Hi Mr. Ron Pickard: According to IEC60950:1999,Go to 1.5.7 accessible parts of the equipment having bridging capacitor are subject to the limited current test of 2.4. If it is ok for 2.4 (<0.7mA peak), not ok for 0.25mA(>0.25mA and <0.7mA)
EUT is Class II equipment, output pins are qualified as accessible parts not connected to the earth IEC60950 imply different requiremnts for accessible parts(sub1.5.7,sub. 2.4, sub. 5.2) Whether we can judge the equipment is OK for IEC60950 my opinion is OK any comments are appreciated Xing weibing 2002-06-26 ----- Original Message ----- From: "Ron Pickard" <[email protected]> To: <[email protected]> Cc: <[email protected]> Sent: Tuesday, June 25, 2002 11:50 PM Subject: Re: TOUCH CURRENT LIMIT > > > Hi Xing, > > Find my comments below marked with ***. > > Your email stated: > >Our test lab receive a CB TEST REPORT FOR NATIONAL RECOGNIZATION, > >the EUT is a class II ac adapter having a bridging capacitor (4700pF)across > >the reinforced > insulation > >The touch current measured by CB is 0.17mA(4700pF declared) > >but the value we measure is 0.28mA(4700pF) > >which one is correct ? > > *** To answer your question, you/we will need to know the applied voltage and > frequency across that > capacitor. On the surface, it does appear that the CB and your lab measured > this parameter under > different conditions. Also, was this single capacitor the only component that > was bridging the > reinforced barrier during the CB's test? > > >it depend on test equipment? > > *** Possibly. > > >How to judge > > *** This can easily be calculated. The measured results should be very close > to the calculated > results. For instance: > @120V 60Hz, I = 0.213 mA > @220V 50Hz, I = 0.325 mA > @240V 50Hz, I = 0.354 mA > @264V 50Hz, I = 0.390 mA > > >How to obtain accurate result? > > *** Use good quality instruments (I'm sure that you are) with suitable > measurement resolution. > > I hope this will assist you in approaching a satisfactory resolution to your > problem. > > Comments anyone? > > Best regards, > > Ron Pickard > [email protected] > > > > ------------------------------------------- > 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: > [email protected] > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Ron Pickard: [email protected] > Dave Heald: [email protected] > > For policy questions, send mail to: > Richard Nute: [email protected] > Jim Bacher: [email protected] > > 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: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] 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"
