The comparison is inaccurate and misleading. A measuring device must be suitable to the application, so recognized and calibrated and approved for use. A device that is a stimulus, or a means to a stimulus, whose proper operation is measured and verified by an accepted and calibrated device should not even be a subject of debate.
Ken Javor Phone: (256) 650-5261 From: "[email protected]" <[email protected]> Date: Tue, 18 Oct 2022 10:06:20 -0600 To: Ken Javor <[email protected]> Cc: <[email protected]> Subject: Re: [PSES] Assess risk of electric shock from charged capacitors Ken, I may be wrong but I believe the reluctance to accept in-house constructed circuits is similar to the low acceptance of digital meters for touch current measurements that we saw until the 1980s. Until True R.M.S. DVMs had a well established track record (e.g. Fluke 8060A), neither my LGA or CSA certification engineers would accept those, and I kept a calibrated analog meter on hand for a very long time. A similar concern was expressed for capacitor discharge testing, any in-house trigger circuit that is not able to carry a calibration label was suspect. I agree that a small circuit can be validated and used, although I've personally not heard directly from any agency representative that this is now possible. -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 8:12 PM Ken Javor <[email protected]> wrote: > 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] <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 17:37:21 -0600 > To: <[email protected] <http://[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] <http://[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] > <http://[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]> >> <http://[email protected]> " <[email protected] <http://[email protected]> >> <http://[email protected]> > >> Reply-To: "[email protected] <http://[email protected]> >> <http://[email protected]> " <[email protected] <http://[email protected]> >> <http://[email protected]> > >> Date: Mon, 17 Oct 2022 13:08:17 -0600 >> To: <[email protected] <http://[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]> <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]> <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]> >>> <http://[email protected]> > >>> Sent: Monday, October 17, 2022 8:18 AM >>> To: [email protected] <http://[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]>> >>> <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]>> >>> <http://[email protected]>> ; >>> >>> For policy questions, send mail to: >>> Jim Bacher <[email protected]> <http://[email protected]>> >>> <http://[email protected]>> ; >>> David Heald <[email protected]> <http://[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]> <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]> >> <http://[email protected]> > >> >> For policy questions, send mail to: >> Jim Bacher <[email protected] <http://[email protected]> >> <http://[email protected]> > >> David Heald <[email protected] <http://[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. 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]> > > 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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