Dear Group,
I understand that maintaining the L-N orientation is regarded as 'good practice' however I cannot find any hard requirement in UL60950 and would like to know the source. We manufacture several 1U high ITE products in the 20-40W range which use several different models of open frame auto-ranging AC power supplies. (100-240VAC to 12VDC). We use a short two wire cable to connect the input AC from a small PCB to the power supply. (Black-Line and White- Neutral). The chassis and power supply are grounded via the Protective Earth yellow/green wire. In some cases the L-N from our AC-PCB does not line up with L-N pins on the power supply, and we ask the manufacturer to reverse their connector. This is not a good approach as it leads to a 'custom' part and other documentation issues for the manufacture. If we were to go in for product safety testing, NRTL, with the L-N orientation reversed on what basis would be rejected. Would we? If a power supply is auto-ranging why would the orientation be important as L-L will appear on both pins in a 220VAC circuit. Most of these power supplies have fuses for both line and neutral. We also have a few power supplies that claim to be auto-ranging but have only one fuse, and I am not sure if these would 'qualify' for a L-N reverse. The other option we have is to provide manufacturing with two sets of cables, but that also can lead to other complications, such as BOMs which are power-supply-model-specific. Your experience and wisdom is greatly appreciated. Ryan Jazz Jayasinghe Compliance Engineer x1198 Canoga Perkins Direct:(818) 678-3898 20600 Prairie Street Company:(818) 718-6300 Chatsworth, CA 91311-6008 e-mail: [email protected] www.canoga.com FAX:(818) 678-3798 - ---------------------------------------------------------------- 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 <[email protected]> All emc-pstc postings are archived and searchable on the web at http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher <[email protected]> David Heald <[email protected]>
