Re: 10 amps to drive steppers

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
-----Original Message-----
From: Mo <mo@...>
To: CAD_CAM_EDM_DRO@onelist.com <CAD_CAM_EDM_DRO@onelist.com>
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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