Difference between revisions of "Contact Physics – Formulas"
(→6.4.2 Contact Physics – Formulas) |
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===6.4.2 Contact Physics – Formulas=== | ===6.4.2 Contact Physics – Formulas=== | ||
| − | *'''Constriction resistance''' <br />R<sub>e</sub> = | + | *'''Constriction resistance''' <br />R<sub>e</sub> = \rho/2a |
(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) | ||
| − | R<sub>e</sub> = | + | R<sub>e</sub> = \rho/2Na |
(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) | ||
| − | R<sub>e</sub> = | + | 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 |
(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''' <br />R<sub>K</sub> = R<sub>e</sub> + R<sub>f</sub> | *'''Contact resistance''' <br />R<sub>K</sub> = R<sub>e</sub> + R<sub>f</sub> | ||
Revision as of 18:08, 26 March 2014
6.4.2 Contact Physics – Formulas
- Constriction resistance
Re = \rho/2a
(Single spot contact according to Holm; circular touching spot between clean contact surfaces) Re = \rho/2Na (Multi-spot contact according to Holm without influence between the N individual spots) Re = \rho/2 x \sum ai + 3 \pi \rho/32N² x \sum \sum (sij) i \neq j (Multi-spot contact according to Greenwood considering the influence between the spots)
- Contact resistance
RK = Re + Rf
- Path resistance
Rd = Rb + RK
- Contact resistance and contact force
RK = 280D ³ E(F · r) K
(According to Holm model for film-free spherical contact surfaces with plastic deformation of the contact material; Fk < 1 N for typical contact materials) RK = 9000 D H/ FK (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)
FA 0,8 x I2(Rule of thumb with FA in N and I in kA)
- Contact voltage and max. contact temperature
Tkmax 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
