LED assembly typically powered by CC source (essentially DC), so should be no mains-frequency flicker. There are some dimming schemes using constant freq/variable duty cycle, but the unless the off period is very long, freq should be too high for persistency of human vision.
The cheaper drivers are typically single-stage flybacks with current FB only, so some have EMI problems. Brian -----Original Message----- From: Ralph McDiarmid [mailto:ralph.mcdiar...@schneider-electric.com] Sent: Wednesday, June 22, 2016 3:06 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] AMA Warns of Harm from LED Streetlights’ Blue Light This seems a reasonable idea, in an attempt to approximate the intensity of existing lamps. ( turn 'em down a little! ) "The AMA recommends an intensity threshold for optimal LED lighting that minimizes blue-rich light" Depending on how these things are powered, I wonder if there might be a flicker problem at 50Hz? (similar to the CRT television frame rate flicker that was so noticeable to those of us used to the 60Hz rate) Ralph McDiarmid Product Compliance Engineering Solar Business Schneider Electric -----Original Message----- From: Richard Nute [mailto:ri...@ieee.org] Sent: Wednesday, June 22, 2016 1:07 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] AMA Warns of Harm from LED Streetlights’ Blue Light Thanks for the URL to the AMA website. Unfortunately, the AMA doesn't give any color temperature or intensity numbers for "harmful human and environmental effects of high intensity street lighting." So, how are we to know what is acceptable to the AMA? As safety engineers, we cannot design a suitable safeguard without these numbers. How do the AMA numbers (if any) compare with sunlight, the defacto standard? We have an old fluorescent backlight TV in our bedroom that we watch at night before we fall asleep. Is this any different light than a tablet or laptop allegedly causing insomnia? (Or is it the use of the tablet or laptop that causes the insomnia?) The TV display does not cause us insomnia, as far as I know, while the content often does. Here is a treatise on color temperature: http://www.feit.com/color-temperature Rich - ---------------------------------------------------------------- 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 Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <sdoug...@ieee.org> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com> ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. ______________________________________________________________________ ________________________________ This message was scanned by Exchange Online Protection Services. ________________________________ - ---------------------------------------------------------------- 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 Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <sdoug...@ieee.org> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com> - ---------------------------------------------------------------- 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 Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <sdoug...@ieee.org> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
