Re: 10 amps to drive steppers

Mo or Jon,

Would love to have a schematic of this setup and would definitely be happy
to get it posted.

Regarding disconnecting a motor on a Camtronics board while it is powered
and running, I inadvertently did this once and the board survived with no
harmful side effects. I may have been lucky as I only had some small NEMA 23
motors set up at about 1 amp.

Tim
[Denver, CO]

> -----Original Message-----
> From: Mo [mailto:mo@...]
> Sent: Monday, June 14, 1999 7:50 PM
> To: CAD_CAM_EDM_DRO@onelist.com
> Subject: Re: [CAD_CAM_EDM_DRO] 10 amps to drive steppers
>
>
> From: "Mo" <mo@...>
>
>
> > From: Jon Elson <jmelson@...>
> > A properly designed stepper driver shouldn't be troubled by operating
> > with no load. Unplugging or plugging in the motor while the driver is
> > active could cause some arcing that might cause damage, but just running
> > the driver with no motor connected shouldn't be a problem.
>
> Jon, unfortunately both types of board I have here warn that this is a
> certainty
> and I believe the Camtronics boards are the same. I have inadvertantly
> killed one that way.
> It must be in the design, as you say. Where a manufacurer warn
> specifically
> that their design
> will be seriously damaged by this - it is good to take the precaution.
>
>
>
>
>
> > Here's what I did, although it is on a servo system, but the
> problems are
> > similar. The E-stop signal on my system releases a pair of relays (one
> > a signal size, the other a power contactor). When these relays are
> > released, they connect a power resistor to the servo amps power
> > input, discharging the power supplies. When the relays are engaged,
> > first the signal relay closes, connecting the same power resistor in
> > series with the DC supply and the servo amps. Another contact on
> > this relay connects power through to a time delay circuit. After
> > a 1 second delay, giving time for the resistor to ramp up the
> > voltage in the servo amps, the power contactor closes, delivering direct
> > power to the servo amps. When this relay closes, it also connects
> > the enable input to the servo amps to +12, turning them on.
> > This gets rid of all the high DV/DT transients when powering things
> > up and down, and makes sure that whenever there is a fault, everything
> > is powered down in a controlled manner.
>
> Perfect power up and enable sequencing. The power bleed resistors are the
> absolute
> minimum needed for those that do not have a similar set-up and
> are still in
> the process of playing around with their assembly.
> Jon do you have a schematic for that set-up - if not I could
> knock something
> up and put it on Tim's site for members who would like to go that route.
>
>
> Mo
>
>
>
>
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