As convenor of SC77B WG11 which is responsible for the revision of this
document AND as a manufacturer of simulators and coupler/decouplers, we
(both the WG members and my company) have investigated a number of ways of
dealing with coupling to high speed data and telecom lines.
The problem is threefold:
1. You need enough back impedance in the line to support the voltage surge
to be delivered to the load.
2. The back filtering must be adaquate to prevent any significant surge
energy from being delivered back to the auxillary equipment (the source of
the data).
3. The loading on the line from coupling (capacitance) and the impedance of
the line from filtering, must be low enough that the data is not reduced to
the point where it is unusable.
To date, no one has offered a design that will work for data rates of more
than about 100kHz. We and other manufacturers have such designs and they are
available commercially.
The current recommendation for high speed I/O and data lines is to take a
leaf from FCC, CCITT (now ITU), and Bellcore standards which test as
follows:
With the data/telecom line connected, determine that the port is working
properly
Remove the data/telecom line, surge the input.
Replace the data/telecom line and determine that the port is still
functional.
If anyone out there has a better recommendation, please let me have it ASAP.
Our next meeting is in Berlin in May and we must have a CD of the next
revision as a result of that meeting. We'll consider any design that is
submitted.
Best Regards,
Michael Hopkins
Convenor IEC SC77B WG11
[email protected]
----- Original Message -----
From: "John Woodgate" <[email protected]>
To: <[email protected]>
Sent: Wednesday, March 27, 2002 2:58 PM
Subject: Re: EMC test set-up for device with ethernet connection
>
> I read in !emc-pstc that [email protected] wrote (in <846BF526A205F8
> 4BA2B6045BBF7E9A6A01F13FB2@flbocexu05>) about 'EMC test set-up for
> device with ethernet connection', on Wed, 27 Mar 2002:
> >We have recommended to the manufacturer of the surge generator
> >that the IEC/CENELEC techincal committee include this test method in a
> >revision of the standard.
>
> You should make the same proposal to IEC SC77B through your national
> committee of the IEC. The equipment manufacturer may be reluctant to
> support a proposal that requires modification to his product.
> --
> Regards, John Woodgate, OOO - Own Opinions Only.
http://www.jmwa.demon.co.uk
> Interested in professional sound reinforcement and distribution? Then go
to
> http://www.isce.org.uk
> PLEASE do NOT copy news posts to me by E-MAIL!
>
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