===6.4.2 Contact Physics – Formulas==={| |'''Editor''':|DODUCO Holding GmbH<br> Im Altgefäll 12<br>
*'''Constriction resistance''' <math>R_e = \rho/2a</math>(Single spot contact according to Holm; circular touching spot between cleancontact surfaces)<math>R_e = \rho/2Na</math>(Multi-spot contact according to Holm without influence between the Nindividual spots)<math>R_e = \rho/2 x \sum a_i + 3 \pi \rho75181 Pforzheim /32N² x \sum \sum (s_ij) i \neq jGermany</mathbr>(Multi-spot contact according to Greenwood considering the influence betweenthe spots)
*'''Contact resistance''' R<sub>K</sub> = R<sub>e</sub> Phone + R<sub>f49 (0) 7231 602-0</subbr>
*'''Path resistance''' cR<sub>d</sub> = R<sub>b</sub> Fax + R<sub>K49 (0) 7231 602-398</subbr>
*'''Contact resistance and contact force''' <math>R_K = 280D ³ E(F · r) K</math> (According to Holm model for film-free spherical contact surfaces with plasticdeformation of the contact material; F<sub>k</sub> < 1 N for typical contact materials)<math>R_K = 9000 D H/ FK</math>(According to Holm model for film-free spherical contact surfaces with plasticdeformation of the contact material; F<sub>k</sub> > 5 N for typical contact materials) *'''Dynamic contact separation''' (without considering magnetic fields caused by the current path) <br />F<sub>A</sub> 0,8 x I<sup>2</sup>(Rule of thumb with F<sub>A</sub> in N and I in kA) *'''Contact voltage and maxMail: info@doduco. contact temperature''' <br />T<sub>kmax</sub> 3200 U<sub>K</sub> *'''Contact resistance at higher contact forces (according to Babikow)''' net<br />R<sub>K</sub> = cF -m KFor F<sub>K</sub> between 10 and 200 Nc = material dependent proportionality factorm = shape dependent exponent of the contact force ==References==[[Application Tables and Guideline Data for Use of Electrical Contact Design#References|References]]
