Re: Power Supply Box's

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Jarrett & Heidi Johnson
<hjjohnson@...> wrote:

>
> What is the implications of building a power supply and

computer box

> together?
>
> I've been tossing around the idea of building a dedicated

power

> supply box which not only houses the power supply but has the

needed VFD,

> G100, drives and spindle control interface card [ Digispeed?] as

well as

> any other little relay's etc. In addition to this I'd like to

mount my

> computer components right into this same box, MoBo, Drives, Video

card and

> have a touch screen and industrial keyboard. Is having all of this

in 1

> control box asking for problems? Should I be segregating the

computer

> components from the rest of the power supplies and VFD [ partition

the box

> to help eliminate RF and other gremlins into the works]? I'd

beening

> thinking about just buying a bare bones kit from TigerDirect.ca

[or the

> like] and using the guts outta it, not the case [well maybe switch

out my

> old plane Jane case on my home comp. for the new one if it was

fancy].

>
> Crazy?
>
> Jarrett Johnson
>

I think you are asking for a long frustrating project. The more you
can do to separate low level logic systems and high power circuits
the better. It may work with no problem. It may reset your
computer everytime the motors get under load or it may just wait
until you have expensive project 80% done and ruin it.

Grounding/shielding for minimum RFI and EMI interference is the
subject of entire books (I know because I have one). It CAN be done
but it takes a lot of testing and understanding of how HF signals
are propagated across common connections and through the air.
Putting signals inside a cabinet helps keep them from transmitting
to the world. Put two systems into the same case actually works
against you since the crosstalk in the cabinet is greater.

We could design a switching power supply in a few hours. It then
took days to minimize the noise so the control electronics would not
pickup the PWM power spikes.

If you want to move the PC out close to the controller, consider
either having two separate metal compartments for each side. You
power supply and motor drives in one side and your computer and
breakout card in the other.

Any wire over 12" long becomes an antenna for RFI. Running them in
close proximity lets them more easily "talk" across. The inverse
square law applies to RFI where the strength of the field is 1/4 if
the distance is doubled. That is in open air. Closed insde
a "faraday shield" the calculations are much more complex