Our product is an energy meter with an internal flyback power supply that mounts in Level III enclosures i.e. switchboards.
The voltage connections are Neutral, P1, P2, P3. Neutral is required to be connected to the building Neutral. P1 drives the power supply and the P1 Sense voltage divider. The P1 protection circuit is a series 10 ohm fusible resistor and MOV to Neutral. There is a 250VAC rated X2 capacitor across the MOV. P2 and P3 connections are not relevant to this issue. UL 61010 Appendix I refers to some common MAINS supply systems. Not having an earth connection, the closest standard configuration is "Three-Phase Four Wire with earthed Neutral" The standard Neutral to Phase voltage ratings for this configuration are 66, 120, 127, 220, 230, 240 The limiting factor in the product is the X2 rated capacitor at 250VAC. I assume the "standard" voltage ratings allow for variation on the upper side: a 240VAC system is expected to go as high as 264VAC. Is the same thing true for the ratings of an X2 rated capacitor; is the 250VAC rating a nominal rating, where the part expected to support 250VAC+10% say? The voltage rating we quote relates to both the power supply and the measurement range. The question is * what voltage should we put on the nameplate * what voltage can we claim that we can measure to while conforming to the standard? My guess is we should 240VAC on the nameplate, and note in the manual that the meter registers voltages as high as 264VAC Any help, much appreciated! Regards Jon Keeble - ---------------------------------------------------------------- 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>
