[TowerTalk] Polarized Electrolytic in Rotator Box?

[Jim Lux]

At 04:01 PM 6/29/2007, gdaught6 at stanford.edu wrote:
>On 29 Jun 2007 at 17:50, Clint Talmadge wrote:
>
> > I am glad this thread started. I have  a Motor Start Capacitor 
> ready to be installed at the base of my tower which is marked 
> 130-156 MFD 330VAC . How can I tell if it is polarized or not? 
> There are no + or - marks on the terminals and I assumed (I know, I 
> know) that it would work.
>
>If the capacitor is rated for AC, (330VAC) then it shouldn't have a
>polarity marked, should it?  Maybe we get confused because AC rated
>capacitors CAN be used on DC (with a voltage rating about 3x the AC
>rated voltage.)  But if it's AC rated, then using it on AC is what's
>expected!  Am I missing something?


Nope.. if you use it on DC, though, you'll find it's a pretty lossy 
cap (at least motor start caps are).  In that application (which is 
very price sensitive) they don't go to huge efforts to produce a high 
quality cap (hence the 130-156 uF rating).  As long as it doesn't 
explode in the normal usage, they consider it "good enough".