400 Hz

[Carlos E Murillo-Sanchez]

Dr. Erik Baigar via cctalk wrote:
>> I've heard that.  But why?  It's not like the electronics we're 
>> talking about actually runs on AC.
>
> (a) Input filters often contain caps...
> https://uk.tdk-lambda.com/content/faq/130796117766108286_FilterFAQ_how%20Image%201.jpg 
>
> With 50Hz or 60Hz they create a little current which does not hurt. 
> Applying a square wave of 15kHz has harmonics up to 100kHz and more.
> That means, that the current in these is more than 100 times bigger - 
> BAM!
Additionally, output devices with really fast switching times can 
trigger reflections back from the load, and these can potentially expose 
these devices to very high reflected voltages, which will trigger their 
breakdown.  I've seen it happen in oil field equipment, with IGBTs.

Carlos.