I had written a paper, “Human Body Impedance Model at Radio Frequencies” for the 2016 IEEE Symposium for Product Compliance Engineering. This paper is on IEEE Xplore.
Abstract— This paper examines the frequency response of human body-simulating impedance networks found in information and communication technology safety standards, then explores their reactions at radio frequencies used for wireless telephony. It explores the possible existence of human-body inductance, resonance and skin effect. Finally, it postulates a working model for evaluating the safety of high-power circuits operating at radio frequencies. Don Gies <mailto:[email protected]> [email protected] Mobile: 1.732.207.7828 From: Pete Perkins <[email protected]> Sent: Thursday, March 14, 2019 11:53 AM To: [email protected] Subject: Re: [PSES] human skin resistance The standard body models used in the safety standards to provide electric shock protection provide for a ‘ combo in-and out RC skin impedance’ and a ‘body resistance’. The modeled circuit used in 60990 for large area of contact is skin impedance of 1500 ohms and 0.22uf and the internal body resistance ‘bag of saltwater’ of 500 ohms; this has been the traditional European body circuit, in NA UL has used slightly different values; there is only a small difference in measured touch current between these circuits. The large area of contact is considered the worst case. The component values in the model vary with contact area – as the contact area gets smaller the skin impedance resistance get higher and the capacitance changes because of the smaller area. There are several other more complex body models in the literature which seek to auto compensate for some of the variables encountered in electric shock work. Altho they seem to provide some of advantages claimed they have not come into general use. :>) br, Pete Peter E Perkins, PE Principal Product Safety & Regulatory Affairs Consultant PO Box 23427 Tigard, ORe 97281-3427 503/452-1201 IEEE Life Fellow [email protected] <mailto:[email protected]> Entropy ain’t what it used to be From: Richard Nute <[email protected] <mailto:[email protected]> > Sent: Wednesday, March 13, 2019 12:07 PM To: [email protected] <mailto:[email protected]> Subject: [PSES] human skin resistance John referenced “skin resistance.” To my knowledge, there is no research that shows skin resistance and body resistance as separate parameters. We only know total body resistance, and that it is a variable that changes – lowers -- with applied voltage and time. Having said that, a good guess that skin resistance is the predominant parameter at low voltages. The “body” is comprised of water-predominate organs, so is likely to be a lower resistance than skin resistance and relatively constant with voltage. We also know that capacitance parallels the total body resistance. But, as with resistance, we don’t know how to apportion the capacitance to the skin and to the body. If you know of any such research, please let me know. Best regards, Rich From: John Woodgate <[email protected] <mailto:[email protected]> > Sent: Wednesday, March 13, 2019 1:30 AM To: [email protected] <mailto:[email protected]> Subject: Re: [PSES] classification of the output We found very great differences in human 'skin resistance' at effectively zero voltage when designing TV tuners with touch-contact channel selection. We had to make the sensitivity so high that there was a risk that houseflies would change the channel. Best wishes John Woodgate OOO-Own Opinions Only J M Woodgate and Associates www.woodjohn.uk <http://www.woodjohn.uk> Rayleigh, Essex UK On 2019-03-13 05:22, Pete Perkins wrote: - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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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) 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]>
