Re: [PSES] Voltage Rating vs Voltage Specification

[Doug Powell]

Dave,  I like you motor example.  It's one more bit I can add to make my case.  I guess I'm resigned to always having to explain this.   best, doug From: dave.nyffeneg...@bhemail.com Sent: April 5, 2017 5:43 PM To: doug...@gmail.com; EMC-PSTC@LISTSERV.IEEE.ORG Subject: RE: [PSES] Voltage Rating vs Voltage Specification Ha!  Age old problem.  Just have to explain it as you did.  And also for the end product consumer nameplate I don’t put the +-10% rating on the plate.  Had a major motor manufacturer recently trying to tell me that the motor they have rated for 230V was OK to run at 208V because it’s good for 230 +-10%. Had to explain to them that I need it to run at 208V – 10%.  Crickets on that one. A previous motor from that manufacturer was rated for something like 208V @60Hz but 190V @50Hz and sure enough when tested at 208V + 10% @ 50Hz the windings saturated and drew crazy current.    Likewise have to explain to design engineers that they cannot use a 230V motor in the product rated at 208V and rate the end product at 208V – 0%.   -Dave   From: Doug Powell [mailto:doug...@gmail.com] Sent: Wednesday, April 05, 2017 6:52 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] Votlage Rating vs Voltage Specificaion   Hi all,   Has anyone found a good way to explain to non-compliance types the difference between voltage rating and voltage specification?  After all these years I still run into this discussion and have not found a good way to clear the air.   A classic example is an open frame AC/DC power supply used to produce the housekeeping voltages within a larger product.  In a recent example, the PSU datasheet stated the voltage input range as 85 to 264 VAC.  This is great and I really like that specification. However, I also had a design engineer who took those numbers from the datasheet and transcribed them directly to the rating label of his product.  As a result the agency engineer wanted to apply the ±10% rule to the rating label voltage and the rating tests were then 76.5 to 290.4 VAC (this was not an ITE product).  Note: a little quick math shows that the 264 VAC upper limit of the PSU is actually a result of 240 V plus 10%.    All this seems obvious to me but apparently not to everyone ... and maybe it's me who is just a few sandwiches short of a picnic.   I would be grateful to hear any experiences where explanations were successful and lasting.     --   Douglas E Powell doug...@gmail.com http://www.linkedin.com/in/dougp01 - ---------------------------------------------------------------- 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> - ---------------------------------------------------------------- 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>