Re: [CAD_CAM_EDM_DRO] What size capacitor should I use?

Rick,

Mariss has a formula that is conservative, and WORKS:

C=80000 x I/E where C is in microFarads, I is in Amps, and E is in Volts

So in your case, I would look at 80000*12/70 or 13714µF and round up to the
next highest value with a voltage rating of at least 100V

I found a capacitor at :
<http://www.surplussales.com/Capacitors/Electrolytics/10000uF-300000uF.html>

and I see they have a 15,000µF at 200V which would be satisfactory for your
purposes (Usual disclaimer).
Just trying to give you an idea of what is available and there are many
other sources out there.
It will not hurt to go higher in capacity or voltage, but NEVER go lower on
your voltage rating. ONE rule of thumb is to use a voltage rating at least
100% higher than your working voltage. Many will cheat on this rule and not
have any problems, but if rated to low, you are looking at an explosion:{(

Hope this helps,



At 07:24 AM 1/26/2005, you wrote:

>The supply once rectified will put out 70 volts, 12 amps. Can anyone
>tell me what the caps should be rated at? This assumes bipolar
>stepper operation at the above voltage that may would seldom draw
>close to the 12 amp limit.
>
>Thanks in advance,
>
>Rick L.
>

Bubba

OLDER THAN DIRT
Country Bubba
(Actually the inventor of Country and Bubba)
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LaGrange, GA

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