Difference between revisions of "Contact Physics – Formulas"
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*'''Dynamic contact separation''' (without considering magnetic fields caused by the current path) | *'''Dynamic contact separation''' (without considering magnetic fields caused by the current path) | ||
| − | : <math>F_A 0,8 | + | : <math>F_A \approx 0,8 xl^2</math> |
| − | (Rule of thumb with F<sub>A</sub> in N and | + | (Rule of thumb with F<sub>A</sub> in N and l in kA) |
*'''Contact voltage and max. contact temperature''' | *'''Contact voltage and max. contact temperature''' | ||
| − | : | + | : <math>T_kmax \approx 3200 U_K</math> |
| − | *'''Contact resistance at higher contact forces (according to Babikow)''' < | + | *'''Contact resistance at higher contact forces (according to Babikow)''' |
| − | For F<sub>K</sub> between 10 and 200 N | + | : <math>R_K = cF_k^{-m}</math> |
| − | c = material dependent proportionality factor | + | For F<sub>K</sub> between 10 and 200 N<br/> |
| + | c = material dependent proportionality factor<br/> | ||
m = shape dependent exponent of the contact force | m = shape dependent exponent of the contact force | ||
==References== | ==References== | ||
[[Application Tables and Guideline Data for Use of Electrical Contact Design#References|References]] | [[Application Tables and Guideline Data for Use of Electrical Contact Design#References|References]] | ||
Revision as of 11:03, 31 March 2014
6.4.2 Contact Physics – Formulas
- Constriction resistance
(Single spot contact according to Holm; circular touching spot between clean contact surfaces)
(Multi-spot contact according to Holm without influence between the N individual spots)
(Multi-spot contact according to Greenwood considering the influence between the spots)
- Contact resistance
- Path resistance
- Contact resistance and contact force
![R_K = 280\rho \sqrt[3]{E (F_K \cdot r)}](/matheasy/bda0b56c91fccaa4c9a75816e15c1815.svg)
(According to Holm model for film-free spherical contact surfaces with plastic deformation of the contact material; Fk < 1 N for typical contact materials)
(According to Holm model for film-free spherical contact surfaces with plastic deformation of the contact material; Fk > 5 N for typical contact materials)
- Dynamic contact separation (without considering magnetic fields caused by the current path)
(Rule of thumb with FA in N and l in kA)
- Contact voltage and max. contact temperature
- Contact resistance at higher contact forces (according to Babikow)
For FK between 10 and 200 N
c = material dependent proportionality factor
m = shape dependent exponent of the contact force
