Re: Safety Critical etc - the future
I read in !emc-pstc that scottba...@aol.com wrote (in 112.710b623.29153 2...@aol.com) about 'Safety Critical etc - the future', on Sat, 3 Nov 2001: Hello John, Very condescending answer, I am aware there are other countries. It wasn't intended to be condescending, just pointing out a factor that you appeared to have not taken into account. I am also aware that there are almost no forums for Product Safety Engineers and professionals save this one we are on, worldwide, not just in the USA or the UK or Malaysia. OK, maybe we only need one. If we have more, they may come to different conclusions, magnifying confusion. Since we are so wrong having these societies and not sharing the concept, what are the professionals in the EU doing? I didn't say, or even imply, that you were wrong to have them. I just pointed out that others don't have them. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Eat mink and be dreary! --- 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
RE: EMC test table construction plans
I agree that wood and other high density materials are a problem as one approaches 1 GHz. I have data (taken in a previous life) that clearly shows the effect of a wooden table with a Formica top. This was done by placing an isotropic field sensor (ok, close to isotropic) at the center of a table and illuminating it from three meters away in a semi-anechoic chamber. Field strength was measured at each ten degrees of rotation at several frequencies up to 1 GHz. The effect at 1 GHz was in excess of 6 dB difference. The interesting part is that what appeared to be happening was low angle (below the critical angle) dielectric reflection. The signal was strongest when aligned with the corners of the rectangular table. Brent DeWitt Datex-Ohmeda Louisville, CO -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Sundstrom Michael (NMP-RD/Dallas) Sent: Friday, November 02, 2001 7:09 AM To: 'Pommerenke, David'; 'POWELL, DOUG'; EMC-PSTC (E-mail) Subject: RE: EMC test table construction plans We use a styrofoam table here at our lab, it is a round plug of styrofoam 80cm tall and 1m across. This has worked the best for us, and it has the least reflections at any frequency we can reliably test at. I would guess that some form of hard material on top of this type of table would support 200lBs. Michael Sundstrom NOKIA TCC Dallas / EMC ofc: (972) 374-1462 cell: (817) 917-5021 amateur call: KB5UKT -Original Message- From: ext Pommerenke, David [mailto:davi...@ece.umr.edu] Sent: Thursday, November 01, 2001 3:16 PM To: 'POWELL, DOUG'; EMC-PSTC (E-mail) Subject: RE: EMC test table construction plans Doug, For emissions and immunity you should not use any wood in the table. It will significantly (+/-2 dB up to 1 GHz for emissions , more above, +/-10 dB for immunity up to 1 GHz) change the test result. My experience has shown that Styrofoam is basicly the best material. There are a couple of published papers on this issue. As surface material the following worked out fine: - Foamed PVC (rather stiff, low dielectric constant due to the foamed nature), maybe 4 mm thick. - PE sheet, maybe 2 mm thick. David Pommerenke -Original Message- From: POWELL, DOUG [mailto:doug.pow...@aei.com] Sent: Thursday, November 01, 2001 11:38 AM To: EMC-PSTC (E-mail) Subject: EMC test table construction plans Hello all, I plan to construct my own insulated EMC test table for a 5 meter chamber. Seems simple enough to do and I could easily come up with something. I thought I might first ask for input from those of you in the discussion group who have experience or maybe even construction plans. Here are some features I want: 1) I will be testing products that weight up to 200 Lbs (91 kg). 2) I want to minimize metalic fastners. 3) I would like to make it a pivoting table (not motorized). 4) Height is 80 cm. 5) The surface should be replacable if it gets badly worn or scarred. I'm thinking of using hardboard. 6) Suggestions on length width? -doug --- Douglas E. Powell, Compliance Engineer Advanced Energy Industries, Inc. Mail stop: 203024 1626 Sharp Point Drive Ft. Collins, CO 80525 970.407.6410 (phone) 970-407.5410 (fax) mailto:doug.pow...@aei.com --- _ This message, including any attachments, may contain information that is confidential and proprietary information of Advanced Energy Industries, Inc. The dissemination, distribution, use or copying of this message or any of its attachments is strictly prohibited without the express written consent of Advanced Energy Industries, Inc. --- 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server. --- 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy
Re: Safety Critical etc - the future
John Woodgate j...@jmwa.demon.co.uk If you are referring to my post, I plan to report that there is discussion here on the subject, and recount some of the points made. What we need is a very-widely accepted standard definition. Thank you, John. We are here but to serve ... grin - Doug McKean --- 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
RE: EMC test table construction plans
Doug, Wood is ok if you seal it properly to prevent absorbed moisture from causing inconsistancies from one test to the next. Most clear resins do not cause RF problems whereas the metallic pigments in paints often do. If you can, covering the top with laminate (Formica) increases durability and provides a low friction surface. The best design is to make a sturdy table using the following criteria: 4 X 4 or doubled 2 X 4 legs. Top of 2 layers of 3/4 plywood or particle board. Apron to support legs of at least 2 X 4 or 3/4 X 6 cross section. Pivoting top overlay of 3/4 plywood or particle board with a piece of 1 1/2 PVC pipe for a pivot. What you do is either cover the table surfaces (top bottom) with laminate or sand, seal (multiple coats) and sand again plus wax to allow easy rotation. Drill matching holes through the center of the 3/4 overlay and the tabletop for the stub (4 long or so) of pipe. glue the pipe flush with the top of the overlay (it will protrude from the bottom). You just drop the overlay with pipe onto/into the tabletop with hole. During testing the table is rotated (1/4 turn) manually between tests. If you doubt that laminate can provide a low friction bearing, try this test - turn one table upside down on top of an identical table, rotate the top table, and then try rotating the table with a coworker standing on it. If you find too much friction apply some automotive paste wax. Scott Lacey -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of POWELL, DOUG Sent: Thursday, November 01, 2001 12:38 PM To: EMC-PSTC (E-mail) Subject: EMC test table construction plans Hello all, I plan to construct my own insulated EMC test table for a 5 meter chamber. Seems simple enough to do and I could easily come up with something. I thought I might first ask for input from those of you in the discussion group who have experience or maybe even construction plans. Here are some features I want: 1) I will be testing products that weight up to 200 Lbs (91 kg). 2) I want to minimize metalic fastners. 3) I would like to make it a pivoting table (not motorized). 4) Height is 80 cm. 5) The surface should be replacable if it gets badly worn or scarred. I'm thinking of using hardboard. 6) Suggestions on length width? -doug --- Douglas E. Powell, Compliance Engineer Advanced Energy Industries, Inc. Mail stop: 203024 1626 Sharp Point Drive Ft. Collins, CO 80525 970.407.6410 (phone) 970-407.5410 (fax) mailto:doug.pow...@aei.com --- _ This message, including any attachments, may contain information that is confidential and proprietary information of Advanced Energy Industries, Inc. The dissemination, distribution, use or copying of this message or any of its attachments is strictly prohibited without the express written consent of Advanced Energy Industries, Inc. --- 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server. --- 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
