Re: Stepper power supplies, unregulated

Hi,

A 40,000uF cap charged to 100VDC with 10K ohms in parallel would read
36VDC after 400 seconds, 13VDC after 800 seconds and finally 5VDC
after 1,200 seconds.

Mariss

--- In CAD_CAM_EDM_DRO@egroups.com, ballendo@y... wrote:
> Mariss,
>
> Your answer is precisely WHY I didn't "publish" a formula.
> As I said, the reason for the "bleed" resistor is to meet a safety
> standard of a certain voltage(or less) in a certain time frame
(about
> 1/2 minute). NOT to "fully discharge" the cap! The 10k value DOES
> this, in my application...
>
> The drives ARE still connected at power off and modify the results
> over a simple R/C equation. That is why I suggested an empirical
(try
> it and see) approach.
>
> Hope this helps.
>
> Ballendo
>
>
> >A 10K resistor really does not make much of a difference. The RC
> >time constant would be 10,000 times .04, or 400 seconds. 3 time
> >constants would be considered discharged (5% of original voltage)
> >for a total time of 1,200 seconds. That is 20 minutes.
> >Mariss