From: S. Weir (email@example.com)
Date: Wed Oct 27 1999 - 18:28:30 PDT
This is directly addressed in Mark Montrose's book "EMC and the Printed
Circuit Board". He strongly agrees with your position for both ESD and EMI
Multiple point grounding can present a safety challenge in big boxes, as it
can cause frame electrification should the power return open for some
reason. But for EMI / ESD, I haven't seen anyone present a good
theoretical argument against multipoint grounding.
At 04:46 PM 10/27/1999 -0700, you wrote:
>From: Denomme, Paul S. [mailto:Paul.Denomme@viasystems.com]
> > Regarding comment 2, he was stating that grounding in
> > multiple locations is a bad idea. This can create some
> > ground loops within the chassis. There will be some type
> > of potential difference from one chassis connection
> > point to another and this will create some current
> > in the chassis. This is very bad from an EMI perspective.
> > He believes one Solid connection to the ground plane is sufficient.
> > I would like to hear a take from an EMI person.
>Well, personally I'd like to see some measured
>results from testing that prove this opinion.
>I've used multiple point grounding in real system
>design with great success for not only EMI but
>for ESD robustness. The fact that I instituted
>multiple point grounding from a former design
>single point grounding that had sufficient problems
>to warrant a redesign and that such redesign worked
>was proof enough for me.
>In some instances, single point grounding is impossible.
>In other instances, single point might be preferable.
>Single and multiple point grounding have their place
>under certain circumstances, but not as an all out
>general rule. - Doug
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