On the question of probe resistance, I always recommend 100:1 probes which will have a negligible effect on overall timing. Additionally, it may be necessary to perform the test a number times to ensure the disconnect occurs at the peak of the sine wave. For me, experience has shown this may take up to 10x attempts.
-Doug Douglas E Powell Laporte, Colorado USA doug...@gmail.com LinkedIn <https://www.linkedin.com/in/coloradocomplianceguy/> (UTC -06:00) Mountain Time (US-MDT) On Mon, Oct 17, 2022 at 11:32 AM Richard Nute <ri...@ieee.org> wrote: > > > > > Hi Scott: > > > > Many dual channel scopes (whether digital or analog) include an “add” > function for the two channels. One channel must be inverted to measure the > charged capacitance. > > > > The resistance of the two probes must be accounted for in the capacitance > discharge time. (The same – for only one probe -- is true for the scheme > using an isolating transformer.) > > > > You should get the same results for both methods. > > > > Best regards, > > Rich > > IEEE Life Fellow > > IEEE Medal for Environmental and Safety Technologies > > > > > > > > *From:* Scott Xe <scott...@gmail.com> > *Sent:* Monday, October 17, 2022 8:18 AM > *To:* EMC-PSTC@LISTSERV.IEEE.ORG > *Subject:* Re: [PSES] Assess risk of electric shock from charged > capacitors > > > > In order to judge if there is no risk of electric shock from charged > capacitors, it is required to measure the voltage across L and N of mains > plug after the removal of power input. To avoid grounding loop between > test equipment and the unit under test, an isolating transformer is > strongly recommended. I have learnt another way by using Add Function and > two hot probes of a dual channel DSO. Can someone advise which way is more > common in safety conformity test. Especially the latter one, I have not > tried it yet before and appreciate any notes I must take in the measurement. > > > > Thanks and regards, > > > > Scott > - > ---------------------------------------------------------------- > > 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 > > Website: http://www.ieee-pses.org/ > Instructions: http://www.ieee-pses.org/list.html (including how to > unsubscribe) <http://www.ieee-pses.org/list.html> > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > Mike Cantwell <mcantw...@ieee.org> > > For policy questions, send mail to: > Jim Bacher <j.bac...@ieee.org> > David Heald <dhe...@gmail.com> > ------------------------------ > > To unsubscribe from the EMC-PSTC list, click the following link: > https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1 > - ---------------------------------------------------------------- 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 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: Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com> _________________________________________________ To unsubscribe from the EMC-PSTC list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1
