Mr P - Correct about the change of scoped voltage. UL62109-1 scopes 1500Vdc (not listed by ANSI or SCC yet), and NEC article 690 will be also updated.
FWIW, took customer's box back to the ranch and did several fault conditions and some surge stuff(C62.41 and 4-5). What a mess. They never listen. What a maroon. Brian -----Original Message----- From: Pete Perkins [mailto:00000061f3f32d0c-dmarc-requ...@ieee.org] Sent: Monday, January 26, 2015 7:28 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] FW: [PSES] OSM decision Rich, et al, I wouldn't be so quick to claim that dc systems will not have transient voltages on them. I recently worked on a certification project that included solar panels feeding power back into the line to make the overall project 'greener'. In commercial systems solar panels are ganged together to get the overall voltage up to 600Vdc with 10's of Amps per ganged collexion. 10 or more of these are combined to drive a SMPS inverter which outputs AC fed into the power system. Atmospherics can disrupt either the dc or the AC side so protection of the SMPS inverter on each side should be considered. More nightmares for the designers and field folks who need a clean design that is robust and long-lived giving continued protection. Some new work is being done with SPDs. See IEEE Xactions on EMC v56n6 Dec 2014: HE & Dy, SPD Protection Distance to Household Appliances Connected in Parallel. There might be other info that could be pulled from the bibliography for this paper. Finally, for your fun and enjoyment, the US NEC is being updated to allow the Low Voltage DC limits to go to 1000V soon and 1500Vdc later to accommodate larger solar panel installations. :>) br, Pete Peter E Perkins, PE Principal Product Safety Engineer PO Box 23427 Tigard, ORe 97281-3427 503/452-1201 fone/fax p.perk...@ieee.org -----Original Message----- From: Richard Nute [mailto:ri...@ieee.org] Sent: Monday, January 26, 2015 1:52 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] OSM decision What is the purpose of the MOV in this situation? What is the MOV Joule dissipation rating (can it dissipate the expected overvoltage)? Is the MOV protected by a fuse? (An equipment d.c. bus is not likely to have high-voltage transients.) -----Original Message----- From: Brian Oconnell [mailto:oconne...@tamuracorp.com] Sent: Monday, January 26, 2015 11:56 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] OSM decision Was reviewing customer's construction where a 475V MOV was across the (floated) 420Vdc bus. Said this was bad idea, and they referred me to OSM/EE decision sheet 09/01 for EN60950-1:2006; which says ok to do whatever you want with a VDR on primary side that is not connected to mains. Can think of more than one SFC that would result in this combination of circuit configuration and component ratings making a mess. Any record of TC108 having affirmed this? Thanks, Brian - ---------------------------------------------------------------- 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>
