construction of ac and dc capacitors

[spindown]

Is there a difference in the construction of a conventional
capacitor used in dc circuits and those used with ac motors?
Thanks Paul

[Bob Scott]

AC caps are high voltage, non-polarised, and should have low ESR (Equivalent Series Resistance). That is just off the top of my head.

But I'm just your regular Tom, Dick, or Harry. For lots more information straight from the horse's mouth, take a look at Kemet's technical papers:

http://www.kemet.com/kemet/web/homepage ... l%20papers

I bet there is a plethora of information at other manufacturers' sites too. I bet everything you ever wanted to know about caps is out there somewhere. Check out "capacitor" in Wikipedia. I was drawn to some of the other related highlighted items like:

capacitor plague - http://en.wikipedia.org/wiki/Capacitor_plague
railguns - http://en.wikipedia.org/wiki/Railgun
memristor - http://en.wikipedia.org/wiki/Memristor

Bob

[haklesup]

There sure is a difference. First in basic types for example ceramic caps are always non polarized and tantalum or electrolytics are generally polarized. If you come across a non polarized electrolytic, its actually 2 caps in one package manufactured in a symmetrical back to back type of fashon. Other manufacturing technologies result in polarized or non polarized caps. In most cases it has a lot to do with the insulator and conductor and their configuration and physical properties. You'll have to research a bit more deeply to find the reason and manufacturing diagram for each type.