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# Grounding

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 nkjordan23 (Automotive) 26 Jun 12 23:13
 Hello all, I am looking for some information to help me determine the amount of contact area and pressure needed to maintain a low grounding resistance between two pieces of stainless steel that are pressed together. During temp changes, things are shrinking and expanding cause fluctuations in ground resistance between the two metals. The only reference I have found is the one below that discusses pressure (force) in minor detail. Is there any other information out there that could help me calculate these two mechanical factors? Thanks! http://www.deringerney.com/capabilities/ContactSel...
 7anoter4 (Electrical) 28 Jun 12 9:35
 There is a lot of book regarding electrical contacts.Here are a few titles: http://books.google.com/books?id=DjnVY_UNhuQC&...
 7anoter4 (Electrical) 5 Jul 12 5:33
 According to Holm[ Electrical Contact Handbook-1958 Ragnar Holm] R=k/Fk^m R[ohm];Fk[kgf] k=7.6/10^3 ohm/kgf m=0.8 for steel-steel bar contact. The resistance depends upon clean state of the surfaces. Tk-Tn=I^2*ro*pi()*sigma/32/lambda/Fk Tk=contact temperature;Tn bar temperature far from contact point Tk=Uk^2/8/lambda/ro Uk=voltage drop contact across[V]. I[A];ro[elec.res.-ohm.cm];sigma=maximum material withstand pressure effort [kg/cm^2] lambda=thermal conductivity[w/cm.oC] Stainless steel electrical and thermal properties CINDAS REPORT 75/77 By C.Y.Ho & T.K.Cho http://www.google.co.il/url?sa=t&rct=j&q=s... 1 ohm.m=100 ohm.cm 1 w/m/oK=0.01 w/cm/oC

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