Re: [PSES] Adding more than one EUT

Sat, 18 Feb 2023 16:18:28 -0800 

I'm being a bit flippant, but;
- If I was in my 3rd-party test house role, it stops when the customer says stop. - If I am the steward of my company's product, it stops when my "engineering judgement" says we've "done our best to find the worst". šŸ˜ 

Assuming, of course, that it's a DoC product for the US and EU.

Brent

On 2/18/2023 3:51 PM, Dan Roman wrote:



Back in a previous life when I worked on PCIe, VME, etc. boards that 
plugged into a chassis, we would frequently start adding cards until 
we saw no increase in emissions to satisfy compliance if a customer 
used multiples of our boards, which was often the case.Ā  These were 
components however and to me it seems a bit murkier if an end product 
that could function standalone is used with others, especially if each 
has its own power cord.



Even in my case with the PC cards, we didnā€™t test multiples of every 
combination of boards we sold, it would be impossible to do.Ā  Does the 
manufacturer of an LED light bulb need to test just one bulb or do 
they need to find the fixture that holds the most lightbulbs and test 
in that?Ā  I donā€™t think so much in the same way that a server 
manufacturer tests one server and doesnā€™t need to find the customer 
that puts the most servers in a rack or a computer room and test that 
number of servers.Ā  Perhaps if they are selling a rack of servers that 
uses a common power cord?


Where does it stop?

Dan

*From:*John Mcbain [mailto:johnmcb...@ieee.org]
*Sent:* Saturday, February 18, 2023 2:20 PM
*To:* EMC-PSTC@LISTSERV.IEEE.ORG
*Subject:* Re: [PSES] Adding more than one EUT

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.Ā  What 
exactly is the product being sold?Ā  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 changesĀ are being made to the product" 
(wrong!) why bother telling the compliance engineer?Ā  Been there!



Best regards,

John McBain


On Sat, Feb 18, 2023 at 7:37 AM Brent DeWitt <bdew...@ix.netcom.com> 
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:

        Iā€™m finding this an extremely interesting discussion. I donā€™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.Ā  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 <johnmcb...@ieee.org
        <http://johnmcb...@ieee.org>>
        *Reply-To: *John Mcbain <johnmcb...@ieee.org
        <http://johnmcb...@ieee.org>>
        *Date: *Fri, 17 Feb 2023 14:22:44 -0800
        *To: *<EMC-PSTC@LISTSERV.IEEE.ORG
        <http://EMC-PSTC@LISTSERV.IEEE.ORG>>
        *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 IFadding 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.Ā  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.Ā  ;-)

        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 aĀ  product sold as a complete all-included
        system.

        Best regards,
        John McBain


        On Fri, Feb 17, 2023 at 1:59 PM James Pawson (U3C)
        <ja...@unit3compliance.co.uk
        <http://ja...@unit3compliance.co.uk>> 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,



            Iā€™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, Iā€™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
            thatā€™s how the system is likely to be used also..



            Is there a legal requirement or precedent on how this
            should be tested as Iā€™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 <emc-p...@ieee.org
            <http://emc-p...@ieee.org>>



            All emc-pstc postings are archived and searchable on the
            web at:

            http://www.ieee-pses.org/emc-pstc.html
            <http://www.ieee-pses.org/emc-pstc.html>



            Website: http://www.ieee-pses.org/ <http://www.ieee-pses.org/>

            Instructions: http://www.ieee-pses.org/list.html
            <http://www.ieee-pses.org/list.html>(including how to
            unsubscribe)

            List rules: http://www.ieee-pses.org/listrules.html
            <http://www.ieee-pses.org/listrules.html>



            For help, send mail to the list administrators:

            Mike Cantwell <mcantw...@ieee.org <http://mcantw...@ieee.org>>



            For policy questions, send mail to:

            Jim Bacher: Ā <j.bac...@ieee.org <http://j.bac...@ieee.org>>

            David Heald: <dhe...@gmail.com <http://dhe...@gmail.com>>

            _________________________________________________

            To unsubscribe from the EMC-PSTC list, click the following
            link:
            https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1
            <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 &LT;emc-p...@ieee.org&GT
            <http://emc-p...@ieee.org&GT>;

            All emc-pstc postings are archived and searchable on the
            web at: http://www.ieee-pses.org/emc-pstc.html
            <http://www.ieee-pses.org/emc-pstc.html>

            Website: http://www.ieee-pses.org/ <http://www.ieee-pses.org/>
            Instructions: http://www.ieee-pses.org/list.html
            <http://www.ieee-pses.org/list.html>(including how to
            unsubscribe) <http://www.ieee-pses.org/list.html
            <http://www.ieee-pses.org/list.html>>
            List rules: http://www.ieee-pses.org/listrules.html
            <http://www.ieee-pses.org/listrules.html>

            For help, send mail to the list administrators:
            Mike Cantwell &LT;mcantw...@ieee.org&GT
            <http://mcantw...@ieee.org&GT>;

            For policy questions, send mail to:
            Jim Bacher Ā &LT;j.bac...@ieee.org&GT
            <http://j.bac...@ieee.org&GT>;
            David Heald &LT;dhe...@gmail.com&GT
            <http://dhe...@gmail.com&GT>;

            
------------------------------------------------------------------------


            Ā To unsubscribe from the EMC-PSTC list, click the
            following link:
            https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1
            <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 <emc-p...@ieee.org
        <http://emc-p...@ieee.org>>

        All emc-pstc postings are archived and searchable on the web
        at: http://www.ieee-pses.org/emc-pstc.html
        <http://www.ieee-pses.org/emc-pstc.html>

        Website: http://www.ieee-pses.org/ <http://www.ieee-pses.org/>
        Instructions: http://www.ieee-pses.org/list.html
        <http://www.ieee-pses.org/list.html>(including how to
        unsubscribe) <http://www.ieee-pses.org/list.html
        <http://www.ieee-pses.org/list.html>>
        List rules: http://www.ieee-pses.org/listrules.html
        <http://www.ieee-pses.org/listrules.html>

        For help, send mail to the list administrators:
        Mike Cantwell <mcantw...@ieee.org <http://mcantw...@ieee.org>>

        For policy questions, send mail to:
        Jim Bacher Ā <j.bac...@ieee.org <http://j.bac...@ieee.org>>
        David Heald <dhe...@gmail.com <http://dhe...@gmail.com>>

        ------------------------------------------------------------------------


        Ā To unsubscribe from the EMC-PSTC list, click the following
        link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1
        <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 <emc-p...@ieee.org>

        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 <mcantw...@ieee.org>

        For policy questions, send mail to:
        Jim Bacher <j.bac...@ieee.org>
        David Heald <dhe...@gmail.com>

        ------------------------------------------------------------------------

        To unsubscribe from the EMC-PSTC list, click the following
        link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1
        <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 &LT;emc-p...@ieee.org&GT;

    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 &LT;mcantw...@ieee.org&GT;

    For policy questions, send mail to:
    Jim Bacher &LT;j.bac...@ieee.org&GT;
    David Heald &LT;dhe...@gmail.com&GT;

    ------------------------------------------------------------------------

    To unsubscribe from the EMC-PSTC list, click the following link:
    https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1
    <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 <emc-p...@ieee.org>



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 <mcantw...@ieee.org>

For policy questions, send mail to:
Jim Bacher <j.bac...@ieee.org>
David Heald <dhe...@gmail.com>

------------------------------------------------------------------------


To unsubscribe from the EMC-PSTC list, click the following link: 
https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1 
<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 <emc-p...@ieee.org>



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 <mcantw...@ieee.org>

For policy questions, send mail to:
Jim Bacher <j.bac...@ieee.org>
David Heald <dhe...@gmail.com>

------------------------------------------------------------------------


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 <emc-p...@ieee.org>

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 <mcantw...@ieee.org>

For policy questions, send mail to:
Jim Bacher:  <j.bac...@ieee.org>
David Heald: <dhe...@gmail.com>
_________________________________________________
To unsubscribe from the EMC-PSTC list, click the following link: 
https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1























					Reply via email to