RE: [CAD_CAM_EDM_DRO] Re: Here's my proposed power supply setup.

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@...]
> Sent: Friday, August 16, 2002 12:46 PM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> 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.
>
>
>
>
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