Hi Christine,
IEC/UL/EN 60950-1 refers to LPS as a Limited Power Source, and is described in clause 2.5 of that standard. It encompasses a limitation on voltage, but also includes limiting of current and power as well. There are requirements in the standard that no longer need to be applied when a circuit is known to be LPS, that would need to be applied to a circuit that has limited voltage, but is not LPS. So, in general, you cannot simply replace a power supply with an LPS output with one with a non-LPS output and automatically have confidence that you are still compliant. Whether the non-LPS output supply would be acceptable in your end product/application will depend on the end product/application, and would need to be evaluated. Scott Aldous Compliance Engineer Advanced Energy Tel: 970-407-6872 Fax: 970-407-5872 ________________________________ From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Christine Rodham Sent: Wednesday, January 21, 2009 11:39 AM To: emc-p...@ieee.org Subject: Safety Experts: Limited Voltage Pwr Supplies vs. Non-Limited Voltage Power Supplies Hi List Members, We have a vendor that provides us a unit that uses an external power supply ( 90- 240VAC) The power supply is labeled LPS after the model number which means: Limited Voltage Power Supply. They recently changed vendors to another power supply with the EXACT same rating Except it was not marked as a LIMITED voltage power supply. Our supplier says this is not a compliance / safety issue because both supplies are recognized by UL and have the same voltage and current rating. So the $64,0000 dollar question is can you use a non- LPS in place of a LPS if they have the same rating? Thanks in advance, Thank you in advance! Christine Rodham - 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.ieeecommunities.org/emc-pstc 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 <emcp...@ptcnh.net> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher <j.bac...@ieee.org> David Heald <dhe...@gmail.com> This message, including any attachments, may contain information that is confidential and proprietary information of Advanced Energy Industries, Inc. The dissemination, distribution, use or copying of this message or any of its attachments is strictly prohibited without the express written consent of Advanced Energy Industries, Inc. - 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.ieeecommunities.org/emc-pstc 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 <emcp...@ptcnh.net> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher <j.bac...@ieee.org> David Heald <dhe...@gmail.com>
