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 <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 <scott...@gmail.com> > *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. 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