Re: [CAD_CAM_EDM_DRO] cap question

Thanks for bringing the higher voltage factor into light Jon.
I also have a trans. that will output 35V, which with your calculation,
would give me 50V, and I would be able to use the same cap. The other way
would be to use the same trans. And feed it from the "controversial"
variac, being carefull to put a hard limit on the dial. My dillema
is that I have 15 nema 34s,300inoz,3V,4A which I would
like to use on several machines, which at max 20 times rated V would be 60V.
But, I also have 4 Nema42s,6A,600oz,5V which I would like to use this driver
setup with, which may require higher V. This is also the reason for the
heavier current output of the trans. You
are probably right that I would not be running at 25A, but
I want that headroom. Also I would like to be able to get
within 80% of the gecko's rating. The Ideal is one controller for each
setup, but then I would need several cooling fans, one for each
controller, and one for my wallet...
Thanx

----- Original Message -----
From: "Jon Elson" <elson@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Monday, April 01, 2002 11:59 PM
Subject: Re: [CAD_CAM_EDM_DRO] cap question


> Mike Snodgrass wrote:
>
> > Hello, on my on-going power supply project, I am putting
> > together a 25A unit. By using a rough estimate of 1000mf
> > per A load, I need 25000mf. I have a 33000mf 60V cap. The output of my
trans is 58V.
>
> Oh, yes, I wanted to comment on this. If the output of the transformer
reads
> 58 V AC, you will get 82 Volts out of a full-wave rectifier and
capacitor-input
> filter. That will cause a problem for your caps and the Gecko drives I
think you
> will be using this with.
>
> Explanation : An AC voltmeter is calibrated to read the root-mean-square
(RMS)
> equivalent of the energy delivered to a resistive load. This will read
the same
> value as a DC voltage that produces equivalent heat in that resistor.
BUT, the
> actual peak voltage of a sine wave is 1.414 (Square root of 2) times the
RMS
> reading. The capacitor of a capacitor-input filter captures the peak
voltage,
> so you get a higher voltage than the AC RMS reading from the transformer.
> 58 x 1.414 = 82
>
> Jon
>
>
> Addresses:
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