to Polymer Capacitors.  Check below for links to high-resolution pictures.

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Arduino

Ouch. The Arduino GSM shield has a pretty serious design flaw, with its capacitors.

Tantalum is a really misunderstood capacitor. Well, all capacitors are misunderstood, but that’s a subject for another post. I ran across this post on the Arduino forums on the Arduino GSM shield. In the post, ddewaele, reports that the shield blew up, catching fire. At first some might think it was due to abuse by the user. While it is possible that reversing the polarity or applying over-voltage could cause a catastrophic failure, it is also possible that the user doing nothing wrong could result in the same failure mode!

Wait, what? So what gives? Well, there’s two things to understand. First, Tantalum doesn’t explode. It takes almost 2000°C before Tantalum metal will ignite. Okay, so if Tantalum doesn’t explode what is ddawaele seeing? It’s the cathode material, Manganese Dioxide, (MnO2) that is exploding…

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