I have been watching this subject for a while.
i vaguely recall that in some front matter in some standards is a statement
that indicates that this is the minimum requirements to go to market.
So in the interests of the Corp/s that I worked for at the time, and any
quality targets, that they may have, or not, regardless of their awareness of
such targets...
I often figured out tests that were needed/useful ... but maybe not required in
the strict minimum requirements.
And reported the results.
And fixes to meet those "not strictly required" minimum standards.
And did this early in the development process, thus EMC First,
First off product could ship !!!
And then I/they could spend time and money on cost reducing at our leisure.
Cuz product was shipping and bringing in revenue.
On time, or even early before plans.
On Thursday, May 9, 2024, 7:44:05 AM EDT, James Pawson (U3C)
<[email protected]> wrote:
Hi Piotr,
Just to add to the debate:
“I know that if circuit is not going out of building it is considered being
without transients”
If a cable is longer than 30m then most product EMC standards will call up a
requirement for line-to-earth surge testing. Some do make it explicit that this
should be only for cables leaving a building or site, some do not…
All the best
James
James Pawson
Managing Director & EMC Problem Solver
Unit 3 Compliance Ltd
EMC : Environmental & Vibration : Electrical Safety : CE & UKCA : Consultancy
www.unit3compliance.co.uk | [email protected]
+44(0)1274 911747 | +44(0)7811 139957
2 Wellington Business Park, New Lane, Bradford, BD4 8AL
Registered in England and Wales # 10574298
Office hours:
Every morning my full attention is on consultancy, testing, and troubleshooting
activities for our customers’ projects. I’m available/contactable between 1300h
to 1730h Mon/Tue/Thurs/Fri.
For inquiries, bookings, and testing updates please send us an email on
[email protected] or call 01274 911747. Our lead times for testing
and consultancy are typically 4-5 weeks.
From: Piotr Galka <[email protected]>
Sent: Wednesday, May 8, 2024 9:28 PM
To: [email protected]
Subject: Re: [PSES] IEC 62368-1: To understand chapter 5.4.11
Hi Bostjan,
I know that if circuit is not going out of building it is considered being
without transients. My doubt is mainly because in 5.4.11 says about circuits
being external and indicated in table 14 and according to my understanding
3.3.1.1 USB was external and note about transients in table 14 for me didn't
make for me USB being not indicated in table.
In my RS485 design even it is in one building I assume during storm up to 50V
temporary difference between several grounding points and I use 2 steps
protection. I know of two such incidents that after lightning struck directly
into the building, many systems stopped working, but ours did.
I acknowledge that USB is not external circuit.
Thanks a lot.
I have never bought any standard abroad and as I have written answering to
Johns post I see that 62368-2 is not in current Polish Standard Committee offer.
Best regards
Piotr Galka
W dniu 2024-05-08 o 18:45, Boštjan Glavič pisze:
Hi Piotr
If circuit does not go out of building it is not considered as circuit with
transients. I think you should check other standard like IEC 62151 and IEC
62102 which clasify external circuits.
>From my experiences, and I do have quite some, USB is not considered as
>external circuit in the sense of clause, where requirements between external
>circuit and PE are specified.
Did you also check 62368-2?
Best regards
Bostjan
Poslano iz Outlook za Android
Od: Piotr Galka <[email protected]>
Poslano: sreda, maj 8, 2024 5:21:33 PM
Za: [email protected] <[email protected]>
Zadeva: Re: [PSES] IEC 62368-1: To understand chapter 5.4.11
Hi Bostjan,
Thanks for your feedback, but...
I am slowly and carefully reading 62368-1 for the first time.
It defines 'external circuit' in 3.3.1.1 as "electrical circuit that is
external to the equipment and is not mains".
I assumed one device = one equipment so I thought laptop is an
equipment. After your post I checked how equipment is defined in 62368-1
but in 3.3 there is no equipment definition so I don't know what is
equipment.
May be USB device (pendrive) connected without cable to laptop can be
assumed being its part, or even device powered by USB (mouse, keyboard)
can be assumed being its part, but USB can be used to connect other
equipment, I think. Do laser printer being powered separately from mains
connected to laptop is understood as being internal part of equipment?
Laptop is probably manufactured by someone else than laser printer. They
can't assume they manufacture single equipment, I think.
In past I have read about USB being used to connect active wifi antenna
located on the roof (with few hubs to extend connection length). Having
all that in mind it is hard for me to accept that for 62368-1 USB is
equipment internal circuit.
Now.
If we assume laptop with connected to it mouse, external keyboard and
printer is one equipment then going to my field: do the access control
controller with RFID readers connected to it by RS485 is also one
equipment (all powered from one 12V supply, and located in one building)
making RS485 connection being internal equipment circuit?
I don't think so.
And I repeat my main question regarding 5.4.11: Do the access controller
permanently connected to 12V supply that is permanently connected to
mains is permanently connected equipment? I think yes. Even 12V supply
has isolation in it.
If I change understanding of equipment and assume that controller + 12V
supply are one equipment than thinks get easier - such understood
equipment is permanently connected. But is it one equipment if
controller is manufactured by someone other then 12V supply.
Best regards
Piotr Galka
W dniu 2024-05-07 o 19:49, Boštjan Glavič pisze:
> Hi Piotr
>
> USB circuit is internal circuit. There are no transients expected on USB.
> Clause 5.4.11 is not applicable for power supply with USB output.
>
> Paired conductor is a telecommunication network that we had in old times
> (analogue network, ISDN,...).
>
> I hope this helps. If you need more info, you can contact me.
>
> Best regards,
> Boštjan
>
>
>
> -----Original Message-----
> From: Piotr Galka <[email protected]>
> Sent: Tuesday, May 7, 2024 5:40 PM
> To: [email protected]
> Subject: [PSES] IEC 62368-1: To understand chapter 5.4.11
>
> CAUTION: This email originated from outside of our organisation. Do not click
> links or open attachments unless you recognise the sender and know the
> content is safe.
>
>
> Trying to understand 62368-1...
>
> I have got laptop with type A power supply so it looks being not excluded
> from 5.4.11 by rules in 5.4.11.1.
> For me USB are external circuits indicated in Table 14, ID numbers 1 and
> 2 (I think USB is 'Paired conductor', but even not it certainly is 'Any other
> conductors').
> The note in Table 14 about not taking into account transients for external
> circuits installed wholly within the same building is only about transients
> so I think it doesn't make USB being not indicated in table.
> USB cable can be used to connect laptop to printer and in printer USB can be
> earthed, I think.
> Dos this means that according to first sentence of 5.4.11.2 each USB port in
> this laptop should be separated from its other USB ports?
> I don't believe there is such requirement.
>
> My real problem to understand is as follows:
> Typical access controller have several not separated from each other inputs
> (several RFID reader inputs, door state control input, tamper inputs and
> others).
> I need to understand if the access controller powered from (external to
> it) 12V DC buffered (= having accu in it) supply is permanently connected
> equipment or not?
> To disconnect it from 12V supply you need tools, to disconnect 12V supply
> from mains you need tools, but 12V supply has isolation in it so access
> controller is not electrically connected to mains and 3.3.3.4 says about
> needing tools to disconnect from mains (if something is not connected than
> tools are not needed to make it being disconnected, I think).
> Being permanently connected equipment is the easiest way for controller to be
> excluded from 5.4.11.
> But if it is not permanently connected than its inputs are in the same
> situation as laptop USB ports I described first as more common to everyone.
>
> What I miss or wrongly understand?
>
> Regards
> Piotr Galka
>
> P.S.
> Last month free time I spend browsing about 2800 EMC-PSTC posts collected by
> my mail program for few years.
>
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