Re: Power Factor Correction

To: tesla-at-pupman-dot-com
Subject: Re: Power Factor Correction
From: "Ken Donnell" <bigken-at-a.crl-dot-com> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
Date: Fri, 30 Jul 1999 05:10:53 -0600
Approved: twftesla-at-uswest-dot-net
Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

I'd check the AC current rating on the D-K caps and see if it's high
enough. Then I'd run them under a shatter cover in case they decide to
explode. The motor caps seem to me to be a better choice, though, because
they are made for the job. As long as they are run caps as opposed to
starting caps (lower heat dissipation, that is, lower Equivalent Series
Resistance or ESR), any manufacturer should be OK.

Ken

----------
> From: Tesla List <tesla-at-pupman-dot-com>
> Original Poster: Terry Fritz <twftesla-at-uswest-dot-net>
> 
> Hi All,
> 
> 	I was playing with computer models all day today and got interested in
> power factor correction caps.  I found I can get my coil down to about
8.2
> amps RMS input by adding 140uF of capacitance across the neon input. 
This
> will reduce the VA input from around 1550 to about 1000.  Digi-Key sells
> little 20uf AC caps for fairly cheap and using a bunch of these would
allow
> for easy adjustment of the value.  Reducing the input current would take
> the load off the control box parts and let me run the coil and gap motor
> off the 15 amp power strip (the strip breaker likes to blow otherwise). 
I
> did have a few questions for those that know about such things.
> 
> I notice that same AC capacitors (like ones from GE) are significantly
more
> expensive than others.  They are all full-time motor run caps made with
> polypropylene (I bet some or oil filled) but I was wondering why the
price
> difference for what appears to be the same cap?  the 60UuF were $15 for
one
> manufacturer and $65 for GE...  Digi-Key sells only 20uF but the price is
> faily good for the value I need even if I do need to use 7 of them...
> 
> Are there any hidden things I should know about like inrush currents, cap
> explosions, openload or short problems?  I ran some models with various
> faults and all looked very good but...
> 
> Is there any easy way to calculate the cap value for a real coil with all
> of it's dynamics?  MicroSim could easily find the value but I was
wondering
> if there was an easy equation or something like that.  The value is not
> real critical.
> 
> Cheers,
> 
> 	Terry
> 
>