Joe - The 72Vdc issue was an attempt to explain the TNV-2 aspect, since that clearly exceeds SELV limits.
The "influences of polarity" is intended to address miswiring and tends to force some type of reverse polarity protection (diodes, connectorization or something more sophisticated). CO battery plant tolerances are generally not adequately addressed in IEC60950, but an attempt to address the issue is in the third dashed paragraph of Subclause NAB.2 of CSA/UL60950, 3rd ed. These values are largely derived from ANSI T1.315. Regards, Peter L. Tarver, PE Product Safety Manager Sanmina-SCI Homologation Services San Jose, CA peter.tar...@sanmina-sci.com > -----Original Message----- > From: Joe Finlayson > > Peter, > > I am aware of the float voltages and agree > that a 60VDC rating > **should be** tested up to 72VDC. However, I > still feel that DC tolerances > are not adequately reflected in the body of the > standard. Is the phrase > "influences of polarity" intended to reference > float voltages??? > > Thx, > > > Joe > > -----Original Message----- > From: Peter L. Tarver > > Joe - > > When the nominal CO supply voltage is 60Vdc and batteries > are charging, the "float voltage" is closer to > 72Vdc. Test > houses are aware of this and take it into account when > performing their evaluations. > > > Regards, > > Peter L. Tarver, PE > > > -----Original Message----- > > From: Joe Finlayson > > > > I see section 1.4.5 addressing the > > determination of the most > > unfavorable supply voltage for a test. The > > tolerance to be taken into > > account is clear for the determination of AC > > mains powered equipment. All > > it says for DC powered equipment is that the > > influence of polarity shall be > > taken into account. I see coming up with a > > potential of 60VDC either way. > > Was the intent here to state something I am missing? > > > > Thx, > > > > > > Joe ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
