RE: [CAD_CAM_EDM_DRO] Re: another transformer question

For what it's worth, Jameco (www.jameco.com) has 470uf 100v caps for
US$1.89.

I know what I would do.

Regards,
JJ

Be Kind, Be Careful, Be Yourself

> -----Original Message-----
> From: caudlet [mailto:tom@...]
> Sent: Sunday, August 11, 2002 1:24 PM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: [CAD_CAM_EDM_DRO] Re: another transformer question
>
>
> <snip> for 48VDC so should just make it under 50V, but the
> measurement says
> > 60VDC, so should I risk it and go ahead to use the same capacitor,
> > even if only temporary? What happens when one exceed the rated
> > voltage of a capacitor?
> >
> > Thanks
> >
> >
>
> In the short term normally nothing happens. If the overvoltage lasts
> too long or is way over the limit of the working voltage things can
> get interesting in a hurry. The insulation layer starts to break
> down and the cap starts to draw excessive current which results in a
> rapid build up in internal heat and the electrolyte starts to turn to
> steam. Usually the result in larger caps is a hissing noise with
> gook flowing out of the cap. The cap can explode (smaller ones go
> off like firecrackers) but the real danger is to down stream
> components. If you loose the filter cap the electronics running off
> of it are essentially running off half wave AC at 120HZ...not kind to
> components expecting nice smooth DC!
>
> A lot of transformers are designed and rated at close to full load to
> account for losses in the windings and other magnetive things, so a
> 36VAC unit might go to 40VAC lightly loaded but 45Volts sounds
> excessive. Your two 12VDC fans in series should really be spinning
> at 60VDC! The resistor in series will reduce that some but you may
> have to increase the value to keep the voltage across the fans 24VDC.
>
>
>
>
> Addresses:
> FAQ: http://www.ktmarketing.com/faq.html
> FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
>
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>

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