Re: e-stop sceme

Mike,

I'd put a 4 pole relay with contacts rated at about 5A 120VAC on the
primary of the transformer. As this is a personal, not production
design I'd look for one that can be socketed. (I've changed out too
many relays where you had to be a contortionist to de-solder the old
and re-solder a new one in.) I chose 5A as the current rating so
that I could standardize across several different versions. A 30V
10A transformer requires about 4 amps at the primary and yields about
a 40VDC output while a 50V 5 Amp requires about 2.5 Amps and yields
an output of about 68 VDC. (Someone will pick me up on this, so just
let me say that the DC values are after rectification and
filtering.) This gives me the flexibility to add transformers to up
the output to 20 Amps at the rated voltages - plenty for 3 Gecko
stepper motor drivers running flat out. I wouldn't go over 50VAC
outputs on the secondary as this gives the Geckos some breathing
room. This is a personal preference as I will have to pay for the
replacement of any Gecko that I kill. If I need more axes - I'll add
a second power supply - they can share the EPO circuits.

Tony

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "zbushz" <mbush@l...> wrote:
> Sound good to me Tony, Do you have any idea what sort of relay you
> would need to control 70v dc 20 amp.
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Antonius J.M. Groothuizen"
> <agroot@s...> wrote:
> > Mike,
> >
> > I'm thinking along the lines of:
> > - separate 12V power supply for EPO / E-Stop
> > - series connected EPO switch chain (one on PS / driver box)
> > - primary power of main TX removed by de-energized relay
> > - capacitors on secondary discharged by Mariss' circuit (in
files)
> > - drives disabled
> > - control lines (step / dir) disabled
> > - EPO signal (active low) available for processor
> >
> > Let's both come up with a design, and let this forum rip 'em
apart
> > as we both will have different ideas. We can then merge our
efforts
> > into a single project for the files section. I'm using the G201
> > drivers, so much the better if you are using a different set as
we'll
> > have two examples.
> >
> > What do you think?
> >
> > Tony
> >
> > --- In CAD_CAM_EDM_DRO@yahoogroups.com, "zbushz" <mbush@l...>
wrote:
> > > OK. I have Geckos and Bob Campbells breakout board.I have a
seperate
> > > 50v power suppy. Now I am starting to put the whole thing
together.
> > > The first steps are powering everything up. I think the second
step
> > > should be arrainging for e-stop. I would like a normaly closed
red
> > > mushroom, that when opened will remove power to everything. If
I put
> > > relays on the power to the board and the incomeing dc power,
would
> > > that be enough. Is it good pratice to power down this way. Do I
need
> > > to be concerned with voltage generated by the motors coming to
a
> > stop.
> > > I would expect to use this button rutinely to put the machine
in a
> > > safe state for tool and part changes. Any advice will be
appreciated
> > > take care
> > > Mike Bush