Brian - >From what I can glean from your message, the equipment is Class 1, but the secondaries do not rely on earthing for SELV reliability (hence, the Reinforced Insulation EST value). However, there appears to be some functional earthing of secondary circuits or there would be no problems for your Y caps.
If the above is true, the Y caps must provide Reinforced insulation. Alternatively, there are allowances for two Y caps in series you might be able to exploit (see 1.5.7.1). If the above is not true, in that earthing of secondary circuits is necessary to maintain compliance with SELV requirements, you should not need to perform an EST at Reinforced values. Basic Insulation will do, eliminating issue for the Y caps. Irrespective of these alternatives, the implication of only needing Basic Insulation for the Y cap and Reinforced Insulation for the purposes of your primary to secondary EST is that you should be able to completely disconnect the Y cap and leave it dangling, without connecting the Y cap at all. Challenge the test house engineer for a solid engineering rationale. Regards, Peter L. Tarver, PE Product Safety Manager Sanmina-SCI Homologation Services San Jose, CA peter.tar...@sanmina-sci.com > -----Original Message----- > From: owner-emc-p...@majordomo.ieee.org > [mailto:owner-emc-p...@majordomo.ieee.org]On > Behalf Of Brian O'Connell > Sent: Thursday, August 22, 2002 6:57 AM > To: emc-p...@majordomo.ieee.org > Subject: electric strength test > > > > Good People of PSTC: > > I am attempting to comply with both the letter > and spirit of 60950:2000, cl > 5.2. Note that 5.2.2 allows for separate testing, > according the type of > insulation required. When testing a (class 1) > power supply, the withstand > level for primary to chassis is Basic; and for > primary to secondary is > Reinforced. Typically, I will apply approx > 2500vdc for Basic and 4300vdc for > reinforced. But to pass primary to secondary > test, 60950 says that I can > allow for following: > > "care is taken that the voltage applied to the > reinforced insulation does > not overstress basic...". > > Also > > "to avoid damage to components or insulation > which are not involved in the > test, disconnection of ICs or the like and the > use of equipotential bonding > are permitted." > > For Pri/Sec testing, the screw connecting the > Y-caps to the chassis is > removed, insulation is inserted between the screw > insert and chassis. > > A (new) agency engineer says that inserting a > piece of insulator defeats the > purpose of the test. For class 1 construction, it > is just not possible for > me to pass 4300vdc test levels without inserting > my little piece of valox, > unless I physically remove all Y-caps (and the > unit will not operate > reliably with y-caps). I have inspected units > from several other companies > and have determined that it was not possible to > have ever passed pri-sec > test levels without isolating these circuits. > > What test technique generally accepted by your > agency engineers? TIA. > > R/S, > Brian O'Connell > Taiyo Yuden (USA), Inc. > > > ------------------------------------------- > 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" ------------------------------------------- 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"
