Human Body Capacitance and Resistance
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From: Archimedes' Lever on 1 Jun 2010 03:14 On Mon, 31 May 2010 21:58:34 -0500, "Shaun" <rowl(a)nomail.com> wrote: > >"Archimedes' Lever" <OneBigLever(a)InfiniteSeries.Org> wrote in message >news:0cb606hljsk5dgsdkjm2rvbk0699ehq7j0(a)4ax.com... >> On Sun, 30 May 2010 19:57:54 -0500, "Shaun" <rowl(a)nomail.com> wrote: >> >>> because there is a direct connection to the internal fluids of the >>>body, >> >> >> That is what I said, dumbfuck. > >No it's not. You talked about all sorts of variations. > No, dumbfuck, I directly referenced the blood. You lose... again... as usual.
From: Dirk Bruere at NeoPax on 1 Jun 2010 06:31 On 01/06/2010 01:09, Winfield Hill wrote: > Dirk Bruere at NeoPax wrote... >> >> On 30/05/2010 12:49, Winfield Hill wrote: >>> A repost of a comment I made elsewhere, for discussion here. >>> >>> The subject is ESD Human Body model values. I'm enamored by >>> a 1989 symposium paper by Richard Fisher, of Sandia Nat'l Labs, >>> where he created a "Severe Human ESD Body Model." His model >>> had worst-case numbers meant for use in electrostatic-discharge >>> circuit-protection analysis, etc. >>> >>> Fisher's Severe Body Model consists of two parts, the body and an >>> arm with hand reaching out to zap something. The body part has >>> 400pF of capacitance in series with 250 ohms and 0.5uH. Then the >>> arm and hand part bridges the body terminals with 10pF, and finally >>> we have another 110 ohms and 0.1uH in series to complete the model >>> and connect it to the poor real-world victim. The body capacitance >>> is higher than you may see elsewhere first because the body is >>> sitting down, and second because it's a worst-case body. We won't >>> go further into what that means. :-) >>> >>> You charge the 400pF capacitor to a voltage of your choosing. >>> 20kV is a nice high number. During discharge we get a fast spike >>> of current from the 10pF, with sub-ns risetime to dangerous levels, >>> with up to 5A peak current, and lasting up to 5ns into the "load." >>> This is followed by a slower discharge of the 400pF capacitance, >>> lasting up to 200ns. >>> >>> This would be followed by, ahem, a postmortem. > >> Well, since people regularly charge themselves up to at least >> 30kV (a 1 cm spark) I would say not. > > Right you are. As I clarified earlier, I was thinking of a > component postmortem. Also, given the hypothesized rapid rise time, doesn't most of the current flow on the surface ie skin - a literal "skin effect"? -- Dirk http://www.transcendence.me.uk/ - Transcendence UK http://www.blogtalkradio.com/onetribe - Occult Talk Show
From: Dirk Bruere at NeoPax on 1 Jun 2010 06:33 On 01/06/2010 02:32, Mycelium wrote: > On Tue, 01 Jun 2010 00:18:18 +0100, Dirk Bruere at NeoPax > <dirk.bruere(a)gmail.com> wrote: > >> On 30/05/2010 12:49, Winfield Hill wrote: >>> A repost of a comment I made elsewhere, for discussion here. >>> >>> The subject is ESD Human Body model values. I'm enamored by >>> a 1989 symposium paper by Richard Fisher, of Sandia Nat'l Labs, >>> where he created a "Severe Human ESD Body Model." His model >>> had worst-case numbers meant for use in electrostatic-discharge >>> circuit-protection analysis, etc. >>> >>> Fisher's Severe Body Model consists of two parts, the body and an >>> arm with hand reaching out to zap something. The body part has >>> 400pF of capacitance in series with 250 ohms and 0.5uH. Then the >>> arm and hand part bridges the body terminals with 10pF, and finally >>> we have another 110 ohms and 0.1uH in series to complete the model >>> and connect it to the poor real-world victim. The body capacitance >>> is higher than you may see elsewhere first because the body is >>> sitting down, and second because it's a worst-case body. We won't >>> go further into what that means. :-) >>> >>> You charge the 400pF capacitor to a voltage of your choosing. >>> 20kV is a nice high number. During discharge we get a fast spike >>> of current from the 10pF, with sub-ns risetime to dangerous levels, >>> with up to 5A peak current, and lasting up to 5ns into the "load." >>> This is followed by a slower discharge of the 400pF capacitance, >>> lasting up to 200ns. >>> >>> This would be followed by, ahem, a postmortem. >> >> Well, since people regularly charge themselves up to at least 30kV (a 1 >> cm spark) I would say not. > > > Except that he was referring to the chip. D'oh! OK - I get it now! I did that once with an expensive chip. A guy passed it to me and, unthinking, as I went to take it there was a big fat spark that leapt through its pins. Straight to the rubbish bin. -- Dirk http://www.transcendence.me.uk/ - Transcendence UK http://www.blogtalkradio.com/onetribe - Occult Talk Show
From: Dirk Bruere at NeoPax on 1 Jun 2010 06:35 On 01/06/2010 03:00, Don Klipstein wrote: > In article<86iudiFmtmU4(a)mid.individual.net>, Dirk Bruere at NeoPax wrote: >> On 30/05/2010 12:49, Winfield Hill wrote: >>> A repost of a comment I made elsewhere, for discussion here. >>> >>> The subject is ESD Human Body model values. I'm enamored by >>> a 1989 symposium paper by Richard Fisher, of Sandia Nat'l Labs, >>> where he created a "Severe Human ESD Body Model." His model >>> had worst-case numbers meant for use in electrostatic-discharge >>> circuit-protection analysis, etc. >>> >>> Fisher's Severe Body Model consists of two parts, the body and an >>> arm with hand reaching out to zap something. The body part has >>> 400pF of capacitance in series with 250 ohms and 0.5uH. Then the >>> arm and hand part bridges the body terminals with 10pF, and finally >>> we have another 110 ohms and 0.1uH in series to complete the model >>> and connect it to the poor real-world victim. The body capacitance >>> is higher than you may see elsewhere first because the body is >>> sitting down, and second because it's a worst-case body. We won't >>> go further into what that means. :-) >>> >>> You charge the 400pF capacitor to a voltage of your choosing. >>> 20kV is a nice high number. During discharge we get a fast spike >>> of current from the 10pF, with sub-ns risetime to dangerous levels, >>> with up to 5A peak current, and lasting up to 5ns into the "load." >>> This is followed by a slower discharge of the 400pF capacitance, >>> lasting up to 200ns. >>> >>> This would be followed by, ahem, a postmortem. >> >> Well, since people regularly charge themselves up to at least 30kV (a 1 >> cm spark) I would say not. > > 30 KV per centimeter is the breakdown gradient of air. But that number > only correlates to spark gap length when the eectric field is even just > before breakdown. > > In the usual case of people charging themselves up by shuffling their > shoes on carpet, they make sparks in gaps with uneven electric field. So, > less than 30 KV can make a 1 cm spark. If one end of the spark gap is a > sharp point or the tip of a wire maybe AWG 22 (approx. .63 mm) or smaller, > then a 1 cm spark can occur from about 11 KV, easily from 12KV. > > Also, these sparks often appear bigger than they are. I find 1 cm to be > uncommon, but I find 8 mm fairly easy to achieve with favorable shoes and > a fairly favorable carpet and favorable humidity. So, I think 10 KV is > common but much more is not. > > However, I remember experiencing one apartment with one exceptionally > favorable carpet and I somewhat remember making 15 mm, possibly 18 mm > sparks (corresponding to probably about 17 to possibly 20 KV). > The worst place I ever encountered was an electronics lab at university. They had these plastic chairs and in winter just standing up from one would generate 1cm sparks. They were quite painful as well, and no doubt absolutely fatal to anything more sensitive than a vacuum tube. -- Dirk http://www.transcendence.me.uk/ - Transcendence UK http://www.blogtalkradio.com/onetribe - Occult Talk Show
From: Archimedes' Lever on 1 Jun 2010 22:52
On Tue, 01 Jun 2010 11:31:56 +0100, Dirk Bruere at NeoPax <dirk.bruere(a)gmail.com> wrote: >Also, given the hypothesized rapid rise time, doesn't most of the >current flow on the surface ie skin - a literal "skin effect"? > No. Path of least resistance is the blood. Wires have 'skin effect'. Body limbs do not. Just ask the lady newscaster that had her arm literally burned off by the current flow she experienced. |