Re: Gecko E-Stop recommended configuration

Tom,

The cap can be 100V. Its purpose is to assist the main filter cap in
the power supply because the switch contact resistance decouples the
filter cap from the drive.

An important modification should be made that I overlooked in the e-
stop switch circuit. A power resistor of 0.1 ohm per volt of power
supply voltage should be placed in the ground leg of the switch. For
instance if your power supply voltage is 68VDC, use a 6.8 ohm
resistor. This will limit the dynamic break current to 10A. Wattage
depends on the mass being decelerated during an e-stop, 10W is a good
starting point.

Regards to the circuit you sent. I will contact you off list about
it. It has some problems.

Mariss

--- In CAD_CAM_EDM_DRO@y..., "Tom Eldredge" <harmonyt@r...> wrote:
> Mariss,
>
> Thank you for your help on the Estop. I guess the cap voltage
rating can be
> around 100 volts on an 80 v system?
>
> The purpose of the capacitor is to supress arcing on the contacts,
I take
> it.
>
> Did you get a chance to glance at Doug Harrison's fault circuit
that I faxed
> you?
>
> Gratefully,
>
> Tom Eldredge
> ----- Original Message -----
> From: <mariss92705@y...>
> To: <CAD_CAM_EDM_DRO@y...>
> Sent: Wednesday, June 06, 2001 5:10 PM
> Subject: [CAD_CAM_EDM_DRO] Re: Gecko E-Stop recommended
configuration
>
>
> > Tom,
> >
> > Brush DC motors are able to run without benefit of any
electronics,
> > step motors are not. Brush DC servo systems are equiped with
> > protection circuits to prevent against most runaway faults but not
> > all, such as a shorted transistor.
> >
> > The only sure fire way to stop a motor is to remove power from it.
> > The question is how.
> >
> > 1) Shut off the AC input to the supply. This is easiest on the
switch
> > and the drives but the power supply filter capacitor "hold-up"
time
> > may be a second or more.
> >
> > 2) SPDT switch in the DC supply circuit. Common to the drive's "+"
> > supply input, N.C. to the power supply "+" terminal, N.O. to the
> > drive's "-" supply. This has the benefit of dynamically breaking
the
> > motor after disconnect from the power supply. The switch contact
> > rating is higher and there must be at least a 1,000 uF capacitor
> > across the drive's power supply inputs at the drive. This is
tough on
> > the cap and switch.
> >
> > 3) For more mundane (non-emergency) faults in multiple axis setups
> > please see the "4 axis reset manager" pdf in the "files section of
> > this group.
> >
> > Hope that helps. I am writing an applications section for the
servo
> > drives. It should be finished in a few weeks. I am trying to keep
it
> > from having as many pages as Tolstoy's "War and Peace".
> >
> > Mariss
> >
> > --- In CAD_CAM_EDM_DRO@y..., "Tom Eldredge" <harmonyt@r...> wrote:
> > > Mariss, and other Gentlemen,
> > >
> > > If this has not been already covered, do we need an application
> > note on this subject?
> > >
> > > Many of us are using or are planning to use the G320, 340
drives.
> > What is the recommended proceedure for E-stopping a G320 servo
loop?
> > It is my understanding that for safety reasons, the power is to be
> > removed from the motor/drive, and IC logic is not to be depended
upon
> > to actually stop motion in an emergency situation. If so, where
> > should we put in the relay to do so, in the power line to the
amp, or
> > inside the motor/drive loop? If not, should we simply use the
> > disable input to the drive for emergencies?
> > >
> > > Thanks again,
> > >
> > > Tom Eldredge
> > >
> > >
> > >
> > > [Non-text portions of this message have been removed]
> >
> >
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