A simple circuit can provide disconnect at the peak of the ac waveform. Ken Javor Phone: (256) 650-5261
From: "[email protected]" <[email protected]> Reply-To: "[email protected]" <[email protected]> Date: Mon, 17 Oct 2022 13:08:17 -0600 To: <[email protected]> Subject: Re: [PSES] Assess risk of electric shock from charged capacitors 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 [email protected] 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 <[email protected]> wrote: > > > Hi Scott: > > Many dual channel scopes (whether digital or analog) include an ³add² 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 <[email protected]> > Sent: Monday, October 17, 2022 8:18 AM > To: [email protected] > 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 > <[email protected]> > > 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 <[email protected]> > > For policy questions, send mail to: > Jim Bacher <[email protected]> > David Heald <[email protected]> > > > 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 <[email protected]> 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 <[email protected]> For policy questions, send mail to: Jim Bacher <[email protected]> David Heald <[email protected]> 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 <[email protected]> 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 <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]> _________________________________________________ To unsubscribe from the EMC-PSTC list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1
