Hi Brent - Yes, different testing certainly would be appropriate for different power distribution and connection methods, so knowing ALL the details is very important to decide how to test.
However, one *essential* piece of knowledge may be overlooked. What exactly is the product being sold? Marketing plays a *huge* role in knowing what to test, and decisions made by Marketing AFTER the product is released can create non-compliant products without a single physical change being made. Common case - let's sell this new combination of equipment as a single product. And of course, since "no changes are being made to the product" (wrong!) why bother telling the compliance engineer? Been there! Best regards, John McBain On Sat, Feb 18, 2023 at 7:37 AM Brent DeWitt <[email protected]> wrote: > An unanswered, and critical, question is: > Do the "daisy-chained" devices draw power produced by the initial item, or > do they all have independent power supplies? > > - First case: Initial unit produces DC/AC for the additional units. > - Second case: the initial unit is a simple, passive "power strip" for the > additional units. > > In the first case, I would expect testing as a system, with all units > attached > In the second case, I would test a single unit. > > Another implication is for radiated emissions. What is the expected > spacing between units in the typical users. > > with respect, > > Brent DeWitt > Milford, MA > > On 2/17/2023 9:56 PM, Ken Javor wrote: > > I’m finding this an extremely interesting discussion. I don’t have > anything definitive to offer, but I do have a question to help stir the pot. > > If the possibility that multiple items might be used together and that > emissions will be additive in some fashion is a justification for testing > multiple units at a time, what about ... light bulbs? > > Meaning CFLs or LEDs. > > My house is full of them. It is reasonable to assume that most > homes/businesses are. Perhaps the emissions limits for these were based on > this reasonably foreseeable outcome? > > Ken Javor > Phone: (256) 650-5261 > > > ------------------------------ > *From: *John Mcbain <[email protected]> > *Reply-To: *John Mcbain <[email protected]> > *Date: *Fri, 17 Feb 2023 14:22:44 -0800 > *To: *<[email protected]> > *Subject: *Re: [PSES] Adding more than one EUT > > Hi Derek - > > Typical requirement for a unit that may be sold and used in multiples > (that is, all the units can be sold together as one product) is you can > test just one IF adding the other units does not increase the emissions. > > Of course the most practical way to determine that is to assemble the > multiple units to see what happens. If the test result for testing max. > connected units compared to testing only one unit shows no significant > difference, then you're good - but definitely archive those test results! > > If you can't pass the test with all units connected, then whatever you do, > don't let Marketing create a multiple-unit product to sell. ;-) > > Similarly, the desktop PC system that James mentioned would have all power > cords separately tested for conducted emissions as a fully connected system > (monitor, printer, scanner, etc. attached) if it is a product sold as a > complete all-included system. > > Best regards, > John McBain > > > On Fri, Feb 17, 2023 at 1:59 PM James Pawson (U3C) < > [email protected]> wrote: > > > Hi Derek, > > > Is the daisy chain connection the AC supply or some other power bus? > > > How is 8 units daisy chained any different to 8 separate units all on the > same power bus? We are looking for individual emission contributions from > each connected unit. > > > If measuring conducted emissions on a desktop pc (y'know, the big ones we > had before everyone had laptops to work from home...) the you would just > measure the PC, not the monitor and printer and scanner and modem and and > and... > > > Just thinking aloud > > All the best > > James > > > ---- Lfresearch wrote ---- > > Hi folks, > > > > I’ve been asked to test a light fixture that has the ability to be daisy > chained up to 8 units. > > > > When I run conducted emissions, I’m wondering if I need to insist on > having 8 units plugged in at once i.e. fully populated, OR, can I just test > one fixture at a time since that’s how the system is likely to be used > also.. > > > > Is there a legal requirement or precedent on how this should be tested as > I’m going round in circles arguing with myself here. > > > > Thanks, > > > > Derek. > > > > SSCLabs, > > Reno, NV. > > - > > ---------------------------------------------------------------- > > 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 > > > > 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: > > Mike Cantwell <[email protected]> > > > > For policy questions, send mail to: > > Jim Bacher: <[email protected]> > > David Heald: <[email protected]> > > _________________________________________________ > > To unsubscribe from the EMC-PSTC list, click the following link: > https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1 > > - > ---------------------------------------------------------------- > > 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 > > 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: > Mike Cantwell <[email protected]> > > For policy questions, send mail to: > Jim Bacher <[email protected]> > David Heald <[email protected]> > ------------------------------ > > To unsubscribe from the EMC-PSTC list, click the following link: > https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1 > > - > ---------------------------------------------------------------- > > 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 > > 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: > Mike Cantwell <[email protected]> > > For policy questions, send mail to: > Jim Bacher <[email protected]> > David Heald <[email protected]> > ------------------------------ > > To unsubscribe from the EMC-PSTC list, click the following link: > https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1 > > - > ---------------------------------------------------------------- > > 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 > > 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: > Mike Cantwell <[email protected]> > > For policy questions, send mail to: > Jim Bacher <[email protected]> > David Heald <[email protected]> > ------------------------------ > > To unsubscribe from the EMC-PSTC list, click the following link: > https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1 > > > - > ---------------------------------------------------------------- > > 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 > > 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: > Mike Cantwell <[email protected]> > > For policy questions, send mail to: > Jim Bacher <[email protected]> > David Heald <[email protected]> > ------------------------------ > > To unsubscribe from the EMC-PSTC list, click the following link: > https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1 > - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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