Re: servo amps, power supplies; addl endearments

Well Said.

I think the primary need for an *ISOLATION TRANSFORMER* in this servo
system is to keep the servo power supply from being a "HOT CHASSIS" type
of power supply. We might also want to keep the PWM switching frequency
(20Khz) out of the mains. I WON'T suggest to disregard their "isolation
transformer" specification; but what I really think they mean is a
standard power transformer (no connections between primary and
secondary, NOT an auto transformer). The similar input and output
voltages may suggest what is called an "isolation transformer", instead
of what is often called a step-down transformer. Now if we were in a
MEDICAL situation, They REALLY mean an ISOLATION transformer! Triple
shielded, hi-pot insulation, the works. Stuff that connects to a
patient... GOTTA be careful! I recall my then-company setting up a
PDP-8 computer system for a Radiation Therapy treatment planning
computer system in L.A. *NO* contact to the patient, and we had to buy
a special $300 ('77 dollars) isolation transformer, and plug the whole
computer and display system into it.

Please do consult the manufacture (Baldor) if you are still in doubt
about what is suitable (check the spec. for the transformer).

Alan (KM6VV)

Gregg Wood wrote:

>
> Can you explain an isolation transformer?
> http://www.smpstech.com/qa/qa0002.htm
>
> ----- Original Message -----
> From: Ian Wright <Ian@...>
> To: <CAD_CAM_EDM_DRO@egroups.com>
> Sent: Thursday, November 09, 2000 2:46 PM
> Subject: Re: [CAD_CAM_EDM_DRO] servo amps, power supplies; addl endearments
>
> > Hi,
> >
> > I may be a simple 'ol country guy but I was fairly sure that ANY
> > transformer - other than an Autotransformer - was an isolating
> transformer.
> > An Autotransformer definitely isn't as it has only one winding with
> > different tappings for the different voltages but any other transformer
> > which has separate windings for the primary and secondary provides
> > isolation. Where a transformer is used in the middle of a circuit as in
> > audio amplifiers etc., one end of each winding may be connected together
> on
> > the circuit board to give ground continuity but the transformer itself
> will
> > have isolated windings. The way to check is to put an Ohmmeter (multimeter
> > set to resistance scale) across the transformer's terminations - you
> should
> > get low readings across the primary and secondary windings and infinity
> > between the windings.
> >
> > Ian
> > --
> > Ian W. Wright
> > Sheffield UK
> > www.iw63.freeserve.co.uk
> > ----- Original Message -----
> > From: "Jon Elson" <jmelson@...>
> >
> > > Well, there it is! You need an external transformer to provide the
> > > AC input. The rectifier and cap are there, but no transformer!
> > >
> > > > Before doing that, however, I'd like to find out what an
> > > > isolation transformer is.
> > >