[SI-LIST] Re: Book - (Chassis - signal ground)
- From: "Paul Hamilton" <paulh@xxxxxxxxxxxx>
- To: <si-list@xxxxxxxxxxxxx>
- Date: Fri, 22 Jun 2001 14:36:14 +0800
An issue to consider might be ESD (EMC electrostatic discharge)
susceptibility. A complex system could present several current paths for ESD
strikes which may be difficult to manage. Isolating signal ground from
chassis (and also ensuring that signal ground cannot take an ESD strike)
would be one way to guard against ESD hassles. I've had grief with a simple
clam style enclosure about the size of a telephone - and chassis was
isolated from signal ground except at one point.
Paul Hamilton.
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Alex Horvath
Sent: Friday, 22 June 2001 9:34
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Book
Someone recommended Henry Ott's book "noise reduction techniques in
Electronic Systems" and I have this book and didn't find it very useful for
chassis grounding (it's very old). He actually recommends separating chassis
and digital ground. I think this is based on how systems in the past often
had shielded cables going from one chassis to another. Often the ground
potentials are different in those systems and large currents can flow in the
shield and thus in the chassis. The large currents in the chassis can cause
noise and or the ground reference to change if the digital ground is part of
the chassis. Most telecomm systems I work with today don't have any shielded
cables or for that matter any ground connections between chassis. Also, all
of the telecom companies I have worked at have tied digital ground to the
chassis (also PC's are made this way).
snip ..
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