This is going downhill fast but I¹m enjoying the ride! Ken Javor Phone: (256) 650-5261
From: John Woodgate <[email protected]> Reply-To: John Woodgate <[email protected]> Date: Tue, 19 Jun 2018 22:29:44 +0100 To: <[email protected]> Subject: Re: [PSES] ESD question I think the model should assume a spherical body of the relevant mass, which capacitance in the archaic unit 'centimetres' is equal to its radius in cm, and 1 cm = 1.13 pF. With all respect to Doug, I think the BCI is about as scientific as BMI, which is at least a pressure (kg/metre-squared) of some sort. I'm not sure what pF/ns would represent. Of course the capacitance of a spherical grandmother of any radius is 1 nanafarad. John Woodgate OOO-Own Opinions Only J M Woodgate and Associates www.woodjohn.uk <http://www.woodjohn.uk> Rayleigh, Essex UK On 2018-06-19 22:06, Doug Smith wrote: > > Hi Ken and the group, > > The model started out in IEC 801-2 which had a 150 Ohm, 150 pF model. This > eventually became IEC 6000-4-2 at 330 Ohms and 150 pF. Both were meant to > model a piece of metal in a human hand. Such a discharge is an order of > magnitude more severe, even for a tiny piece of metal in one's hand, than a > discharge directly from a human hand if one measures the radiated EMI from > these events. > > The R and C above were the result of many measurements on people. The first > engineers to describe the IEC 61000-4-2 pulse as it is today, with the sharp > peak at the start, was Michael King and David Reynolds back when dinosaurs > roamed the earth in the last century. > > There is a semiconductor device handling spec called "Human Body Model" using > 100 pF and 1500 Ohms. But, for me, there are no good HBM simulators on the > market as they all have metallic tips. They need a tip composed of material > that has the same volume and surface resistivity as a human finger. There it > goes, now no one can patent the idea...it is now in the public domain. > > Since capacitance goes by surface area, we may need a new capacitance value > as the population has gained weight. I propose we replace BMI (Body Mass > Index) with the BCI (Body Capacitance Index) a combination of body free space > capacitance in pF of a person and the number of nanoseconds (at one foot per > nanosecond) it takes for light to go from head to foot. Like BCI = [body > capacitance]/[body length in nanoseconds at the speed of light]. For me that > might be about 25 pF/ns. Some of my friends might be about 45 pF/ns. > > Wow, two ideas in the same email! > > Doug > > > > On Tue, 19 Jun 2018 15:34:57 -0500, Ken Javor wrote: > > > What with Doug Smith being active in this sort of standard writing activity, > I doubt it¹s simply inertia. > > Ken Javor > Phone: (256) 650-5261 > > > > > From: John Woodgate <[email protected]> <mailto:[email protected]> > Date: Tue, 19 Jun 2018 21:26:38 +0100 > To: Ken Javor <[email protected]> > <mailto:[email protected]> , <[email protected]> > <mailto:[email protected]> > Subject: Re: [PSES] ESD question > > > > Probably handed down on a stone tablet in 1910 and no-one had the courage to > challenge it yet. (;-) > > > John Woodgate OOO-Own Opinions Only > J M Woodgate and Associates www.woodjohn.uk <http://www.woodjohn.uk> > <http://www.woodjohn.uk> > Rayleigh, Essex UK > > On 2018-06-19 21:18, Ken Javor wrote: > > >> ESD question Anyone out there know the origins of the 150 pF/330 ohm gun >> model used in EN61000-4-2 and derivative standards? It seems it ought to be a >> human body model, but it isn't. >> >> Ken Javor >> Phone: (256) 650-5261 - >> ---------------------------------------------------------------- >> >> >> 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]> <mailto:[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]> <mailto:[email protected]> >> Mike Cantwell <[email protected]> <mailto:[email protected]> >> >> >> For policy questions, send mail to: >> Jim Bacher <[email protected]> <mailto:[email protected]> >> David Heald <[email protected]> <mailto:[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) <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]>
