Difference between revisions of "Contact Physics – Formulas"
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===6.4.2 Contact Physics – Formulas=== | ===6.4.2 Contact Physics – Formulas=== | ||
| − | *'''Constriction resistance''' <math>R_e = \rho/2a</math> | + | *'''Constriction resistance''' |
| + | : <math>R_e = \rho/2a</math> | ||
(Single spot contact according to Holm; circular touching spot between clean | (Single spot contact according to Holm; circular touching spot between clean | ||
contact surfaces) | contact surfaces) | ||
| − | <math>R_e = \rho/2Na</math> | + | : <math>R_e = \rho/2Na</math> |
(Multi-spot contact according to Holm without influence between the N | (Multi-spot contact according to Holm without influence between the N | ||
individual spots) | individual spots) | ||
| − | <math>R_e = \rho/2 x \sum a_i + 3 \pi \rho /32N^2 x \sum \sum (s_ij) i \neq j</math> | + | : <math>R_e = \rho/2 x \sum a_i + 3 \pi \rho /32N^2 x \sum \sum (s_ij) i \neq j</math> |
(Multi-spot contact according to Greenwood considering the influence between | (Multi-spot contact according to Greenwood considering the influence between | ||
the spots) | the spots) | ||
| − | *'''Contact resistance''' | + | *'''Contact resistance''' |
| + | : <math>R_K = R_e + R_f</math> | ||
| − | *'''Path resistance''' | + | *'''Path resistance''' |
| + | : <math>cR_d = R_b + R_K</math> | ||
| − | *'''Contact resistance and contact force''' <math>R_K = 280\rho \sqrt[3]{E (F_K \cdot r)} </math> | + | *'''Contact resistance and contact force''' |
| + | : <math>R_K = 280\rho \sqrt[3]{E (F_K \cdot r)} </math> | ||
(According to Holm model for film-free spherical contact surfaces with plastic | (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) | deformation of the contact material; F<sub>k</sub> < 1 N for typical contact materials) | ||
| − | <math>R_K = 9000 D H/ FK</math> | + | : <math>R_K = 9000 D H/ FK</math> |
(According to Holm model for film-free spherical contact surfaces with plastic | (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) | 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) < | + | *'''Dynamic contact separation''' (without considering magnetic fields caused by the current path) |
| + | : <math>F_A 0,8 /cdot I_2</math> | ||
| + | (Rule of thumb with F<sub>A</sub> in N and I in kA) | ||
| − | *'''Contact voltage and max. contact temperature''' | + | *'''Contact voltage and max. contact temperature''' |
| + | : T_k max</sub> 3200 U<sub>K</sub> | ||
*'''Contact resistance at higher contact forces (according to Babikow)''' <br />R<sub>K</sub> = cF -m K | *'''Contact resistance at higher contact forces (according to Babikow)''' <br />R<sub>K</sub> = cF -m K | ||
Revision as of 10:55, 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 I in kA)
- Contact voltage and max. contact temperature
- T_k max 3200 UK
- Contact resistance at higher contact forces (according to Babikow)
RK = cF -m K
For FK between 10 and 200 N c = material dependent proportionality factor m = shape dependent exponent of the contact force
