Re: [PSES] [EXTERNAL] [PSES] Touch temperature limits for accessible parts
Dear Ted, Appreciate your view & advice! The charger with a detachable cable is normally left in the cigarette socket from day one. The user will use it when in the car or battery low of mobile phone (common object to be charged). As per charging protocol, the most likely full load would happen when the battery is at very low level. Then the charging current will decrease gradually. The chance of full load would be in a short period of time like your driving speed example. Probably I need to assess the risk of burn and possibilities of reducing the max temp. Regards, Scott On Fri, 3 Sept 2021 at 00:36, Ted Eckert wrote: > Hello Scott, > > > > IEC 62368-1 clause 3.3.7.4 defines “normal operating condition” as the > “mode of operation that represents as closely as possible the range of > normal use that can be reasonably expected”. It specifies the range of > possible uses, not the “typical” use. Note 1 for the clause makes it clear > that the most unfavorable default conditions must be considered for normal > use. > > > > If your charger is permanently connected to the device that it is > charging, is it possible to load the device such that it continuously draws > the maximum power from the charger? If the charger has a connector, > allowing different loads to be connected, could the user charge a series of > devices, one after the other, keeping the charger at maximum power for an > extended time? “Normal” does not mean “likely” or “common”. “Normal” is > what is allowed and foreseeable. > > > > In the United States, a number of mountain and southwestern states have > freeway speed limits up to 80 miles per hour. The vast majority of cars in > the United States will never travel at 80 mph for extended periods. If you > did a survey, I would expect you to find that, on average, the typical > American car spends less than 0.1% of the time at 80 mph. However, > travelling continuously at that speed is allowed and possible, and a small > subset of drivers will drive at that speed regularly. It’s neither typical > nor common, but it is “normal” and must be considered a normal condition. > > > > Ted Eckert > > The opinions expressed are my own and do not necessarily reflect those of > my employer. > > > > *From:* Scott Xe > *Sent:* Thursday, September 2, 2021 8:02 AM > *To:* Ted Eckert > *Cc:* EMC-PSTC@LISTSERV.IEEE.ORG > *Subject:* Re: [EXTERNAL] [PSES] Touch temperature limits for accessible > parts > > > > Dear Ted, > > > > Many thanks for your good considerations! I need to re-assess this issue > inclusive of those conditions. I have one conflicted point about the touch > temperature of 80 degC which is at full load. As you may know it, the full > load may happen at the initial charging and the charging current will > gradually decrease. In general, it may not be so hot in normal > conditions. What is your view on this? > > > > Kindest regards, > > > > Scott > > > > On Thu, 2 Sept 2021 at 21:43, Ted Eckert wrote: > > Hello Scott, > > > > Touch temperatures are measured at an ambient of 25 C. However, there are > a number of additional considerations. > >- What are normal operating conditions? Is it true that the user would >never touch the charger while it is in operation? There is no chance that >they would try to disconnected it from the car’s socket while it is at >maximum temperature? >- If the user could disconnect it, how long do they need to hold it to >pull it out of the car’s socket? Consider all users. For example, somebody >with arthritis and a poor grip might need more time to disconnect the >charger. >- Think about how TS2 limits apply to touch temperatures. What are the >abnormal and fault conditions? >- Even if the standard would only require testing at 25 C, you need to >consider that a car charger will be used at much higher ambient >temperatures. Have you done a hazard analysis based on the specific use of >this device? >- Will elevated temperatures on the charger result in customer >complaints? If the charger gets very hot, will it be perceived as unsafe? > > > > Ted Eckert > > The opinions expressed are my own and do not necessarily reflect those of > my employer, TC 108 or the Society of Automotive Engineers. > > > > *From:* Scott Xe > *Sent:* Thursday, September 2, 2021 6:02 AM > *To:* EMC-PSTC@LISTSERV.IEEE.ORG > *Subject:* [EXTERNAL] [PSES] Touch temperature limits for accessible parts > > > > I am looking for advice on temp measurements and the requirements. I have > an in-car charger with a temp of 80 degC on external plastic enclosure at > max load.
Re: [PSES] [EXTERNAL] [PSES] Touch temperature limits for accessible parts
Hello Scott, IEC 62368-1 clause 3.3.7.4 defines "normal operating condition" as the "mode of operation that represents as closely as possible the range of normal use that can be reasonably expected". It specifies the range of possible uses, not the "typical" use. Note 1 for the clause makes it clear that the most unfavorable default conditions must be considered for normal use. If your charger is permanently connected to the device that it is charging, is it possible to load the device such that it continuously draws the maximum power from the charger? If the charger has a connector, allowing different loads to be connected, could the user charge a series of devices, one after the other, keeping the charger at maximum power for an extended time? "Normal" does not mean "likely" or "common". "Normal" is what is allowed and foreseeable. In the United States, a number of mountain and southwestern states have freeway speed limits up to 80 miles per hour. The vast majority of cars in the United States will never travel at 80 mph for extended periods. If you did a survey, I would expect you to find that, on average, the typical American car spends less than 0.1% of the time at 80 mph. However, travelling continuously at that speed is allowed and possible, and a small subset of drivers will drive at that speed regularly. It's neither typical nor common, but it is "normal" and must be considered a normal condition. Ted Eckert The opinions expressed are my own and do not necessarily reflect those of my employer. From: Scott Xe Sent: Thursday, September 2, 2021 8:02 AM To: Ted Eckert Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [EXTERNAL] [PSES] Touch temperature limits for accessible parts Dear Ted, Many thanks for your good considerations! I need to re-assess this issue inclusive of those conditions. I have one conflicted point about the touch temperature of 80 degC which is at full load. As you may know it, the full load may happen at the initial charging and the charging current will gradually decrease. In general, it may not be so hot in normal conditions. What is your view on this? Kindest regards, Scott On Thu, 2 Sept 2021 at 21:43, Ted Eckert mailto:ted.eck...@microsoft.com>> wrote: Hello Scott, Touch temperatures are measured at an ambient of 25 C. However, there are a number of additional considerations. * What are normal operating conditions? Is it true that the user would never touch the charger while it is in operation? There is no chance that they would try to disconnected it from the car's socket while it is at maximum temperature? * If the user could disconnect it, how long do they need to hold it to pull it out of the car's socket? Consider all users. For example, somebody with arthritis and a poor grip might need more time to disconnect the charger. * Think about how TS2 limits apply to touch temperatures. What are the abnormal and fault conditions? * Even if the standard would only require testing at 25 C, you need to consider that a car charger will be used at much higher ambient temperatures. Have you done a hazard analysis based on the specific use of this device? * Will elevated temperatures on the charger result in customer complaints? If the charger gets very hot, will it be perceived as unsafe? Ted Eckert The opinions expressed are my own and do not necessarily reflect those of my employer, TC 108 or the Society of Automotive Engineers. From: Scott Xe mailto:scott...@gmail.com>> Sent: Thursday, September 2, 2021 6:02 AM To: EMC-PSTC@LISTSERV.IEEE.ORG<mailto:EMC-PSTC@LISTSERV.IEEE.ORG> Subject: [EXTERNAL] [PSES] Touch temperature limits for accessible parts I am looking for advice on temp measurements and the requirements. I have an in-car charger with a temp of 80 degC on external plastic enclosure at max load. Referring to EN 62368-1, the max temp is from 48 - 94 degC depending on the time to be touched to operate the equipment. During operation, it is unnecessary to touch the external enclosure except plugging in and taking out from cigarette socket. Is it deemed to apply 94 degC? Should the max temp be measured at room temp of 25 degC or the maximum operating temp? If at max operating temp, how to derive the max temp limits in such conditions? Thanks and regards, Scott - 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 mailto:emc-p...@ieee.org>> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html<https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.ieee-pses.org%2Femc-pstc.html=04%7C01%7CTed.Eckert%40microsoft.com%7
Re: [PSES] [EXTERNAL] [PSES] Touch temperature limits for accessible parts
Dear Ted, Many thanks for your good considerations! I need to re-assess this issue inclusive of those conditions. I have one conflicted point about the touch temperature of 80 degC which is at full load. As you may know it, the full load may happen at the initial charging and the charging current will gradually decrease. In general, it may not be so hot in normal conditions. What is your view on this? Kindest regards, Scott On Thu, 2 Sept 2021 at 21:43, Ted Eckert wrote: > Hello Scott, > > > > Touch temperatures are measured at an ambient of 25 C. However, there are > a number of additional considerations. > >- What are normal operating conditions? Is it true that the user would >never touch the charger while it is in operation? There is no chance that >they would try to disconnected it from the car’s socket while it is at >maximum temperature? >- If the user could disconnect it, how long do they need to hold it to >pull it out of the car’s socket? Consider all users. For example, somebody >with arthritis and a poor grip might need more time to disconnect the >charger. >- Think about how TS2 limits apply to touch temperatures. What are the >abnormal and fault conditions? >- Even if the standard would only require testing at 25 C, you need to >consider that a car charger will be used at much higher ambient >temperatures. Have you done a hazard analysis based on the specific use of >this device? >- Will elevated temperatures on the charger result in customer >complaints? If the charger gets very hot, will it be perceived as unsafe? > > > > Ted Eckert > > The opinions expressed are my own and do not necessarily reflect those of > my employer, TC 108 or the Society of Automotive Engineers. > > > > *From:* Scott Xe > *Sent:* Thursday, September 2, 2021 6:02 AM > *To:* EMC-PSTC@LISTSERV.IEEE.ORG > *Subject:* [EXTERNAL] [PSES] Touch temperature limits for accessible parts > > > > I am looking for advice on temp measurements and the requirements. I have > an in-car charger with a temp of 80 degC on external plastic enclosure at > max load. Referring to EN 62368-1, the max temp is from 48 - 94 degC > depending on the time to be touched to operate the equipment. During > operation, it is unnecessary to touch the external enclosure except > plugging in and taking out from cigarette socket. Is it deemed to apply 94 > degC? > > > > Should the max temp be measured at room temp of 25 degC or the maximum > operating temp? If at max operating temp, how to derive the max temp > limits in such conditions? > > > > Thanks and regards, > > > > Scott > > - > > > 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 > <https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.ieee-pses.org%2Femc-pstc.html=04%7C01%7Cted.eckert%40microsoft.com%7Cdaf42692ba0b4d76419b08d96e11efea%7C72f988bf86f141af91ab2d7cd011db47%7C0%7C0%7C637661845595660774%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000=JT5tQ24VSauqNvCtgLYHXBfQkqJJQg5DFvTOudX2qr4%3D=0> > > Attachments are not permitted but the IEEE PSES Online Communities site at > http://product-compliance.oc.ieee.org/ > <https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fproduct-compliance.oc.ieee.org%2F=04%7C01%7Cted.eckert%40microsoft.com%7Cdaf42692ba0b4d76419b08d96e11efea%7C72f988bf86f141af91ab2d7cd011db47%7C0%7C0%7C637661845595670768%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000=nXDOxksTgeLxo5OmXNendXphqDu0THfjQ4uLvNH%2F%2Bos%3D=0> > can be used for graphics (in well-used formats), large files, etc. > > Website: http://www.ieee-pses.org/ > <https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.ieee-pses.org%2F=04%7C01%7Cted.eckert%40microsoft.com%7Cdaf42692ba0b4d76419b08d96e11efea%7C72f988bf86f141af91ab2d7cd011db47%7C0%7C0%7C637661845595680764%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000=3hXM%2FQLSgv1tBcTP4lB%2BxGXZmyYV5V3P503wdhzKqFg%3D=0> > Instructions: http://www.ieee-pses.org/list.html (including how to > unsubscribe) > <https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.ieee-pses.org%2Flist.html=04%7C01%7Cted.eckert%40microsoft.com%7Cdaf42692ba0b4d76419b08d96e11efea%7C72f988bf86f141af91ab2d7cd011db47%7C0%7C0%7C637661845595680764%7CUnknown%7CTWF
Re: [PSES] [EXTERNAL] [PSES] Touch temperature limits for accessible parts
Hello Scott, Touch temperatures are measured at an ambient of 25 C. However, there are a number of additional considerations. * What are normal operating conditions? Is it true that the user would never touch the charger while it is in operation? There is no chance that they would try to disconnected it from the car's socket while it is at maximum temperature? * If the user could disconnect it, how long do they need to hold it to pull it out of the car's socket? Consider all users. For example, somebody with arthritis and a poor grip might need more time to disconnect the charger. * Think about how TS2 limits apply to touch temperatures. What are the abnormal and fault conditions? * Even if the standard would only require testing at 25 C, you need to consider that a car charger will be used at much higher ambient temperatures. Have you done a hazard analysis based on the specific use of this device? * Will elevated temperatures on the charger result in customer complaints? If the charger gets very hot, will it be perceived as unsafe? Ted Eckert The opinions expressed are my own and do not necessarily reflect those of my employer, TC 108 or the Society of Automotive Engineers. From: Scott Xe Sent: Thursday, September 2, 2021 6:02 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [EXTERNAL] [PSES] Touch temperature limits for accessible parts I am looking for advice on temp measurements and the requirements. I have an in-car charger with a temp of 80 degC on external plastic enclosure at max load. Referring to EN 62368-1, the max temp is from 48 - 94 degC depending on the time to be touched to operate the equipment. During operation, it is unnecessary to touch the external enclosure except plugging in and taking out from cigarette socket. Is it deemed to apply 94 degC? Should the max temp be measured at room temp of 25 degC or the maximum operating temp? If at max operating temp, how to derive the max temp limits in such conditions? Thanks and regards, Scott - 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 mailto:emc-p...@ieee.org>> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html<https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.ieee-pses.org%2Femc-pstc.html=04%7C01%7Cted.eckert%40microsoft.com%7Cdaf42692ba0b4d76419b08d96e11efea%7C72f988bf86f141af91ab2d7cd011db47%7C0%7C0%7C637661845595660774%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000=JT5tQ24VSauqNvCtgLYHXBfQkqJJQg5DFvTOudX2qr4%3D=0> Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/<https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fproduct-compliance.oc.ieee.org%2F=04%7C01%7Cted.eckert%40microsoft.com%7Cdaf42692ba0b4d76419b08d96e11efea%7C72f988bf86f141af91ab2d7cd011db47%7C0%7C0%7C637661845595670768%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000=nXDOxksTgeLxo5OmXNendXphqDu0THfjQ4uLvNH%2F%2Bos%3D=0> can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/<https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.ieee-pses.org%2F=04%7C01%7Cted.eckert%40microsoft.com%7Cdaf42692ba0b4d76419b08d96e11efea%7C72f988bf86f141af91ab2d7cd011db47%7C0%7C0%7C637661845595680764%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000=3hXM%2FQLSgv1tBcTP4lB%2BxGXZmyYV5V3P503wdhzKqFg%3D=0> Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe)<https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.ieee-pses.org%2Flist.html=04%7C01%7Cted.eckert%40microsoft.com%7Cdaf42692ba0b4d76419b08d96e11efea%7C72f988bf86f141af91ab2d7cd011db47%7C0%7C0%7C637661845595680764%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000=N3BWwmAmy%2FnjEKoC5lzgusYQBa%2BSuRMN50SXJ7ggXvA%3D=0> List rules: http://www.ieee-pses.org/listrules.html<https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.ieee-pses.org%2Flistrules.html=04%7C01%7Cted.eckert%40microsoft.com%7Cdaf42692ba0b4d76419b08d96e11efea%7C72f988bf86f141af91ab2d7cd011db47%7C0%7C0%7C637661845595690760%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000=b9bWTmL3dLHF9wJT4ehWrYZ733gLUV2CxOJUxSpHjD8%3D=0> For help, send mail to the list administrators: Scott Douglas mailto:sdoug...@ieee.org>> Mike Cantwell mailto:mcantw...@ieee.org>> For policy questions, send mail to: Jim Bacher mailto:j.bac...@ieee.org>> David Heald mailto:dhe...@gmail.com>> - --
