I¹m curious as to the rationale behind that. It should be obvious that the power was turned off at the appropriate time. That would be demonstrated using an o¹scope, just as in the hit or miss method.
What¹s different? Ken Javor Phone: (256) 650-5261 From: "[email protected]" <[email protected]> Reply-To: "[email protected]" <[email protected]> Date: Mon, 17 Oct 2022 17:37:21 -0600 To: <[email protected]> Subject: Re: [PSES] Assess risk of electric shock from charged capacitors Ken, Yes, but I have had certification engineers hesitate or disallow using any home-brew solid state circuits to control safety testing. -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 1:18 PM Ken Javor <[email protected]> wrote: > A simple circuit can provide disconnect at the peak of the ac waveform. > > Ken Javor > Phone: (256) 650-5261 > > > > From: "[email protected] <http://[email protected]> " <[email protected] > <http://[email protected]> > > Reply-To: "[email protected] <http://[email protected]> " <[email protected] > <http://[email protected]> > > Date: Mon, 17 Oct 2022 13:08:17 -0600 > To: <[email protected] <http://[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] <http://[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] > <http://[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] <http://[email protected]> > >> Sent: Monday, October 17, 2022 8:18 AM >> To: [email protected] <http://[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]> <http://[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]> <http://[email protected]>> ; >> >> For policy questions, send mail to: >> Jim Bacher <[email protected]> <http://[email protected]>> ; >> David Heald <[email protected]> <http://[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] <http://[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] <http://[email protected]> > > > For policy questions, send mail to: > Jim Bacher <[email protected] <http://[email protected]> > > David Heald <[email protected] <http://[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. 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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. 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