My point is there is something broken in the approval system if someone can arbitrarily exclude something like a zero or peak-crossing switch.
Ken Javor Phone: (256) 650-5261 From: "[email protected]" <[email protected]> Date: Tue, 18 Oct 2022 10:46:01 -0600 To: Ken Javor <[email protected]> Cc: <[email protected]> Subject: Re: [PSES] Assess risk of electric shock from charged capacitors As I mentioned, I agree. However, I am not the one who signs the certification, so I must use the guidance I receive. -Doug Douglas E Powell Laporte, Colorado USA [email protected] LinkedIn <https://www.linkedin.com/in/coloradocomplianceguy/> (UTC -06:00) Mountain Time (US-MDT) On Tue, Oct 18, 2022 at 10:18 AM Ken Javor <[email protected]> wrote: > 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] <http://[email protected]> " <[email protected] > <http://[email protected]> > > Date: Tue, 18 Oct 2022 10:06:20 -0600 > To: Ken Javor <[email protected] > <http://[email protected]> > > Cc: <[email protected] <http://[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] <http://[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] > <http://[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]> >> <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 17:37:21 -0600 >> To: <[email protected] <http://[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]> <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]> <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]> <http://[email protected]> " <[email protected] >>> <http://[email protected]> <http://[email protected]> >>> <http://[email protected]> > >>> Reply-To: "[email protected] <http://[email protected]> >>> <http://[email protected]> <http://[email protected]> " <[email protected] >>> <http://[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]> <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]> >>> <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]> <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]> <http://[email protected]> > >>>> Sent: Monday, October 17, 2022 8:18 AM >>>> To: [email protected] <http://[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]>> <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]>> <http://[email protected]>> ; >>>> >>>> For policy questions, send mail to: >>>> Jim Bacher <[email protected]> <http://[email protected]>> >>>> <http://[email protected]>> <http://[email protected]>> ; >>>> David Heald <[email protected]> <http://[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]> >>> <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]> <http://[email protected]> > >>> >>> For policy questions, send mail to: >>> Jim Bacher <[email protected] <http://[email protected]> >>> <http://[email protected]> <http://[email protected]> > >>> David Heald <[email protected] <http://[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]> <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]> > > 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
