RE: About Radiated Measurements
Muriel, What is the size of the equipment the power supplies will fit into? Can this be tested within you GTEM cell? I would prefer to put cables and load into the GTEM cell. I am using a GTEM cell for quite a while for pre-compliance testing and made good experiences. There are - as already pointed out - some things to take care of: - Cables connected to the EUT exiting the GTEM cell and other cables with in the cell have a great influence on the result from their positioning within the GTEM cell and their filtering when going outside. - To get an impression of the relevance of your testing choose an EUT that fits completely in your GTEM cell and conduct a comparative measurement on an OATS. - If you are doubting a result repaeat the test - I do not know what parameters you are using for a prescan - there are peaks which might occur due to a single event when you do a peak measurement and others might not be there. The measurement time has a great influence on the recording of short time events (yawn, I know, but I stress this point as I forget it often myself :-| ) But - before you put it in - what is the maximum thermal load for an EUT within your GTEM cell? Please excuse if I touched points that you already considered. For a better testing repeatability of EUTs with many cables within GTEM cells there are manipulator arms with cable guides. Schaffner is one of the manufacturers of such things. Best regards, Michael Nagel -Original Message- From: Muriel Bittencourt de Liz [mailto:mur...@eel.ufsc.br] Sent: Donnerstag, 20. Februar 2003 19:52 To: EMC-PSTC List Subject: About Radiated Measurements Group, I have a doubt concerning radiated emissions measurement: - For radiated emissions measurement of switched mode power supplies using a TEM cell, should I leave the loads of the supply inside or outside the cell?? My TEM cell have filtered connections for DC loads. Thanks in advance for your help. Best Regards, Muriel --- 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: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org 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
Re: About Radiated Measurements
My opinion. The frequencies radiated by the output leads of an SMPS are such that the wires are the only significant radiator, not the loads. So it would not matter if the loads were within the cell, or without. But it is easier to put them within the cell and not worry about filtering the leads, unless heat build-up is an issue. If this is an SMPS for a PC or a similar application with very short output leads then I see no problems, but if it were a stand-alone power supply that drives long leads, then the radiation efficiency of wires within a typical TEM cell will not represent the real world and it would be better to monitor current on the wires and predict the radiated fields from real world-length wires with the measured current. Ditto for the input power leads, except here it is a given the leads are long. Ken Javor on 2/20/03 1:51 PM, Muriel Bittencourt de Liz at mur...@eel.ufsc.br wrote: Group, I have a doubt concerning radiated emissions measurement: - For radiated emissions measurement of switched mode power supplies using a TEM cell, should I leave the loads of the supply inside or outside the cell?? My TEM cell have filtered connections for DC loads. Thanks in advance for your help. Best Regards, Muriel --- 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: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org 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
RE: About Radiated Measurements
Muriel, interesting question. Considering common mode noise on the load wires: With the load at the end of the wires, but not grounded, you have a monopole antenna. With the load wires terminated into a filter (I'm assuming low-Z to GND) you have a loop antenna. I ran a quick simulation using NEC-2 at 100 MHz using a wire length of 13 cm for an inverted-L configuration (3 cm vertically and 10 cm horizontally). The loop has dimensions are; 3 cm vertically, 10 cm horizontal, and 3 cm back to GND. Given 1 mV and a 10 ohm source impedance the loop radiates 19 pW. Given the 1 mV source the monopole radiates 47 fW. A 26 dB difference given these parameters. Placing the power supply outside through filters is the winner for the most radiation, given these randomly selected parameters. Are you orienting the power supply on each of the three axis? And rotating it at each? This is what I have found inconvenient about TEM cells. Dave Cuthbert Micron Technology From: Muriel Bittencourt de Liz [mailto:mur...@eel.ufsc.br] Sent: Thursday, February 20, 2003 11:52 AM To: EMC-PSTC List Subject: About Radiated Measurements Group, I have a doubt concerning radiated emissions measurement: - For radiated emissions measurement of switched mode power supplies using a TEM cell, should I leave the loads of the supply inside or outside the cell?? My TEM cell have filtered connections for DC loads. Thanks in advance for your help. Best Regards, Muriel 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: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org 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
RE: About Radiated Measurements
I would have to concur. My experience with GTEMs, is that cables exiting the cell create measurement errors. Mat Aschenberg From: brent.dew...@us.datex-ohmeda.com [mailto:brent.dew...@us.datex-ohmeda.com] Sent: Thursday, February 20, 2003 1:14 PM To: Muriel Bittencourt de Liz Cc: EMC-PSTC List Subject: Re: About Radiated Measurements Muriel, I would suggest leaving them inside connected by a length of wire that is somewhat representative of the size of the final application. Best yet, do it both ways and see if it makes a diference. Regards, Brent DeWitt Muriel Bittencourt de Liz mur...@eel.ufsc.br@majordomo.ieee.org on 20-02-2003 12:21:38 PM Please respond to Muriel Bittencourt de Liz mur...@eel.ufsc.br Sent by: owner-emc-p...@majordomo.ieee.org To: EMC-PSTC List emc-p...@ieee.org cc: Subject: About Radiated Measurements Group, I have a doubt concerning radiated emissions measurement: - For radiated emissions measurement of switched mode power supplies using a TEM cell, should I leave the loads of the supply inside or outside the cell?? My TEM cell have filtered connections for DC loads. Thanks in advance for your help. Best Regards, Muriel 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: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org 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
Re: About Radiated Measurements
Muriel, I would suggest leaving them inside connected by a length of wire that is somewhat representative of the size of the final application. Best yet, do it both ways and see if it makes a diference. Regards, Brent DeWitt Muriel Bittencourt de Liz mur...@eel.ufsc.br@majordomo.ieee.org on 20-02-2003 12:21:38 PM Please respond to Muriel Bittencourt de Liz mur...@eel.ufsc.br Sent by: owner-emc-p...@majordomo.ieee.org To: EMC-PSTC List emc-p...@ieee.org cc: Subject: About Radiated Measurements Group, I have a doubt concerning radiated emissions measurement: - For radiated emissions measurement of switched mode power supplies using a TEM cell, should I leave the loads of the supply inside or outside the cell?? My TEM cell have filtered connections for DC loads. Thanks in advance for your help. Best Regards, Muriel 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: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org 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
