Rich & Pete. Thanks for your excellent explanation to this topic. Good lesson. Much appreciated. I can only speak for myself but I strongly believe that this topic/understanding needs to be brought more into the spotlight based on my previous discussions with some of my peers. Any of you care to do a whitepaper on this?
Regan On Wed, Feb 26, 2020 at 7:43 AM Pete Perkins <[email protected]> wrote: > Regan et al, > > > > The basic electric shock info for the levels selected in > the product standards come from IEC 60479 series, Effects of electric shock > on the human body… There are two sets of curves in IEC 60479-1 based upon > the data collected and evaluated (from the literature). One set of curves > is for AC and the other is for DC. These plot three body effects; > startle-reaction, letgo-immobilization and Ventricular Fibrillation as a > function of time. The names for these effects primarily come from the > effect of AC currents on the body. The DC effects are not as well defined > physiologically but are given the same names for consistency. The product > committees end up picking levels which seem appropriate for the application > and the values are not fully consistent between product standards, in spite > of the work of the IEC to make it so. > > A major difficulty is that the body effects are from the > current while the product committees would like to specify voltage, which > is easier to measure and verify compliance. > > The IEC long ago issued a simple 1201 Voltage Limits standard, aka 61201, > which was updated using a more complete evaluation and had a myriad of > curves for the various conditions based upon the choice of contact > parameters selected. This is so much more complicated than just selecting > a fixed voltage for most conditions and is not generally used in product > standards. > > So, in short, whether one picks 60Vdc or 70Vdc is not very > relevant in the overall human body effect picture; nor is a change of 4Vdc > around any of these values. > > Finally, as Rich stated, the DC value is not related to the > AC value by the sqrt 2. This works well for moving from AC to equivalent > DC voltage for hi-pot testing purposes but provides no path to the human > body effect which is different, as has been discussed here. > > > > :>) br, Pete > > > > Peter E Perkins, PE > > Principal Product Safety & Regulatory Affairs Consultant > > PO Box 1067 > > Albany, ORe 97321-0413 > > > > 503/452-1201 > > > > IEEE Life Fellow > > IEEE PSES 2020 Distinguished Lecturer > > [email protected] > > > > *From:* Regan Arndt <[email protected]> > *Sent:* Tuesday, February 25, 2020 8:49 PM > *To:* [email protected] > *Subject:* Re: [PSES] IEC 61010-1:2010 hazardous DC voltage > > > > Hi Rich. > > Thanks for your feedback. > > > > Correction/clarification. I was not trying to ‘convert’ to DC using 1.414 > (root 2). > > I merely used that ‘multiplication factor’ (1.414 & sometimes just 1.4) > based on the widely used/misused?/abused? that is used in the industry when > determining ‘equivalent’ DC values, just like one commonly does when > calculating the hipot test values. > > > > See: > https://electrical-engineering-portal.com/what-is-hipot-testing-dielectric-strength-test > <https://urldefense.proofpoint.com/v2/url?u=https-3A__electrical-2Dengineering-2Dportal.com_what-2Dis-2Dhipot-2Dtesting-2Ddielectric-2Dstrength-2Dtest&d=DwMFaQ&c=q6k2DsTcEGCcCb_WtVSz6hhIl8hvYssy7sH8ZwfbbKU&r=9-kTQUJB47k5_bHz_YekCwOWfoQDGgqgofVdnvpCXhM&m=X4OfXcJKn2LCMhQAhagkIEb6yDHp7Th9Mn0aSM9F6M4&s=57RvY_cM21TMTgAGuiIGMnZD0a7EcjWCvdfn0geu-kw&e=>, > where Jignesh Parmar quotes in his article: “Therefore, if we use dc test > voltage, we ensure that the dc *test voltage is under root 2 (or 1.414) > times the ac test voltage, so the value of the dc voltage is equal to the > ac voltage peaks.”* > > > > Another classic example comes from the 60950 standard for hipot values. > 1500 VAC/2121 DC (calculation factor = 1.414) > > > > That being said, I look forward to hear a response from someone on TC66 on > why they chose 70V. > > > > It would also be great if you could do a whitepaper (& speak) on the > understanding of how the body reacts to AC & DC for this year’s PSES > symposium in Chicago? 😉 > > > > Regan > > > > On Tue, Feb 25, 2020 at 4:07 PM Richard Nute <[email protected]> wrote: > > > > > > Hi Regan: > > > > The “bump” occurred from 1st edition, 1990, to 2nd edition, 2001. The 2nd, > 2001, and 3rd, 2010, are the same. > > > > Be careful with your math and DC interpretation. The rms voltage limit is > 33. The ac peak is 1.414 x 33 = 46.7. The DC is 70, which is unrelated to > the AC voltages (which is because of how the body reacts to AC and DC). > > > > As to the rationale for the change from 1st to 2nd, I suggest you find a > member of TC66 and ask for the documents preceding the 2nd. > > > > Touch voltages are specified in IEC TS 61201. In this standard both 30 > and 33 volts rms are listed, with very little difference in body reaction. > Same for 60 versus 70 volts DC. > > > > Best regards, > > Rich > > > > > > > > *From:* Regan Arndt <[email protected]> > *Sent:* Tuesday, February 25, 2020 2:38 PM > *To:* [email protected] > *Subject:* [PSES] IEC 61010-1:2010 hazardous DC voltage > > > > Dear fellow members, > > > > I am trying to understand the 'rationale/history' of why TC66 bumped up > the DC voltage by a mere 4 volts for hazardous voltages. > > As we know by simple math, 46.7 Vp x 1.414 = 66 VDC.............where, why > and how did the extra 4 volts come about? > > I need a history lesson here.... ;) > > > > Also, will these voltages also come back to normal in Ed 4? (i.e. 42.4 Vp, > 60 VDC) > > > > Thanks for shedding any light on this? > > > > Regan Arndt > > > > > > - > ---------------------------------------------------------------- > > 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 > > Attachments are not permitted but the IEEE PSES Online Communities site at > http://product-compliance.oc.ieee.org/ can be used for graphics (in > well-used formats), large files, etc. > > 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: > Scott Douglas <[email protected]> > Mike Cantwell <[email protected]> > > For policy questions, send mail to: > Jim Bacher <[email protected]> > David Heald <[email protected]> > > - > ---------------------------------------------------------------- > > 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 > > Attachments are not permitted but the IEEE PSES Online Communities site at > http://product-compliance.oc.ieee.org/ can be used for graphics (in > well-used formats), large files, etc. > > 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: > Scott Douglas <[email protected]> > Mike Cantwell <[email protected]> > > For policy questions, send mail to: > Jim Bacher <[email protected]> > David Heald <[email protected]> > - ---------------------------------------------------------------- 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 Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. 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: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
