Yes, of course, but the SOD (standards development organizations) like UL, ANSI, CSA, and IEC, work closely with the manufacturer of those components to establish useful limits. As John points out, a temperature limit to the closest 5 Celsius degrees is likely the smallest, practicable step-size and fit for purpose.
Ralph From: sudhakar wasnik <[email protected]> Sent: Thursday, August 29, 2024 2:07 PM To: [email protected] Cc: EMC-PSTC <[email protected]> Subject: Re: [PSES] [PSES] IEC62368-1 - Abnormal condition - Fail Agencies like UL, CSA, TUV etc…. aren’t the agencies responsible for approving components like capacitors, switches, cables , transformers , fuses etc? >From the component manufacturer’s point of view, parameters have tolerances >like temperature, If it’s data sheet has tolerance in terms of % or values , >It can be explained to certification agencies. This is quite common usually with power supply manufacturers… .claims all certifications, however when it is installed in end products… the same power supply may have different thermal outcome And this will have to be resolved by end user under normal , abnormal, single fault conditions … Hope this helps, Sudhakar On Aug 29, 2024, at 1:24 PM, Ralph McDiarmid <[email protected] <mailto:[email protected]> > wrote: “approved” by whom, the manufacturer ? They would be better able to determine that limit and it would be based on reliability analysis. The 5-degree increment is an interesting point, whoever, just about any component you choose seems to have a temperature limit that is a multiple of 5 degrees C. (circuit boards, transistors, electrolytic capacitors, insulated wire, recognized insulation systems). Everything rounded to the closest 5 degrees perhaps. Ralph From: Richard Nute <[email protected] <mailto:[email protected]> > Sent: Thursday, August 29, 2024 12:17 PM To: [email protected] <mailto:[email protected]> Subject: Re: [PSES] SV: [PSES] IEC62368-1 - Abnormal condition - Fail Hi John: I disagree. We don’t know the temperature for failure. We don’t know the difference between the “approved” temperature and the failure temperature. Indeed, we seldom test for failure temperature. All we can say is that at 85 C, the part should work for the product lifetime. Above this temperature, the part may work for the product lifetime, or it may fail before the product lifetime. Ideally, the end product should be like the “one-hoss shay.” https://www.youtube.com/watch?v=wiOHhhwnK6k And, the “approved” temperature is 85 C, which is an arbitrary assignment. If it was not arbitrary, I would have expected the “approved” temperature to be 83, 84, or 86 or some number other than 5 degree increments. 😊 Best regards, Rich From: John Woodgate <[email protected] <mailto:[email protected]> > Sent: Thursday, August 29, 2024 11:35 AM To: [email protected] <mailto:[email protected]> Subject: Re: [PSES] SV: [PSES] IEC62368-1 - Abnormal condition - Fail But that component is not likely to be very reliable, if its temperature under normal conditions is close to the maximum permitted. On 2024-08-29 19:04, Amund Westin wrote: 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] <mailto:[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 <http://www.unit3compliance.co.uk/> www.unit3compliance.co.uk | <mailto:[email protected]> [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] <mailto:[email protected]> or call 01274 911747. Our lead times for testing and consultancy are typically 4-5 weeks. From: Charlie Blackham <[email protected] <mailto:[email protected]> > Sent: 29 August 2024 17:19 To: [email protected] <mailto:[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) <image001.png> Best regards Charlie Charlie Blackham Sulis Consultants Ltd Tel: +44 (0)7946 624317 Web: https://sulisconsultants.com/ Registered in England and Wales, number 05466247 From: Amund Westin <[email protected] <mailto:[email protected]> > Sent: 29 August 2024 17:07 To: [email protected] <mailto:[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: 1. Product installed by skilled and trained technical persons. 2. 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 _____ This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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