The camtroinc controllers run just fine without a motor connected.
No damage will occcurr with the drivers if a motor is left off.
Never disconnect or connect a stepper motor while the power is on. You will
create an inductive spike which can fry the output chips.
If a stepper in connected to the power supply and the unit is shut off then
the cap will be discharged by the motor. But if you are testing the
ciircuits without a stepper connected then a resisdual charge will be held
on the the electrolytic caps.
Dan
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-----Original Message-----
From: Mo <mo@...>
To: CAD_CAM_EDM_DRO@... <CAD_CAM_EDM_DRO@...>
Date: Monday, June 14, 1999 8:02 PM
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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