Re: [CAD_CAM_EDM_DRO] Re: bridgeport series 1 retrofit

Guys -
Couldn't two diodes be placed in parallel - one to drop the voltage he
wants to drop and the other ('pointing' in the other direction) to prevent
the buildup you speak of ?

Myron Cherry

----- Original Message -----
From: "bull2003winkle" <bull2003winkle@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Saturday, January 10, 2004 12:29 PM
Subject: [CAD_CAM_EDM_DRO] Re: bridgeport series 1 retrofit


> --- In CAD_CAM_EDM_DRO@yahoogroups.com, Jon Elson <elson@p...> wrote:
> >
> >
> > Bob Japundza wrote:
> >
> > >Guys, thanks for the responses. Sounds like having a closed loop
> > >feedback system the way I described might be not worth the effort.
> > >But I do plan on installing the DRO anyway. On the power supply I
> > >may just add some diodes in to get the voltage drop.
> > >
> > You can't do that. The diodes prevent any energy returned from the
> > motors to the drives from being stored safely. The small capacitance
> > in the drives can't contain much energy, so the voltage quickly rises
> > to damaging levels. When large motors are decelerated, they can
> > return energy to the drive.
> >
> > Jon
>
> Jon is right about the diodes. If you want to drop a small voltage
> there's a better way to do it. Put a very small value resistor in
> series between the transformer and the bridge rectifier. It has the
> added benefit of reducing the peak current in the bridge and
> capacitor. Even very low values will dissipate a lot of power.
>
> Ken
>
>
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