Hi Group, I watched this interesting thread and noticed that none of you recalled the susceptibility of the system.
We had severe problems with susceptibility of computers with Ethernet coax connection. As a matter of fact did not find any computer meeting the requirements for industrial environment of the 61000-4-4 (burst). They all failed at levels of a couple of hundred volts. Using capacitor coupled BNCs helps a bit. We simply bonded the shield to ground. I have to notice, that all computers attached to the network were in the same floor of the same building. Best regards George ************************************************************** * Dr. Georg M. Dancau * HAUNI MASCHINENBAU AG * * [email protected] * Manager Product Development * * TEL: +49 40 7250 2102 * K.A.Koerber Chaussee 8..32 * * FAX: +49 40 7250 3801 * 21033 Hamburg, Germany * ************************************************************** * home: Tel: +49 4122 99453 * Hauptstr. 60a * * Fax: +49 4122 99454 * 25492 Heist, Germany * * Cellular: +49 175 5805280* * ************************************************************** From: "Ken Javor" <[email protected]> To: "Stone, Richard A (Richard)" <[email protected]>; "'Knighten, Jim L'" <[email protected]>; <[email protected]> Sent: Wednesday, March 05, 2003 11:10 PM Subject: Re: Ethernet coax connection > > Thanks to all who answered in MINUTES assisting an EMI troubleshoot on > something that is of great national value. > > This forum is a tremendous resource! > > > > > on 3/5/03 4:46 PM, Stone, Richard A (Richard) at [email protected] wrote: > > > we've had good success with the > > built capacitance of 9000pf as well, > > depending on test being discussed and > > frequency, certain cap. values from the shielded > > ring of the UNgrounded ring to earth works well > > for low freq..< 30 mhz. > > Richard, > > -----Original Message----- > > From: Knighten, Jim L [mailto:[email protected]] > > Sent: Wednesday, March 05, 2003 4:12 PM > > To: Ken Javor; [email protected] > > Subject: RE: Ethernet coax connection > > > > > > > > Ken, > > > > It is a potential shock hazard if the coax run is long and runs from > > building to building (for instance) where the ground potentials may be > > different in the different buildings. One can develop a large potential on > > the shield of the cable, so that if you put yourself between the cable > > shield and ground you may get a strong shock. That is the reason for > > isolating the shield from more than one direct connection to ground. It is > > a real issue. The result for EMI is, as you have noted, the creation of an > > egregious EMI offender. I have used the chassis mounted BNC connectors with > > built-in capacitors successfully. > > > > Jim > > > > > > Jim Knighten, Ph.D. > > Teradata, a Division of NCR http://www.ncr.com > > 17095 Via Del Campo > > San Diego, CA 92127 > > USA > > Tel: 858-485-2537 > > Fax: 858-485-3788 > > [email protected] > > > > -----Original Message----- > > From: Ken Javor [mailto:[email protected]] > > Sent: Wednesday, March 05, 2003 12:58 PM > > To: Knighten, Jim L; [email protected] > > Subject: Re: Ethernet coax connection > > > > Assume complete ignorance on my part. What is the safety concern? > > > > > > on 3/5/03 3:50 PM, Knighten, Jim L at [email protected] wrote: > > > >> Ken, > >> > >> Safety considerations are the reason for the spec requirement. You are > >> allowed to ground the shield at one point. > >> > >> Try using a BNC coax connector with a built-in capacitor to ground. That > >> gives you an AC connection to ground and is often quite effective. These > >> are off-the-shelf parts. > >> > >> Jim > >> > >> > >> Jim Knighten, Ph.D. > >> Teradata, a Division of NCR http://www.ncr.com > >> 17095 Via Del Campo > >> San Diego, CA 92127 > >> USA > >> Tel: 858-485-2537 > >> Fax: 858-485-3788 > >> [email protected] > >> > >> -----Original Message----- > >> From: Ken Javor [mailto:[email protected]] > >> Sent: Wednesday, March 05, 2003 12:38 PM > >> To: [email protected] > >> Subject: Ethernet coax connection > >> > >> > >> Question for list members: > >> > >> Background: I am troubleshooting a complex integration of military > > hardware > >> and COTS. One COTS piece of equipment has an RG-58 coaxial connection, > > but > >> the coax connector is an isolated feedthrough bnc. From a radiated > >> emissions point-of-view, that is hurting us. One of the engineers here > > said > >> that is part of the spec - Ethernet shields are not supposed to be chassis > >> grounded. > >> > >> Question: Can someone please explain the reason for that, and how this is > >> usually handled to minimize radiated emissions? > >> > >> Thank you. > >> > >> Ken Javor > >> EMC Compliance > >> Huntsville, Alabama > >> 256/650-5261 > >> > >> > >> > >> ------------------------------------------- > >> This message is from the IEEE EMC Society Product Safety > >> Technical Committee emc-pstc discussion list. > >> > >> Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > >> > >> To cancel your subscription, send mail to: > >> [email protected] > >> with the single line: > >> unsubscribe emc-pstc > >> > >> For help, send mail to the list administrators: > >> Ron Pickard: [email protected] > >> Dave Heald: [email protected] > >> > >> For policy questions, send mail to: > >> Richard Nute: [email protected] > >> Jim Bacher: [email protected] > >> > >> Archive is being moved, we will announce when it is back on-line. > >> All emc-pstc postings are archived and searchable on the web at: > >> http://www.ieeecommunities.org/emc-pstc > >> > > -- > > Ken Javor > EMC Compliance > Huntsville, Alabama > 256/650-5261 > > > > ------------------------------------------- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > To cancel your subscription, send mail to: > [email protected] > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Ron Pickard: [email protected] > Dave Heald: [email protected] > > For policy questions, send mail to: > Richard Nute: [email protected] > Jim Bacher: [email protected] > > Archive is being moved, we will announce when it is back on-line. > All emc-pstc postings are archived and searchable on the web at: > http://www.ieeecommunities.org/emc-pstc This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
