Re: Motor run caps again - Use a Cheap 3 Phase Cap!

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

Original poster: "Bert Hickman by way of Terry Fritz <twftesla-at-uswest-dot-net>" <bert.hickman-at-aquila-dot-net>

Ed,

This is your lucky day! 

It turns out that USA Manufacturing has a 3-Phase PFC cap that's rated for
5 KVAR at 240 VAC at 60 Hz for $1.25 (yep, that IS the correct price!). You
can go to their site at:
http://www.usamfg-dot-net/

You want to select "Access Our Actual Current Inventory", then search by
Item Number, and look for item #86045

You'll find that this a metalized polypropylene PFC cap made by Aerovox,
Model AMP0005035B, about 4.5" x 2.75" x 8.5". It has 5 terminals, and comes
with quick connect terminals and bleeder resistors.  Refer to the ASCII art
drawing below. Two of the terminals (T1 and T3) are for Loss of KVAR
indicator lights (leave these disconnected), while the other are the actual
three phase terminals (T2, T4, and T5) used for Power Factor Correction.
Internally, the capacitor has 3 equally sized capacitors connected in a
delta configuration between terminals T2, T4, and T5. 

For single phase use, you can simply pick any two of the three phase
terminals. 

                T4   T5
                O     O                    

           T1     T2     T3
            O      O      O

Since this is a 5 KVAR at 240 VAC and 60 Hz, the total capacitance (made up
of the sum of the three individual internal caps) will be:

   C = 1000*KVAR/(2*Pi*F*(V^2)
 where:
   C = uF
   KVAR = KiloVolt-Amperes-Reactive rating
   F = 60 Hz
   V = line-line voltage
 solving:
   C (total) =  230 uF  total
 And,
   C (individual) = 230/3 = 76.8 uF
 
Now, if you connect any pair of the phase leads to your circuit, you'll
have about 77 uF in parallel with 154 uF, or an effective capacitance of
about 115 uF at 240 VAC. Not bad for $1.25 is it... :^)

Hope this helped!

-- Bert --     
-- 
Bert Hickman
Stoneridge Engineering
Email:    bert.hickman-at-aquila-dot-net
Web Site: http://www.teslamania-dot-com


Tesla list wrote:
> 
> Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>"
<Esondrmn-at-aol-dot-com>
> 
> I found a good motor run cap to use for my sync gap phase control circuit at
> H & R (Herbach & Rademan).  135 ufd for $10.95 - ordered it and was then
> notified by them that they are out of stock.  Does anyone know of another
> source for one of these?  I am looking for one capacitor that is at least 100
> ufd.
> 
> Thanks, Ed Sonderman