Difference between revisions of "Contact Physics – Formulas"

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===6.4.2 Contact Physics – Formulas===
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{|
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|'''Editor''':
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|DODUCO Holding GmbH<br>
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Im Altgefäll 12<br>
  
*'''Constriction resistance''' <math>R_e = \rho/2a</math>
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75181 Pforzheim / Germany<br>
(Single spot contact according to Holm; circular touching spot between clean
 
contact surfaces)
 
<math>R_e = \rho/2Na</math>
 
(Multi-spot contact according to Holm without influence between the N
 
individual spots)
 
<math>R<sub>e</sub> = \rho/2 x \sum a<sub>i</sub> + 3 \pi \rho/32N² x \sum \sum (s<sub>ij</sub>) i \neq j</math>
 
(Multi-spot contact according to Greenwood considering the influence between
 
the spots)
 
  
*'''Contact resistance''' <br />R<sub>K</sub> = R<sub>e</sub> + R<sub>f</sub>
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Phone +49 (0) 7231 602-0<br>
  
*'''Path resistance''' <br />R<sub>d</sub> = R<sub>b</sub> + R<sub>K</sub>
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Fax +49 (0) 7231 602-398<br>
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*'''Contact resistance and contact force''' <math><br />R<sub>K</sub> = 280D ³ E(F · r) K</math>
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Mail: info@doduco.net<br>
(According to Holm model for film-free spherical contact surfaces with plastic
 
deformation of the contact material; F<sub>k</sub> < 1 N for typical contact materials)
 
<math>R<sub>K</sub> = 9000 D H/ FK</math>
 
(According to Holm model for film-free spherical contact surfaces with plastic
 
deformation 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 max. contact temperature''' <br />T<sub>kmax</sub> 3200 U<sub>K</sub>
 
 
 
*'''Contact resistance at higher contact forces (according to Babikow)''' <br />R<sub>K</sub> = cF -m K
 
For F<sub>K</sub> between 10 and 200 N
 
c = material dependent proportionality factor
 
m = shape dependent exponent of the contact force
 
 
 
==References==
 
[[Application Tables and Guideline Data for Use of Electrical Contact Design#References|References]]
 

Latest revision as of 11:37, 7 February 2019

Editor: DODUCO Holding GmbH

Im Altgefäll 12

75181 Pforzheim / Germany

Phone +49 (0) 7231 602-0

Fax +49 (0) 7231 602-398


Mail: info@doduco.net