I wondered if anyone had any guidance or insight on the UL ratings for maximum allowable ratings for laptop power adapters. I've done a considerable amount of research, including reading the numerous articles on this website which have been immensely helpful. I read the updated article (referenced below), and from what I can tell, my particular adapter was made by Delta Electronics, and the certification is held through UL in Canada, UL#E131881 for PSU ADP-65HB BC (link also below). I am also attaching photos of my PSU for reference so you can see where I am obtaining the numbers from. This was a factory HP laptop, Pavilion dm4, and the adapter was made by Delta Electronics and came supplied with the laptop by the manufacturer.
The questions I have are more in regards to general UL Standards and electrical industry standards when it comes to allowable heat/temperature touch maximums. The UL site and tests are somewhat difficult to decipher, but from the best I've been able to tell so far, the UL sets the maximum allowable temperature for a component such as this one, (a laptop power adapter)at 75C (167 F) which seems unreasonably high to me considering I set my oven at 170 degrees F on the 'keep warm' setting. Even so, I must have read through 30 or 40 UL tests from various PSU manufacturers which were conducted to have a surface temperature no greater than 40 degrees C at the most (temperatures varied between devices and manufactures) which is about 105 degrees.
The adapter I have is measuring at 150 degrees F (internally 160), and is getting that hot from being powered off in about 2 hours at I’d guess about 40% capacity. I’m measuring at that with a recently calibrated Fluke 52 II and FLIR E60.
I guess what I’m wondering is if anyone knows whether most of the companies have their own set of standards that go unpublished as far as the maximum surface temperature limits for the adapters when they do their testing? In other words, if the maximum “UL Standard Limit” is 167 degrees F/75 C, why don’t I see the tests being conducted on the units with those limits, if that makes sense? Why are the tests being conducted with limits no higher than 40 C?
Any insight or comments would be very much appreciated. Thank you!!
http://www.tomshardware.com/reviews/how-we-test-psu,4042.html#p13
http://database.ul.com/cgi-bin/XYV/template/LISEXT/1FRAME/showpage.html?name=QQGQ7.E131881&ccnshorttitle=Power+Supplies,+Information+Technology+Equipment+Including+Electrical+Business+Equipment+Certified+for+Canada&objid=1074197053&cfgid=1073741824&version=versionless&parent_id=1073992441&sequence=1
The questions I have are more in regards to general UL Standards and electrical industry standards when it comes to allowable heat/temperature touch maximums. The UL site and tests are somewhat difficult to decipher, but from the best I've been able to tell so far, the UL sets the maximum allowable temperature for a component such as this one, (a laptop power adapter)at 75C (167 F) which seems unreasonably high to me considering I set my oven at 170 degrees F on the 'keep warm' setting. Even so, I must have read through 30 or 40 UL tests from various PSU manufacturers which were conducted to have a surface temperature no greater than 40 degrees C at the most (temperatures varied between devices and manufactures) which is about 105 degrees.
The adapter I have is measuring at 150 degrees F (internally 160), and is getting that hot from being powered off in about 2 hours at I’d guess about 40% capacity. I’m measuring at that with a recently calibrated Fluke 52 II and FLIR E60.
I guess what I’m wondering is if anyone knows whether most of the companies have their own set of standards that go unpublished as far as the maximum surface temperature limits for the adapters when they do their testing? In other words, if the maximum “UL Standard Limit” is 167 degrees F/75 C, why don’t I see the tests being conducted on the units with those limits, if that makes sense? Why are the tests being conducted with limits no higher than 40 C?
Any insight or comments would be very much appreciated. Thank you!!
http://www.tomshardware.com/reviews/how-we-test-psu,4042.html#p13
http://database.ul.com/cgi-bin/XYV/template/LISEXT/1FRAME/showpage.html?name=QQGQ7.E131881&ccnshorttitle=Power+Supplies,+Information+Technology+Equipment+Including+Electrical+Business+Equipment+Certified+for+Canada&objid=1074197053&cfgid=1073741824&version=versionless&parent_id=1073992441&sequence=1
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