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 doug...@gmail.com 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 <ken.ja...@emccompliance.com> 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: *"doug...@gmail.com" <doug...@gmail.com> > *Date: *Tue, 18 Oct 2022 10:06:20 -0600 > *To: *Ken Javor <ken.ja...@emccompliance.com> > *Cc: *<EMC-PSTC@listserv.ieee.org> > *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 > doug...@gmail.com > 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 <ken.ja...@emccompliance.com> > wrote: > > I’m 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 o’scope, just as in the hit or miss method. > > What’s different? > > Ken Javor > Phone: (256) 650-5261 > > > ------------------------------ > *From: *"doug...@gmail.com <http://doug...@gmail.com> " <doug...@gmail.com > <http://doug...@gmail.com> > > *Reply-To: *"doug...@gmail.com <http://doug...@gmail.com> " < > doug...@gmail.com <http://doug...@gmail.com> > > *Date: *Mon, 17 Oct 2022 17:37:21 -0600 > *To: *<EMC-PSTC@LISTSERV.IEEE.ORG <http://EMC-PSTC@LISTSERV.IEEE.ORG> > > *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 > doug...@gmail.com <http://doug...@gmail.com> > 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 <ken.ja...@emccompliance.com < > http://ken.ja...@emccompliance.com> > wrote: > > A simple circuit can provide disconnect at the peak of the ac waveform. > > Ken Javor > Phone: (256) 650-5261 > > > ------------------------------ > *From: *"doug...@gmail.com <http://doug...@gmail.com> < > http://doug...@gmail.com> " <doug...@gmail.com <http://doug...@gmail.com> > <http://doug...@gmail.com> > > *Reply-To: *"doug...@gmail.com <http://doug...@gmail.com> < > http://doug...@gmail.com> " <doug...@gmail.com <http://doug...@gmail.com> > <http://doug...@gmail.com> > > *Date: *Mon, 17 Oct 2022 13:08:17 -0600 > *To: *<EMC-PSTC@LISTSERV.IEEE.ORG <http://EMC-PSTC@LISTSERV.IEEE.ORG> < > http://EMC-PSTC@LISTSERV.IEEE.ORG> > > *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 > doug...@gmail.com <http://doug...@gmail.com> <http://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 < > http://ri...@ieee.org> <http://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 <http://scott...@gmail.com> < > http://scott...@gmail.com> > > *Sent:* Monday, October 17, 2022 8:18 AM > *To:* EMC-PSTC@LISTSERV.IEEE.ORG <http://EMC-PSTC@LISTSERV.IEEE.ORG> < > http://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> <http://emc-p...@ieee.org>> < > http://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> <http://mcantw...@ieee.org>> < > http://mcantw...@ieee.org>> ; > > For policy questions, send mail to: > Jim Bacher <j.bac...@ieee.org> <http://j.bac...@ieee.org>> < > http://j.bac...@ieee.org>> ; > David Heald <dhe...@gmail.com> <http://dhe...@gmail.com>> < > http://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. 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