The use of a Y1-rated cap across the pri/sec boundary in I.T. equip is not unusual for class 1 construction, but not necessarily ok for a class 2 power source, unless it has been tested for LPS and LCC requirements with the cap shorted.
I have discouraged this construction for ME, so I have no experience submitting this construction for approval in medical apparatus. In general, the 3d edition of IEC60601-1 allows the use of 60950-approved components only as a means of operator protection. And because the clause you are quoting is based on the 2d edition of IEC60601-1, a standard that is not clear on levels of protection and does not specify the (exact) means of protection, it seems that this construction would not be allowed. I would like to hear comments/corrections from other ME specialists. luck, Brian > -----Original Message----- > From: [email protected] [mailto:[email protected]]On Behalf Of Tarver, > Peter > Sent: Monday, April 16, 2007 11:47 AM > To: PSTC 1 > Subject: UL 60601-1, §56.4 > > > Good morning. > > A customer is intending to use a direct plug-in power supply > that is certified using the 60950-1 standards to supply a > medical device. The power supply is double insulated and > marked with IEC 60417, Symbol 5172. I am doing a gap > analysis on this power supply. > > This power supply has a capacitor (marked with sundry safety > agency logos and with, "X1 Y1," [which will be assumed true > for the purposes of this question]) that bridges primary and > secondary circuits. > > Do (or can) Y1 capacitors in such applications comply with > §56.4, first dashed paragraph? UL 60601-1 does not overtly > give credit for IEC 60384-x capacitors. > > In Appendix A of UL 60601-1, the rationale for §56.4 states, > "Such capacitors cannot provide DOUBLE INSULATION or > REINFORCED INSULATION." > > > Regards, > > Peter L. Tarver, PE > [email protected] - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html 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] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________
