RE: What kind of PFC Capacitors

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Gary.Lau-at-hp-dot-com>

If you apply 120VAC across the cap's terminals, a good "run" cap will stay
cool.  If it was a "start" cap (which is bad), it will get warm within
about a minute, and is likely to explode, so please consider a blast shield...

Regards, Gary Lau
MA, USA

 -----Original Message-----
From: 	Tesla list [mailto:tesla-at-pupman-dot-com] 
Sent:	Sunday, July 14, 2002 12:35 AM
To:	tesla-at-pupman-dot-com
Subject:	Re: What kind of PFC Capacitors

Original poster: "Daniel McCauley by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <dhmccauley-at-spacecatlighting-dot-com>

Thanks for the info.  Anyways, I have a lot of caps at work which look
similar to Motor Run caps.  How would I know if they are acceptable for
use in this application???

Thanks again.
dan




> Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>
>
> Hi Dan,
>
> There are two kinds of motor caps.  "motor RUN" and "motor START".  You
> need to get the motor "RUN" types that are made to run continuouosly.
> Motor start caps will overheat and explode in about a minute.  Motor run
> caps are larger and lower value than the start types.  The run caps change
> the phase to the motor windings as it is running where the start types are
> for very high current but very short time starting duty.  The run types
are
> usually oil filled poly for handling current contuously.  Note that motor
> run caps are very expensive new, but dirt cheap surplus.
>
> Cpfc = ( Vo x Io ) / ( 2 x pi x f x Vi^2 )
>
> Where
> Cpfc = Power factor cap value in Farads
> Vo = Rated NST output voltage in volts
> Io = Rated NST output current in amps
> pi = 3.14159...
> f = AC line frequency (50 or 60Hz)
> Vi = AC input voltage (120 VAC)
>
> The exact value is not important here.  It is best not to go too much
> higher.  Lower is better if you have a choice.  Some more precise values
> for static gap systems are given in the tables at:
>
> http://hot-streamer-dot-com/TeslaCoils/Misc/NSTStudy/NSTStudy.htm
>
> But unlike primary cap values, you can be way off with little harm.
>
> Cheers,
>
> Terry
>
>
>
>
> At 08:29 AM 7/13/2002 -0400, you wrote:
> >
> >
> > I would like to add some PFC Caps to the input of my NST.  What kind
> >of caps are typically used for this and how do i determine the value?
Are
> >these just standard motor type capacitors?
> >
> > Thanks
> > Dan
> >
>
>
>
>
>