bmail rev 3.13 smptlib 2.7.10 UL508 points to UL840 as alternate for spacing at terminals and internal crp/clr. UL508 wants you to be min OV cat III for use of UL840. Also UL840 addresses 'recurring peak voltages' for PCB spacings.
Brian From: McDiarmid, Ralph [mailto:[email protected]] Sent: Wednesday, September 09, 2015 10:20 AM To: [email protected] Subject: Re: [PSES] requirement for spacings Clause 5.2.3 in EN50178 (Decisive Voltage) should help clarify. It writes about "occurs continuously" and "worst operating condition". I don't think UL508 will be much help, unless it allows use of UL840 (insulation coordination) as an alternate approach to spacings. _______________________________________________________________________________ Ralph McDiarmid | Schneider Electric | Solar Business | CANADA | Regulatory Compliance Engineering From: Boštjan Glavič <[email protected]> To: [email protected], Date: 09/09/2015 09:47 AM Subject: Re: [PSES] requirement for spacings ________________________________________ Dear Scot, Douglas, Thank you. Unit is investigated to UL 508, IEC 62477-1 and EN 50178. I have experiences with IEC 60950-1 which requires to determine required distances based on rated voltage - tolerances not considered. 840 VDC might appear on the input during start up of the generator. However I need to agree with you that 30% tolerances seem to be very high and not consider that might be wrong. Best regards, Bostjan On 9. sep. 2015, at 17.41, Douglas Powell <[email protected]<mailto:[email protected]>> wrote: Bostjan, As Scott mentioned, it is very important to know which end standard is being applied to this product. In addition there are many other factors such as environmental conditions, application, location, etc. If this is truly DC powered, it is entirely possible your spacings will be for secondary circuits and somewhat reduced. Nevertheless wiring, connections, fuses and the like will have to be rated and certified/listed for that voltage. If you can provide a little more information about the application and end use, we may be able to provide better assistance. All the best, Doug From: Scott Aldous Sent: Wednesday, September 9, 2015 9:15 AM To: [email protected]<mailto:[email protected]> Reply To: Scott Aldous Subject: Re: [PSES] requirement for spacings Hi Bostjan, It's difficult to give detailed guidance without knowing what end standards are being applied, but the general guidance in IEC 60664-1 should be helpful. In general, +30% tolerance on input voltage is outside the assumptions of most (if not all) safety standards. An electrical rating of 560Vdc +30%/-15% doesn't seem to be appropriate and should be expressed as a range instead. The range here is from 476 - 728 Vdc! For example, 600V rated wire would seem to be an acceptable choice for external wiring for the input of a device marked with a 560V input rating, but in this case the input voltage may be able to be significantly higher than 600V for extended periods. A marked rating of 560Vdc would be misleading. If your end standard allows the clearances to be determined based on assumed transient levels, then the nominal input voltage (or voltages) becomes less important for clearances as long as you are able to make an accurate assumption about the transients. The 840Vdc level potentially could be taken as a temporary overvoltage for the purposes of calculation of clearance, again depending on the end product standard. At least one end product standard that I know of, IEC 62109-1, takes both transient overvoltages and temporary overvoltages into account for calculation of clearances. For creepage, at a minimum, I think you would want to base creepage distance requirements on the 728Vdc high end of the input voltage (560Vdc + 30%). Whether or not you should use the 840Vdc level instead may depend on the specifics of the case, such as how frequently this can happen, what controls are in place to ensure that this is reliably the case, etc. Again, the requirements of the end product standard need to be taken into account and will certainly influence your decision. On Wed, Sep 9, 2015 at 4:03 AM, Boštjan Glavič <[email protected]<mailto:[email protected]>> wrote: Dear Experts, Manufacturer specified rated voltage of his product as 560VDC +30%/-15% but input voltage can temporarily reach 840VDC (max 1 min). Do we need to consider 840VDC for determination of required distances? Usually standard requires to consider rated voltage only what is in this case 560VDC (marked on the label). Thank you for your support. Best regards, Bostjan Boštjan Glavič Laboratory of Electronic Engineering Head of Laboratory SIQ Ljubljana, Tržaška cesta 2 SI-1000 Ljubljana, Slovenia T: + 386 (0)1 47 78 265<tel:%2B%20386%20%280%291%2047%2078%20265> F: + 386 (0)1 47 78 444<tel:%2B%20386%20%280%291%2047%2078%20444> E-Mail: [email protected]<mailto:[email protected]> - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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