Dear Rich, Thank you. DC input comes from solar cells therefore from outside. UL 1741 states that OVC IV needs to be used and for 120/240V it means 4000V. So what transient should I use from DC side?
Why table 8.1 in UL840 also mentions dc input? Best regards, Bostjan Boštjan Glavič Vodja laboratorija, Laboratorij za elektroniko Head of Laboratory, Laboratory of Electronic Engineering [SIQlogo60px] www.siq.si<http://www.siq.si/> SIQ Ljubljana, Trzaska c. 2, SI-1000 Ljubljana, Slovenia, VAT ID: SI23509678 t +386 (0)1 4778 265<tel:+386%20(0)1%204778%20265>, m +386 (0)41 391 283<tel:+386%20(0)41%20391%20283>, f +386 (0)1 4778 444<tel:+386%20(0)1%204778%20444> On 6. avg. 2014, at 20:17, "Richard Nute" <[email protected]<mailto:[email protected]>> wrote: Dear Boštjan: Despite UL1741 and UL 840, OVC does not apply to DC. There is no research that I know of that supports use of AC OVC to DC. If the 450 V DC is not outside the building or is otherwise not subject to lightning-caused overvoltages, OVC does not apply. Likewise, if the 450 V DC only supplies a limited number of other loads (which are assumed to generate transients when switched on or off), OVC does not apply. Since there is no isolation from input to output, whatever insulation between input and output is "functional" insulation. The transients that appear on the AC output side (generated by load switching and lightning) will also appear on the DC side. 120\240 V overvoltages are OVC II and are 3 kV according to IEC 60664, not 4 kV. Best regards, Rich On 8/6/2014 10:39 AM, Boštjan Glavič wrote: Dear experts, I am trying to figure out how to determine correct spacings for non-isolated inverter. According UL1741 OVC IV needs to be considered for inverter. From table 8.1 from UL840 I get a transients of 8,0kV for 450VDC input. Is that correct? Output of inverter is connected to AC grid 120/240V. This results in 4kV transients. We have no insulation input/output. Which transient level should I then use? 8kV transient on AC output side is almost impossible for the design. Any idea? Best regards, Bostjan Glavic SIQ - ---------------------------------------------------------------- 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]<mailto:[email protected]>> 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)<http://www.ieee-pses.org/list.html> List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]<mailto:[email protected]>> Mike Cantwell <[email protected]<mailto:[email protected]>> For policy questions, send mail to: Jim Bacher <[email protected]<mailto:[email protected]>> David Heald <[email protected]<mailto:[email protected]>> - ---------------------------------------------------------------- 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://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 <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
