Re: Here's my proposed power supply setup.

Actually you can "over fuse" things. All you need is a fuse in the
primary side of the xformer. Any fault on the secondary side would
drive up the primary's magnetizing current where the 115VAC fuse
wuold blow.

Mariss

--- In CAD_CAM_EDM_DRO@y..., "JJ" <jj5412@e...> wrote:
> The chopper drivers wear engineer's boots and leather jackets.
>
> Oh, wait, okay. The chopper drivers reduce the current requirment
from
> the powert supply since they aren't "on" all the time.
>
> As far as fusing, you need a fuse on the primary (120v/230v) side. I
> believe for you this would be:
> 50 / 120 * 14 = 5.8, I would round up to 7, 8 or so. Oh yeah, must
be a
> 250v fuse.
>
> For the secondary (50v) side, you need a fuse right off the
secondary,
> before it goes into the rectifier, probably 15 or 20 amps. You
want a
> 250v fuse here too.
>
> As far as fusing the supply to each drive, have at it.
>
> When a fuse blows on the supply to the drive, it's the same as
turning
> the power supply off. The fields in the motors collapse and send
current
> into the drives, but no more than when the phase turns off when
another
> turns on. The problem with unplugging is there isn't a clean break,
the
> fields build and collapse rapidly, sending a lot more current into
the
> drive than normal, not to mention high frequencies due to arcing.
>
> That's my take on it. Standard disclaimers apply :-)
>
> Regards,
> JJ
>
> Be Kind, Be Careful, Be Yourself
>
>
>
> > -----Original Message-----
> > From: mayfieldtm [mailto:mayfiet@i...]
> > Sent: Friday, August 16, 2002 12:46 PM
> > To: CAD_CAM_EDM_DRO@y...
> > Subject: [CAD_CAM_EDM_DRO] Re: Here's my proposed power supply
setup.
> >
> >
> > --- In CAD_CAM_EDM_DRO@y..., "mariss92705" <mariss92705@y...>
wrote:
> > > Adding all the currents gives you 13.5A. 2/3 of that is 9A.
> >
> > OK! Now I'm confused about motor current vs supply current.
> >
> > I have always assumed that the name plate current rating is for
EACH
> > winding.
> >
> > Suppose my 8 lead motor has "1 Amp" on the name plate.
> > I wire these in parallel. So now it's a 4 lead motor to be used
with
> > a Gecko 201 H-Bridge Driver.
> > Would that not be a total of 2.67 amper draw from the power
supply?
> > (4 amps times 2/3)
> > And if so, then I should set the Driver to 4 Amps?
> >
> > In which case Lloyds' power supply should be at least 18 Ampers.
> > (Assuming all motors wired in parallel.)
> >
> > I know you are correct, what's wrong with my thinking?
> >
> > Is the name plate rating a total for all windings? That would
make no
> > sense to me at all.
> >
> > Also... Filter Caps and their sizes.
> >
> > I have always way way way over rated the Capacitance of Filter
Caps
> > in brute force power supplies (like 5 to 10 times).
> > Other than cost, physical size and inrush currents, is there a
> > problem with doing this?
> > I guess I've aimed for less ripple, less heating and better
handling
> > of back emf from the loads.
> >
> > Tom M.
> >
> >
> >
> >
> > Addresses:
> > FAQ: http://www.ktmarketing.com/faq.html
> > FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
> >
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> > to reach it if you have trouble.
> > http://www.metalworking.com/news_servers.html
> >
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