Perhaps Amund could ask the lab which clause in IEC 62368 supports
their statement, “ _The standard also does not accept that critical
components get a temperature above what is specified in the test
report for that component». “_
_ _
This is an Abnormal Condition and safeguard parameters, which include
rated temperature, are not subject to the same constraints imposed
during Normal Condition.
_ _
I suggest there are two problems here. One is that the lab seems to
misunderstand Abnormal Condition and the other is terminology like
_Basic Safeguard Parameters_ and _Supplementary Safeguard Parameters_
used in Figure 45 do not seem to be defined anywhere.
_ _
_Ralph_
From: Richard Nute <[email protected]>
Sent: Monday, September 2, 2024 12:54 PM
To: [email protected]; [email protected]
Subject: RE: [PSES] SV: [PSES] SV: [PSES] SV: [PSES] IEC62368-1 -
Abnormal condition - Fail
Further to Ralph’s comments… and with thanks to Amund…
Since the lab has its own interpretation of “abnormal” different
than that of 62368-2, the lab needs to make its position on
“abnormal” conditions known and apply to TC108 for consideration
of a change to 62368-2.
Or, Amund can forward the lab’s interpretation directly to TC108,
although this will probably go to the interpretation panel.
Rich
ps: The lab’s response does make sense – sort of. It is filled
with “what ifs” that I have some doubt that the assertions are
from the lab’s experience. For example, for the exterior of the
module to reach 85 C, the interior has to be hotter (maybe much
hotter) and may exceed solid insulation rated temperature. We and the
lab don’t know, but at 85 C, we (us) assume the interior solid
insulation (and other safeguards) does not exceed its rating (which
must be greater than 85 C).
Another statement that creates doubt for me is that “_also lead to
other dangers such as mains voltage being absorbed_.” The lab does
not know what the “_other dangers_” are, and leaves us up in the
air about what is “_mains voltage being absorbed_…” Absorbed by
what?
rn
From: Ralph McDiarmid <[email protected]>
Sent: Monday, September 2, 2024 9:52 AM
To: [email protected]
Subject: Re: [PSES] SV: [PSES] SV: [PSES] SV: [PSES] IEC62368-1 -
Abnormal condition - Fail
To add to what Charlie has mentioned, the integrity of a _safeguard_,
like protective separation, can be verified at the end of the Abnormal
with a dielectric test. A satisfactory result would indicate that the
_safeguard_ remains effective. The standard states that _safeguard_
parameters, like rated temperature, can be exceeded during an abnormal
test.
If your lab doesn’t agree with any of this, I suggest you check to
see if they are accredited to perform test and evaluation for IEC
62368. The lab may not be able to comprehend and interpret a complex
standard like 62368.
Ralph
From: Charlie Blackham <[email protected]>
Sent: Monday, September 2, 2024 1:28 AM
To: [email protected]
Subject: Re: [PSES] SV: [PSES] SV: [PSES] SV: [PSES] IEC62368-1 -
Abnormal condition - Fail
Amund
A safety critical component rated at 85C is rated to run safely at
that temperature for the life of the product.
The temperature is only exceeded under an abnormal condition, which by
definition is not a normal operating condition:
3.3.7.1
abnormal operating condition
temporary operating condition that is not a normal operating condition
and is not a single fault condition of the equipment itself
a component providing ES3 to ES1 isolation has double or reinforced
insulation, so remains safe even in a single fault condition, which
we’re not assessing here.
It looks like the lab doesn’t properly understand clauses B.3 and
B.4 and I’ve never seen a competent lab use “bad luck” in a
report before 😊
Best regards
Charlie
Charlie Blackham
Sulis Consultants Ltd
Tel: +44 (0)7946 624317
Web: https://sulisconsultants.com/ [1]
Registered in England and Wales, number 05466247
From: Amund Westin <[email protected]>
Sent: 02 September 2024 09:02
To: [email protected]
Subject: [PSES] SV: [PSES] SV: [PSES] SV: [PSES] IEC62368-1 - Abnormal
condition - Fail
Hello Rich
The component that gets hot, is a DC/DC module, bought from a
well-known manufacturer and the module holds a CB certificate.
Module Spec is +85C, when it reaches +89C, the final product itself
shouts down as a consequence to too high temperature.
The lab answer as follow:
_«What fails here is that a very critical component gets too hot.
What makes this component so critical is that this component is used
as a separation between primary to secondary circuits (So ES3 -> ES1).
As the module again has critical components in it (such as a
transformer) which are in the separator, we have no control over how
hot this component gets as it has only been tested up to 85oC. If the
component gets too hot, this can cause the separation to be broken and
you will then get primary voltage (ES3) into the secondary circuit
(which is ES1)._
_This can also lead to other dangers such as mains voltage being
absorbed in the event of bad luck or a fire. (This can also spread out
of the product, if other products are connected via e.g. the RS232
connector). The standard also does not accept that critical components
get a temperature above what is specified in the test report for that
component»._
Does it make sense?
Regards
Amund
Fra: Richard Nute
Sendt: 30. august 2024 22:37
Til: [email protected]
Emne: Re: [PSES] SV: [PSES] SV: [PSES] IEC62368-1 - Abnormal condition
- Fail
Hello Amund:
Did you point out to the lab the relevant sub-clauses of 62368-2 per
Charlie Blackham? If so, what was their reply (i.e., what safeguard
failed)?
Good luck,
Rich
From: Amund Westin <[email protected]>
Sent: Friday, August 30, 2024 5:15 AM
To: [email protected]
Subject: [PSES] SV: [PSES] SV: [PSES] IEC62368-1 - Abnormal condition
- Fail
Under abnormal condition (holes in the chassis are blocked), the
internal DC/DC module reach its maximum spec (+85C) and at +89C, the
product make a shutdown due to its own safety.
* No fire is generated.
* Hot module/component, yes, but not accessible for humans (inside
product)
* The module is located inside the fire enclosure.
* Nothing dangerous situation is generated, but product shuts down
due to too hot module. Product could (maybe) also get permanent
damaged, if the module broke down due to the heat.
Anyway, the product seems to be safe regarding to both fire safety and
electrical hazard. Isn’t that what it’s all about? Safe product,
but maybe poor reliable if such Abnormal condition happens.
The lab does not agree with me.
BR Amund
Fra: Amund Westin
Sendt: 29. august 2024 20:05
Til: [email protected]
Emne: [PSES] SV: [PSES] IEC62368-1 - Abnormal condition - Fail
Thanks James,
No, the component that gets hot, but it is not accessible. It’s on a
pcb inside the metal enclosure. The temperature was measures to 87C.
The CB test report for the DC/DC component says it was tested and
approved up to 85C.
No ignition. The FAIL statement was due to higher temperature than
approved in CB report for the component.
Best regards Amund
Fra: James Pawson (U3C)
Sendt: 29. august 2024 18:35
Til: [email protected]
Emne: Re: [PSES] IEC62368-1 - Abnormal condition - Fail
Amund,
Is the temperature accessible?
Is there any ignition caused?
If no then the requirements have likely been met.
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 [2] | [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: Charlie Blackham <[email protected]>
Sent: 29 August 2024 17:19
To: [email protected]
Subject: Re: [PSES] IEC62368-1 - Abnormal condition - Fail
Amund
Basic safeguard parameters may be exceeded during abnormal condition
tested in Annex B.3.
B.3.8 Compliance criteria during and after abnormal operating
conditions
_During an abnormal operating condition that does not lead to a single
fault condition, all safeguards shall remain effective. After
restoration of normal operating conditions, all safeguards shall
comply with applicable requirements._
_ _
_If an abnormal operating condition leads to a consequential fault,
the compliance criteria of B.4.8 apply_
_ _
The following is provided in PD IEC TR 62368‑2:2019, Part 2:
Explanatory information related to IEC 62368-1:2018 (same in the 2014
version)
Best regards
Charlie
Charlie Blackham
Sulis Consultants Ltd
Tel: +44 (0)7946 624317
Web: https://sulisconsultants.com/ [1]
Registered in England and Wales, number 05466247
From: Amund Westin <[email protected]>
Sent: 29 August 2024 17:07
To: [email protected]
Subject: [PSES] IEC62368-1 - Abnormal condition - Fail
We measure a few degrees too high temperature on a power component
inside the product, when the ventilation holes in the chassis are
blocked (abnormal condition).
Draft verdict from test lab is FAIL.
Our claim is that such abnormal condition will not happen due to:
* Product installed by skilled and trained technical persons.
* Product installed in racks / environment that make it impossible
for such blocking.
The product is placed in closed premises with fences covering the
premises. It’s part of international aircraft navigation system.
Question:
Is it reasonable to require such an abnormal condition test, when that
a situation is not practical to happened in real life?
Thanks!
BR Amund Westin
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