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UL Compliance

Discussion in 'Electronic Design' started by [email protected], Jul 5, 2013.

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  1. Guest

    Hi ,

    I need some advise regarding compliance testing done by UL. We are intending to design a biomedical device ( an EKG machine) . And we want UL to do compliance testing aganist the following standards

    1. UL 60601-1 (2006)
    2. IEC / EN 60601-1 (1998+A1+A2)
    3. ANSI / AAMI ES60601-1 ( 2005+C1+A2)
    4. IEC EN 60601-1 (2005/2006 + C1+ C2) ( Europe, CE)
    5. 60601-2-26(2002)

    I have no information about the testing methods or what kind of test UL will perform on this device. I do not know about reasons that they can use to reject the device.

    EKG machine:
    1. Operated by UL approved 3.7V, 1A, LiIon battery. Battery can be charged by a UL approved charger. But when the battery is charging, EKG machine will be completely shut down by software. I am using the following "power connector"

    Is this connector a good choice?

    2. I am using the following box

    I do not know what should be the ingress ratings of the box and flammability ratings. Any advise!


    I have gathered following knowledge so far about the tests

    1. Single Fault Condition : I am not able to find any clear answer for that. Can anyone give a simple to undertsaned explanation?
    2. Ingress rating test: do not know how will they test
    3. EMC test
    4. Enclosuer mechanical robustness test.

    What other tests should I keep in mind before we start designing this machine.

  2. Joerg

    Joerg Guest

    Best is to tell them into which market you want to go and they'll test
    to the right standards. My advice would be to also get a quote from a
    TUEV outlet in your area.

    L'il red flag goes up: It is almost inevitable that at some point users
    will try to use the unit with the charger plugged in. You can (and
    should) prevent that via software but someone could still make the
    connection and try. Then the power source must also be 60601 and
    patient-contact rated, single-fault-proof, and so on. IME simple wall
    warts never are.

    If you meant limited to 1A charge current it could work. I would never
    send the "rated" 5A over it.

    Mine we always sealed. Watch that battery compartment. Hard to see but
    if it doesn't have a rubber ring seal chances are thatan incredible
    amount of crud accumulates inside over time.

    It means that if any kind of fault occurs the unit must still fulfill
    60601. Often at a relaxed spec, for example for leakage current.

    Mind EMC, always a concern with plastic enclosures. Have an expert look
    over the design before committing because you have to go through EMC
    testing. Also, cleaning should be looked at. What if a user dunks it
    into water? No matter what the manual says, someone will do that. Also,
    check out G-ratings, for example if it falls onto a tile floor.
  3. Guest

  4. Guest

    I meant to ask following
    1. How will UL measure leakage current.?
    2. How will UL run the tests for single fault condition? How many single fault condition tests they got for this device?
    3. How do they determine ingress testing? what knid of methods will they use?
  5. [This followup was posted to and a copy was sent
    to the cited author.]

    Why don't you go to the horse's mouth and ask the UL these questions??
  6. Joerg

    Joerg Guest

    That might not fly for an ECG, since leakage under no-fault in some
    jurisdictions is expected to be <10uA. My copy of 60601 lists 10uA for
    no-fault and 50uA for S.F.C. for cat CF equipment. If you can get away
    with cat BF (I usually can't) maybe it's ok but ask UL about it.

    Personally I would never go above 10uA even if it was BF.
  7. Joerg

    Joerg Guest

    They measure it with DC and RMS meters et cetera. S.F.C. will usually be
    reviewed from schematics and then, for example, the PE connection is
    popped. And so on. They'll look at what could go wrong and test under
    that fault.

    Drip test, per IEC publication 529. But it depends on how you advertize
    the unit (outdoor use?). So it could either be drip, splash or
    watertightness tests.

    Anyhow, it looks like you seriously need help from an engineer who is
    familiar with this stuff.
  8. There's touch current too in the new standard.
    And Risk Management, ugh.

    Best to start with buying the standard(s) reading, and go to UL
    Universiity and take the courses. Or get a consultant.
    This is not a individual task, but a company task.

  9. Joerg

    Joerg Guest

    Same as in all EN standards. Sometimes I have the feeling that the paper
    industry had a hand in the 2012 changes :)

    Yup. And make sure the engineers read it, all of it. Because if you
    don't design with 60601 always in the back of your mind it is highly
    likely to fail. Just like one has to do it when branching into other
    industries. Before getting onto my first aerospace design I read
    RTCA/DO-160 several times cover to cover, on my own time.
  10. boB

    boB Guest

    You should purchase the necessary specification, UL or otherwise. It
    may also require other specs such as UL 1998.

    You may also want to consider another NRTL besides UL, like, Intertek
    (ETL) or CSA or TUV or whoever else can test the product because UL
    does not always follow the test spec.

    Are there any FDA requirements as well ?

  11. whit3rd

    whit3rd Guest

    Boy, do you EVER need advice. Pick one of these 60601-1 variants, and
    ignore the rest. And don't ask on the internet what the testing
    is, read the appropriate standard (and appendices)= that standard
    document IS THE ONLY SOURCE of information you can rely on.

    Various agencies adopt and cross-adopt versions of the evolving
    standard from time to time; you've indicated you want to check
    your design against four different snapshots of the SAME STANDARD,
    which will multiply your certificatioin requirements unreasonably.
  12. Guest

    1. I tried to read the standards. The thing is that I need some time to getfamiliar with the way these standards have been written. In the meantime, I was hoping that someone can guide me to the easy to understand explanations or material about single fault condition or leakage current testing.

    2. For example, I am using plastic enclosuer with DC battery ( No battery charger connected at all). Now, the standard talks about leakage currents orsingle fault conditions with enclosuers tied to earth. My enclosuer is nottied to earth at all. The standard does not have any example covering my device.

    3. I do not understand that why UL will have problems with their own approved charger. The leakage current is 0.1mA as mentioned in its data sheet. Ican not find any IEC and UL approved charger with lower leakage current. How will I explain this issue to UL if they come back to me saying that charger is no good. Though if user plugs in the charger , the unit will disableitself and nothing can be done.
  13. Joerg

    Joerg Guest

    Your ground return to human skin is not through the enclosure but
    through ECG electrodes.

    You don't know that yet. It all depends on what your ECG unit will be
    categorized as. If cat CF then they will likely not bless an assembly
    with this charger. Have you thought about the category? I believe that
    should be the first action item here.

    When UL approves something this does not mean it is approved for all
    kinds of uses.

    That's why we always design our own iso barriers for anything with
    cardiac or skin contact :)

    But the user can still do that while the ECG electrodes are connected to
    his/her skin, wondering why the thing doesn't work. Meaning the risk
    isn't 100% mitigated by a SW disable upon charger connection.

    Another issue, speaking from experience here: If the charger DC plug is
    a fairly common version users will try to cheat when they lose or damage
    the charger that came with your unit. They may by one from a local
    thrift store, plug it in, and "Hey, it works!".

    IMHO there needs to be a full isolation inside the ECG unit. I always
    make mine cat CF and also defibrillator-proof.
  14. Fred Abse

    Fred Abse Guest

    I hope that you are more proficient in understanding compliance standards
    than you appeared to be in understanding inductance, resonance, and
    Helmholz coils, a year or more ago.
  15. Guest

    Well, I had to stop because of FEMM. I am still trying to understand FEMM.
  16. Fred Abse

    Fred Abse Guest

    You don't need FEMM, at least not yet. What you do need is a good basic
    grounding in electrical theory. Sophomore level.
  17. Guest

    Your ground return to human skin is not through the enclosure but
    So, UL will short all the inputs of the ADS1298 to ground ( Data sheet:

    and measure the leakage current. Am I right?

    I am using ADS1298 to digitize the ECG signal.
  18. Joerg

    Joerg Guest

    Normally that's how it's done.

  19. There is only one 60601-1 standard now, it's the 3rd Edition.
    He can pick a varianat suchas IEC or AMMI, but its still 3rd Ed.
    Jun 30th was the last day anyone would accept 60601-1 2nd Ed

  20. Guest

    The thing is that OSHA does not recongnize 2nd edition.
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