I have to admit I don¹t fully understand the mathematical argument, so I¹ll leave that be, but the practical objections from Mr. Marshall and the mode conversion argument from Mr. Gremmen don¹t ring true to me as concerns about dm to cm conversion.
I know that European mains distribution is different and higher impedance than American due to more loads running off the same pole transformer, and that therefore there can be more interaction farther away, but by the same token, the limit I was looking at relaxing was the old FCC class B 48 dBuV one, so the suggested relaxation was to 68 dBuV dm from 450 kHz to 30 MHz (and checked to be valid all the way down to 150 kHz on a few European model radios I obtained that had that lower LW band from 150 300 kHz). The CISPR limit at 150 kHz is somewhere around 68 dBuV anyway, and the limit flattens out at 60 dBuV (if memory serves) at higher frequencies, so the European limit was already relaxed cm and dm, relative to the limit I was investigating. According to these two posts from Mssrs. Gremmen and Marshall, the present CISPR limit (to which I believe the USA has also harmonized since that time) shouldn't be working at all, at least by my understanding of my work and what they are saying. Ken Javor Ken Javor Phone: (256) 650-5261 > From: "ce-test, qualified testing bv - Gert Gremmen" <[email protected]> > Reply-To: "ce-test, qualified testing bv - Gert Gremmen" <[email protected]> > Date: Fri, 1 Apr 2016 12:15:24 +0200 > To: <[email protected]> > Conversation: [PSES] Commom mode current vs. differential mode current and > LISN > Subject: Re: [PSES] Commom mode current vs. differential mode current and LISN > > I needed to add to my previous contribution to that the parameter that > controls this is called TCL value. > (John et all: = Transferse Conversion Loss ;<)) . The EMC world has been using > LISNS > for decades now that simulate a LCL (Longitudinal Conversion Loss) value of > the connected mains cable of -6 dB. > (for a cable LCL and TCL are normally the same) > Something to think about... > > Regards, > > Ing. Gert Gremmen > Approvals manager > ------------------------------------------------------------------------------ > ------ > > > + ce marking of electrical/electronic equipment > + Independent Consultancy Services > + Compliance Testing and Design for CE marking > according to EC-directives: > - Electro Magnetic Compatibility 2004/108/EC > - Electrical Safety 2006/95/EC > - Medical Devices 93/42/EC > - Radio & Telecommunication Terminal Equipment 99/5/EC > + Improvement of Product Quality and Reliability testing > + Education > > Web: www.cetest.nl (English) > Phone : +31 10 415 24 26 > ------------------------------------------------------------------- > This e-mail and any attachments thereto may contain information > that is confidential and/or protected by intellectual property rights > and are intended for the sole use of the recipient(s) named above. > Any use of the information contained herein (including, but not > limited to, total or partial reproduction, communication or > distribution in any form) by persons other than the designated > recipient(s) is prohibited. If you have received this e-mail in error, > please notify the sender either by telephone or by e-mail and > delete the material from any computer. > Thank you for your co-operation. > > From: Richard Marshall [mailto:[email protected]] > Sent: Friday 1 April 2016 11:48 > To: [email protected] > Subject: Re: [PSES] Commom mode current vs. differential mode current and LISN > > Ken says > "I seem to recall Michel Mardiguian writing that the relaxed dm could > transform into cm causing big problems. That seems counter-intuitive at > best." > > > Think about it this way. DM is being transmitted along a wire PAIR > that we must view as an rf transmission line, which is balanced UNTIL it meets > some discontinuity. > > ( What discontinuity? > - A branch cable with a single-pole switch that is open, leaving a branch wire > hanging on the other pole. > - A device with a single class X capacitor from neutral to ground. > - A solid ground connection to the neutral wire. > - A wide separation between Line and Neutral conductor (Think 2-way light > switching) > - - etc ) > > At a discontinuity that is unbalanced relative to ground (as all the above > are), there is conversion of DM power into CM because unequal amounts of the > balanced power in each wire are diverted to ground. > The maths. are complicated because of the various and different values of > Characteristic impedance Zo between wires and from each wire to ground, but > the mechanism for power transfer is clear. > > There have been studies of this in the last 10/15 years suggesting that > typical power transfer coupling from DM to CM in a real mains power network at > 230 volts ( I do not know of any at 115 volts, perhaps others do...) involves > only about 10dB power loss at some frequencies where the wiring is resonant. > > So whilst there may be a case for allowing a bit more DM than CM, there can be > no technical case for allowing 20dB or more of excess DM. Not on ordinary > power distribution circuits. > > > Richard > > Richard Marshall Laboratories, > 30 Ox Lane, Harpenden, Herts., AL5 4HE, UK > +44 (0)1582 460815 www.design-emc.co.uk > Member of the EMC Industry Association > > From: Ken Javor [mailto:[email protected]] > Sent: 30 March 2016 21:59 > To: [email protected] > Subject: Re: [PSES] Commom mode current vs. differential mode current and LISN > > With the dm limit 20 dB relaxed, the dm filter design would be simplified. As > I said, an industry study said it would save $35 million a year for the power > supply industry. I'm not sure if it was Art Wall as much as the old guard who > were involved in the original work not liking a fresh look at it. > > I seem to recall Michel Mardiguian writing that the relaxed dm could transform > into cm causing big problems. That seems counter-intuitive at best. The > opposite is way more likely. So my takeaway was that they didn't want to > consider a change to how they had set thing up. > > Ken Javor > Ph. (256) 650-5261 > > ________________________________________ > From: "Grasso, Charles" <[email protected]> > Date: Wed, 30 Mar 2016 19:01:00 +0000 > To: Ken Javor <[email protected]>, "[email protected]" > <[email protected]> > Conversation: [PSES] Commom mode current vs. differential mode current and > LISN > Subject: RE: [PSES] Commom mode current vs. differential mode current and LISN > > Hello Ken - I remember the setup and demo to Art Wall of the FCC during the > 1999 EMC Symposium here in Denver. > In spite of your best efforts it was clear that Art was not "persuaded" !! > > The impact on the industry (as I recall) would be much cheaper filters...(if > any). > > > > Best Regards > Charles Grasso > Compliance Engineer > Echostar Communications > (w) 303-706-5467 > (c) 303-204-2974 > (t) [email protected] > (e) [email protected] > (e2) [email protected] > > > From: Ken Javor [mailto:[email protected]] > Sent: Tuesday, March 29, 2016 3:48 PM > To: [email protected] > Subject: Re: [PSES] Commom mode current vs. differential mode current and LISN > > The report on which the old 48 dBuV class B CE limit was based did develop > that based on the conducted susceptibility of AM and shortwave radios, but it > also noted that limit functioned as an adequate control for common mode noise > that would radiate as per Doug's observation. Back in the late '90s I > presented a detailed test report to TC77 showing that if instead of > controlling conducted emissions at each LISN port, they instead controlled by > modes, that dm could be relaxed 20 dB to 68 dBuV and the committee took an > action item and back then said if that were implemented, it would save the > power supply industry $35 million a year. The work I did was based on using > the LISNMATE / LISNMARK technology as injection tools injecting pure cm and dm > and showing that the susceptibility to dm was 20 dB less, because of bulk > filter caps on the secondary of power supplies, whereas there were no Y-caps > and no cm filtering. The reason this was missed back in 1977/78 when the > report was w! > ritten was they used a single LISN with neutral through the case. CM and DM > flowed in the same path. > > Ken Javor > Ph. (256) 650-5261 > ________________________________________ > From: Doug Smith <[email protected]> > Reply-To: <[email protected]> > Date: Tue, 29 Mar 2016 14:31:20 -0700 > To: <[email protected]>, Ken Javor <[email protected]> > Subject: Re: [PSES] Commom mode current vs. differential mode current and LISN > > Hi Ken and the group, > > > > I always thought that the FCC measures the wrong quantity for conducted > emmissions. What shoud be measured is all conductors (two or three including > phase/neutral/protective earth) together as common mode current as that is > what radiates from the long power lines causing problems for shortwave > receivers and Amateur Radio Operators. The old demonstration of conducted EMI > into AM radios is not so useful, especially today. > > > > Below 30 MHz, most devices are not large enough to radiate efficiently, but > the power wiring is long enough to radiate. I have a case of EMI in my house > from two Feit Electric LED floodlights that meet conducted emissions, but I > can't use a hand held, battery powered, shortwave receiver when the two are on > except to walk quite a distance from that part of the house. The FCC test may > catch this case, but apparently not for me, as there are only two wires but > that is not the case for other devices. > > > > So phase+neutral could be noisy with respect to protective earth but as long > as it is balanced by an opposite current on protective earth, radiation should > be low. > > > > Any other Amateur Radio operators want to weigh in on this? > > > > Doug (K4OAP, since 1959) > > > > > > > > > On Tue, 29 Mar 2016 16:13:58 -0500, Ken Javor <[email protected]> > wrote: > > Re: [PSES] Commom mode current vs. differential mode current and LISN > Disagree. Westin had it right. A current probe can be used to isolate either > cm or dm current. If at any frequency the signal amplitude on individual line > and neutral conductors are very close, then all you can say is that at that > frequency either cm or dm predominates, but you can't say which. With a LISN, > a separate device must be used. Mark Nave of EMC Services designed a three > port device (connects to each LISN port and to the EMI receiver) trademarked > LISNMATE in the 1980s to isolate common mode, and sometime later he produced > LISNMARK, which isolated DM. Within the past decade, Ray Adams while at > Fischer Custom Communications packed both functions in one piece of equipment, > which if memory serves was named LISNUP. > > EMC Services, Mark Nave's company, is no longer producing his products, but I > believe the FCC product is still available. > > Ken Javor > Ph. (256) 650-5261 > ________________________________________ > From: Elliott Martinson <[email protected]> > Reply-To: Elliott Martinson <[email protected]> > Date: Tue, 29 Mar 2016 20:36:18 +0000 > To: <[email protected]> > Conversation: [PSES] Commom mode current vs. differential mode current and > LISN > Subject: Re: [PSES] Commom mode current vs. differential mode current and LISN > > http://www.hottconsultants.com/techtips/CM_vs_DM%20Conducted_Emission.html > This is a great resource for your question. > > Your second point kind of contradicts your first, if it's trying to say what > I think it is. DM and CM each show up on L, but the same is true for N. It's a > linear combination of both, so even if L and N are almost equal, you can't say > anything about the proportion of DM to CM currents. > > If they are not equal, then this implies current is travelling back via the > ground conductor and/or energy's being lost to radiated emissions. > > What you need is a physical circuit to do the adding/subtracting of the LISN > outputs. (otherwise your 3rd bullet point is correct) > > Your 4th bullet, well I refer you to the link above. > > > Elliott Martinson > Product Assurance Specialist I > Electronic Theatre Controls > 3031 N PLEASANT VIEW RD > MIDDLETON WI 53562-4809 > Work: 608.824.5696 / Cell: 608.209.9897 > [email protected] <[email protected]> > > > From: Amund Westin [mailto:[email protected]] > <mailto:[email protected]%5D> > Sent: Tuesday, March 29, 2016 1:23 PM > To: [email protected] > Subject: [PSES] Commom mode current vs. differential mode current and LISN > > Please correct me, if I am wrong (that happens quite often ...): > > · Let one wire (L) pass through a current clamp, and you measure the > combination of current mode and differential mode currents > > · Do the same with wire N. If L and N are (almost) equal, you either > have major part of DM currents or major part of CM current > > · Let both wire (L and N) pass through a current clamp, and you measure > the only CM current (DM is canceled) > > · When doing conducted emission test by LISN, you actually get what > you get. LISN do not see the difference between CM or DM. From LISN > measurements, you can't say if noise is CM or DM. > > B.regards > > Amund > > > > > > > > > > > > > > - > ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society emc-pstc > discussion list. To post a message to the list, send your e-mail to > <[email protected]> > > All emc-pstc postings are archived and searchable on the web at: > http://www.ieee-pses.org/emc-pstc.html > > Attachments are not permitted but the IEEE PSES Online Communities site at > http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used > formats), large files, etc. > > Website: http://www.ieee-pses.org/ > Instructions: http://www.ieee-pses.org/list.html (including how to > unsubscribe) <http://www.ieee-pses.org/list.html> > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > Scott Douglas <[email protected]> > Mike Cantwell <[email protected]> > > For policy questions, send mail to: > Jim Bacher <[email protected]> > David Heald <[email protected]> > - > ---------------------------------------------------------------- > > This message is from the IEEE Product Safety Engineering Society emc-pstc > discussion list. To post a message to the list, send your e-mail to > <[email protected]> > > All emc-pstc postings are archived and searchable on the web at: > http://www.ieee-pses.org/emc-pstc.html > > Attachments are not permitted but the IEEE PSES Online Communities site at > http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used > formats), large files, etc. > > Website: http://www.ieee-pses.org/ > Instructions: http://www.ieee-pses.org/list.html (including how to > unsubscribe) <http://www.ieee-pses.org/list.html> > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > Scott Douglas <[email protected]> > Mike Cantwell <[email protected]> > > For policy questions, send mail to: > Jim Bacher <[email protected]> > David Heald <[email protected]> > > - > ---------------------------------------------------------------- > > This message is from the IEEE Product Safety Engineering Society emc-pstc > discussion list. 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To post a message to the list, send your e-mail to > <[email protected]> > > All emc-pstc postings are archived and searchable on the web at: > http://www.ieee-pses.org/emc-pstc.html > > Attachments are not permitted but the IEEE PSES Online Communities site at > http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used > formats), large files, etc. > > Website: http://www.ieee-pses.org/ > Instructions: http://www.ieee-pses.org/list.html (including how to > unsubscribe) <http://www.ieee-pses.org/list.html> > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > Scott Douglas <[email protected]> > Mike Cantwell <[email protected]> > > For policy questions, send mail to: > Jim Bacher <[email protected]> > David Heald <[email protected]> > - > ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society emc-pstc > discussion list. To post a message to the list, send your e-mail to > <[email protected]> > All emc-pstc postings are archived and searchable on the web at: > http://www.ieee-pses.org/emc-pstc.html > Attachments are not permitted but the IEEE PSES Online Communities site at > http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used > formats), large files, etc. > Website: http://www.ieee-pses.org/ > Instructions: http://www.ieee-pses.org/list.html (including how to > unsubscribe) > List rules: http://www.ieee-pses.org/listrules.html > For help, send mail to the list administrators: > Scott Douglas <[email protected]> > Mike Cantwell <[email protected]> > For policy questions, send mail to: > Jim Bacher <[email protected]> > David Heald <[email protected]> > - > ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society emc-pstc > discussion list. To post a message to the list, send your e-mail to > <[email protected]> > All emc-pstc postings are archived and searchable on the web at: > http://www.ieee-pses.org/emc-pstc.html > Attachments are not permitted but the IEEE PSES Online Communities site at > http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used > formats), large files, etc. > Website: http://www.ieee-pses.org/ > Instructions: http://www.ieee-pses.org/list.html (including how to > unsubscribe) > List rules: http://www.ieee-pses.org/listrules.html > For help, send mail to the list administrators: > Scott Douglas <[email protected]> > Mike Cantwell <[email protected]> > For policy questions, send mail to: > Jim Bacher <[email protected]> > David Heald <[email protected]> > > - > ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society emc-pstc > discussion list. To post a message to the list, send your e-mail to > <[email protected]> > > All emc-pstc postings are archived and searchable on the web at: > http://www.ieee-pses.org/emc-pstc.html > > Attachments are not permitted but the IEEE PSES Online Communities site at > http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used > formats), large files, etc. > > Website: http://www.ieee-pses.org/ > Instructions: http://www.ieee-pses.org/list.html (including how to > unsubscribe) > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > Scott Douglas <[email protected]> > Mike Cantwell <[email protected]> > > For policy questions, send mail to: > Jim Bacher: <[email protected]> > David Heald: <[email protected]> - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
